EXHIBIT 4.2

THESE  SECURITIES HAVE NOT BEEN REGISTERED  UNDER THE SECURITIES ACT OF 1933, AS
AMENDED,  OR THE SECURITIES  LAWS OF ANY STATE AND CANNOT BE SOLD OR TRANSFERRED
UNLESS AND UNTIL THEY ARE SO REGISTERED OR UNLESS AN EXEMPTION UNDER SUCH ACT OR
LAWS IS AVAILABLE. THE TRANSFERABILITY OF THESE SECURITIES IS FURTHER SUBJECT TO
THE  PROVISIONS OF A UNIT PURCHASE  AGREEMENT  DATED AS OF MARCH 7,  1996 BY AND
BETWEEN THE COMPANY AND CERBERUS PARTNERS, L.P.


                  AMENDED AND RESTATED CLASS B 13% CONVERTIBLE
               SENIOR SUBORDINATED PAY-IN-KIND DEBENTURE DUE 1999

                                  July 29, 1997


     LOGIMETRICS,  INC., a Delaware corporation (the "Company"), hereby promises
to pay to the order of Cerberus  Partners,  L.P.  (together with its, his or her
successors and assigns,  the "Holder") the principal  amount of One Million Five
Hundred  Thousand  Dollars  ($1,500,000)  in lawful money of the United  States,
together with interest  thereon  calculated  from the date hereof and payable in
accordance with the provisions of this debenture ("Debenture").

     By accepting this Debenture,  the Holder agrees that the obligations of the
Company to the Holder under this  Debenture  shall be  subordinated  only to the
Senior  Debt (as  hereinafter  defined) of the  Company,  all upon the terms set
forth in paragraph 4 hereof.

     This  Debenture may be  surrendered  for transfer or exchange by the Holder
hereof upon surrender of this Debenture, together with a properly completed bond
power or other instrument of transfer, and any required signature guarantees, at
the office of the Company set forth in Section 11 hereof. Upon proper surrender,
the  Company  shall  issue  one or more  replacement  Debentures  of like  tenor
registered in the names and in the  denominations  requested by the surrendering
Holder  and dated the date of  issuance  thereof;  provided,  however,  that (i)
appropriate adjustments shall be made to reflect the date of issue and principal
amount of each such replacement  Debenture,  (ii) the aggregate principal amount
of all Debentures,  excluding  Accrued  Interest  Debentures (as defined below),
shall be  limited to  $1,500,000,  and (iii) no  Debenture  shall be issued in a
principal  amount of less than  $50,000  unless in  connection  with a  transfer
resulting  from  the  complete  liquidation  of  the  original  Holder  of  this
Debenture. All Debentures shall rank pari passu.

     1.  Payment of Interest.  Subject to  subparagraph  6(c)(xviii)(C)  hereof,
interest will accrue from the date hereof at the rate of thirteen  percent (13%)
per annum on the unpaid 

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principal amount of this Debenture outstanding from time to time on the basis of
a 360-day year for the actual  number of days  elapsed.  Subject to  paragraph 4
hereof,  the Company  will pay to the Holder all accrued and unpaid  interest on
this Debenture on October 15, 1997 and quarterly thereafter,  in arrears, on the
15th day of  January,  the 15th day of April,  the 15th day of July and the 15th
day of October (each,  an "Interest  Payment Date") to and including the earlier
to  occur  of  the  Conversion  Date  (hereinafter  defined)  or  the  Due  Date
(hereinafter  defined).  Interest will accrue at the greater of the Default Rate
(hereinafter  defined)  and the rate of fifteen  percent  (15%) per annum on any
principal  payment past due under this Debenture and,  unless  prohibited  under
applicable law (and if so prohibited then only to the extent not so prohibited),
on any  interest  which  has not  been  paid on the  date on which it is due and
payable  (without  giving effect to any applicable  grace periods or paragraph 4
hereof) until such time as payment therefor is actually delivered to the Holder.

     On each Interest  Payment Date other than the Due Date (as defined  below),
in payment of the interest due on this Debenture on such Interest  Payment Date,
the Company  shall  deliver to the Holder of this  Debenture a new Debenture (an
"Accrued  Interest  Debenture"),  in the  form of  this  Debenture,  dated  such
Interest Payment Date (and bearing interest from such Interest Payment Date) and
having a principal amount corresponding to the interest due on this Debenture on
such  Interest  Payment Date. On the Due Date, in payment of the interest due on
this  Debenture on such date,  the Company shall  deliver,  at the option of the
Holder, either (a) a cash payment in such amount, or (b) the number of shares of
Common  Stock,  par value $.01 per share  ("Common  Stock"),  into which Accrued
Interest Debentures would be convertible pursuant to Section 6 hereof if Accrued
Interest  Debentures had been issued to the Holder on the Due Date in payment of
such interest and such Accrued Interest  Debentures were converted by the Holder
immediately  thereafter.  Unless the Holder  gives the  Company not less than 10
days' prior written  notice of the exercise of such option,  the Holder shall be
deemed to have  irrevocably  elected to receive payment of such interest in cash
on the Due Date. Any exercise or deemed exercise of such option shall be binding
on any subsequent Holder of this Debenture.

     2.    Payment of Principal on Debenture.

          (a) Scheduled Payments. The Company will repay the principal amount of
this Debenture on July 29, 1999 ("Due Date").

          (b) Optional  Prepayment.  At any time after April 29, 1998,  provided
that the Registration Statement (hereinafter defined) is effective and available
for  sales of  Registrable  Securities  (hereinafter  defined)  thereunder,  the
Company may at any time hereafter prepay,  without premium or penalty,  all (but
not  less  than  all) of the  outstanding  principal  amount  of the  Debentures
(including,  for this purpose, the Accrued Interest  Debentures),  together with
interest accrued on such prepaid amount to the date of payment; provided (i) the
average  closing  price of the  Company's  Common Stock on days the Common Stock
traded during the 120-day  period  

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immediately  preceding  the date of the notice  provided  for in  paragraph  (c)
hereinbelow  shall have been not less than $5.00,  and (ii) the closing price of
the Common Stock for each of the 30 trading days immediately  preceding the date
of such notice  shall have been not less than  $5.00,  adjusted in each case for
stock splits, stock dividends or other similar transactions  affecting the price
of the Common Stock.  All such  prepayments  shall be applied pro rata to all of
the  Debentures.  At the option of the Holder,  interest  accrued on the prepaid
amount to the date of  payment  shall be paid  either  (a) in cash or (b) by the
issuance  by the  Company  to the  Holder of shares of Common  Stock  into which
Accrued Interest Debentures would be convertible pursuant to Section 6 hereof if
Accrued  Interest  Debentures  had been  issued  to the  Holder  on such date in
payment of such interest and such Accrued Interest  Debentures were converted by
the Holder immediately thereafter.  Unless the Holder gives the Company not less
than 10 days' prior  written  notice of the exercise of such option,  the Holder
shall be deemed to have irrevocably  elected to receive payment of such interest
in cash. Any exercise or deemed  exercise of such option shall be binding on any
subsequent Holder of this Debenture.

          (c) Notice of Prepayment.  The Company will give written notice of its
election to prepay this  Debenture to the Holder in person or by  registered  or
certified mail, return receipt requested, at least thirty (30) and not more than
forty-five (45) days prior to the date of prepayment.  On the date of prepayment
specified  in the  Company's  notice,  the Company will deliver to the Holder of
this  Debenture in person or by registered  or certified  mail,  return  receipt
requested,  a cashier's or certified check for the entire outstanding  principal
amount being prepaid,  together with all accrued  interest  thereon  through the
date of prepayment.

     3. Intentionally Omitted.

     4. Subordination.  The Company's payment, whether voluntary or involuntary,
whether in cash, property, securities or otherwise and whether by application of
offset or otherwise (hereinafter "Payment") of any of its obligations under this
Debenture,  other than the  issuance of Accrued  Interest  Debentures,  shall be
subject to the following restrictions:

          (a)  Subordination  to Senior Debt.  Anything in this Debenture to the
contrary  notwithstanding,  the  obligations  of the  Company  in respect of the
principal of and interest  (including  any premium or penalty) on this Debenture
and any other amounts due under this Debenture (the  "Subordinated  Debt") shall
be subordinate  and junior in right of payment,  to the extent and in the manner
hereinafter set forth, to the Senior Debt. "Senior Debt", when used with respect
to the Company, means (i) the Company's indebtedness to North Fork Bank ("Bank")
under (A) that certain  $640,000.04  Restated and Amended Term Loan Note,  dated
April 25,  1997,  and (B) that  certain  $2,200,000  Sixth  Restated and Amended
Revolving  Credit  Note,  dated  April 25,  1997,  in each case,  together  with
interest  thereon  and  (ii)  renewals,  extensions,  refinancings,   deferrals,
restructurings,  amendments,  modifications  and  waivers  of  the  indebtedness
described in clause (i) above.

<PAGE>

          (b)  Default on Senior  Debt.  So long as the Senior Debt has not been
paid in full,  if there  shall  occur a default in the  payment  when due of any
amount  due and owing on account of Senior  Debt (any of the  foregoing  being a
"Senior  Debt  Default")  then,  from and after the  receipt of  written  notice
thereof from the holder of Senior Debt unless and until such Senior Debt Default
shall have been  remedied or waived the Company will not make any Payment on any
Subordinated  Debt,  and the  Holders of  Subordinated  Debt will not receive or
accept any direct or indirect  Payment in respect  thereof,  and the Company may
not redeem or otherwise acquire any Subordinated Debt.

          (c) Changes in Senior Debt. Any holder of Senior Debt may, at any time
and from time to time,  without  the  consent  of, or notice  to, the Holder and
without  incurring  responsibility  to the  Holder,  and  without  impairing  or
releasing the obligations of the Holder hereunder:

               (i)  Change  the  manner,  place or terms of payment or change or
     extend  the time of  payment  of or renew or alter the  Senior  Debt or any
     portion thereof; provided, however, that without the written consent of the
     Majority Holders (hereinafter defined) the principal amount of and interest
     rate  applicable  from  time to time to  Senior  Debt may not be  increased
     (other than  pursuant to the terms of the Senior Debt as such terms existed
     on the date of issuance hereof);

               (ii)  Sell,   exchange,   release  or  otherwise  deal  with  any
     collateral  securing the Senior Debt or any other property by whomsoever at
     any time pledged or mortgaged to secure,  or however  securing,  the Senior
     Debt or any portion thereof; and

               (iii) Apply any sums by  whomsoever  paid or however  released to
     the Senior Debt or any portion thereof.

          (d) Consent to Senior  Debt.  By  acceptance  of this  Debenture,  the
Holder hereby consents to the making of Senior Debt and hereby acknowledges that
each current and future holder of Senior Debt has relied, and in the future will
rely, upon the terms of this Debenture. The holders of Senior Debt shall have no
liability to the Holder and the Holder hereby waives any claim which it may have
now or  hereafter  against  any holder of Senior Debt  arising  from any and all
actions  which any holder of Senior  Debt may take or omit to take in good faith
with regard to the Senior Debt or its rights or obligations hereunder.

          (e) Payments in Trust.  Until the Senior Debt has been repaid in full,
in the event the  Holder  shall  receive  any  Payment in  contravention  of the
provisions  of  this   paragraph 4   including,   Payments   arising  under  the
subordination  provisions of any other  indebtedness of the Company,  the Holder
shall hold all such Payments so received in trust for the holders of Senior

<PAGE>

Debt and shall  forthwith  turn over all such  Payments to the holders of Senior
Debt in the form  received  (except for the  endorsement  or  assignment  of the
Holder as necessary,  without  recourse or warranty) to be applied to payment of
the Senior Debt whether or not then due and payable.  Any Payment so received in
trust  and  turned  over to the  holders  of Senior  Debt  shall not be deemed a
Payment in satisfaction of the Subordinated Debt by the Company.

          (f)  Payment in full of Senior  Debt;  Subrogation.  If any Payment to
which a Holder of  Subordinated  Debt would otherwise have been entitled but for
the  provisions of this  paragraph 4  shall have been  applied,  pursuant to the
provisions of this paragraph 4,  to the payment of Senior Debt, then and in such
case, the Holder of the Subordinated  Debt (i) shall be entitled to receive from
the holders of Senior Debt at the time outstanding any payments or distributions
received by such  holders of Senior Debt in excess of the amount  sufficient  to
pay all  Senior  Debt  in cash in full  (whether  or not  then  due),  and  (ii)
following  payment of the Senior Debt in full,  shall be subrogated to any right
of the  holders  of Senior  Debt to  receive  any and all  further  payments  or
distributions  applicable to Senior Debt, until all the Subordinated  Debt shall
have been paid in full. If the Holder of the  Subordinated  Debt shall have been
subrogated  to the rights of the holders of Senior Debt due to the  operation of
this  paragraph 4(f),  the Company agrees to take all such reasonable actions as
are  requested by such Holders of the  Subordinated  Debt in order to cause such
Holders to be able to obtain  payments  from the  Company  with  respect to such
subrogation rights as soon as possible.

          (g) No Impairment of the Company's  Obligations.  Nothing contained in
this paragraph 4, as between the Company and the Holder of this Debenture, shall
impair the obligation of the Company,  which is absolute and  unconditional,  to
pay to the Holder the  principal of and  interest on this  Debenture as and when
the same shall become due and payable in accordance with the terms hereof.

          (h)  Advances  in  Reliance.  The  Holder  of this  Debenture,  by its
acceptance hereof,  agrees that each holder of Senior Debt has advanced funds or
may in the  future  advance  funds in  reliance  upon the terms  and  conditions
hereof.

          (i)  Non-Waiver  of Rights.  No right of any holder of Senior  Debt to
enforce its right of  subordination  as herein provided shall at any time in any
way be  prejudiced  or  impaired by any act or failure to act on the part of the
Company,  or by  any  act or  failure  to act  by  any  such  holder,  or by any
non-compliance  by the Company with the terms,  provisions and covenants of this
Debenture,  regardless of any  knowledge  thereof any such holder may have or be
otherwise charged with.

          (j) Recaptured  Payments.  Any Payments received by a holder of Senior
Debt from the Company or the Holder  which,  in  connection  with an  Insolvency
Event or  Proceeding  

<PAGE>

(hereinafter  defined),  is required to be remitted to the payor or the bankrupt
estate  shall  not be  deemed a Payment  to such  holder of Senior  Debt for all
purposes hereunder.

    5.  Security. The obligations of the Company to the Holder of this Debenture
(including the obligation to pay the Accrued  Interest  Debentures when due) are
secured by certain Collateral to the extent provided in the Amended and Restated
Security  Agreement,  dated as of March 7, 1996,  as amended and  restated as of
July 29, 1997 ("Security Agreement"), made by the Company in favor of Holders of
the Debentures.  In addition to all rights and remedies provided herein, Holders
of  the  Debentures  are  entitled  to the  benefits  provided  in the  Security
Agreement. By accepting this Debenture,  the Holder hereof agrees to be bound by
the terms of the Security Agreement.

     6.   Conversion Rights.

          (a) The  Holder  of this  Debenture  has the  right  (the  "Conversion
Right"),  exercisable  at his,  her or its option at any time  during  which the
principal  amount of this Debenture is  outstanding,  to convert this Debenture,
but only in whole,  into Two  Million  Five  Hundred  Forty-Two  Thousand  Three
Hundred  Eighty  (2,542,380)  shares of Common  Stock,  subject to adjustment in
certain circumstances as provided herein.

          (b)  The  Conversion  Right  is  exercisable  upon  surrender  of this
Debenture,  together with a conversion  notice,  in the form attached  hereto as
Exhibit A, duly executed and completed, evidencing the election of the Holder to
exercise the Conversion  Right, at the Company's  principal office at 50 Orville
Drive,  Bohemia,  New York 11716.  The registered  owner of this Debenture shall
become the record holder of the shares of Common Stock issuable upon  conversion
as of the date of exercise of the Conversion Right (the "Conversion  Date"). The
shares  issued in  connection  with the  Conversion  Right  shall be  registered
initially in the name of the Holder,  and  delivered to the Holder no later than
two (2) business days after receipt of a properly  completed  conversion notice.
Upon conversion, the Company shall pay to the Holder accrued but unpaid interest
on this Debenture up to, but excluding,  the Conversion  Date.. At the option of
the Holder, such accrued but unpaid interest shall be paid either (a) in cash or
(b) by the  issuance by the Company to the Holder of shares of Common Stock into
which Accrued  Interest  Debentures  would be convertible  pursuant to Section 6
hereof if Accrued Interest Debentures had been issued to the Holder on such date
in payment of such interest and such Accrued Interest  Debentures were converted
by the Holder  immediately  thereafter.  Unless the Holder gives the Company not
less than 10 days' prior  written  notice of the  exercise of such  option,  the
Holder shall be deemed to have  irrevocably  elected to receive  payment of such
interest  in cash.  Any  exercise or deemed  exercise  of such  option  shall be
binding on any subsequent Holder of this Debenture.

<PAGE>

          (c) In  case,  at any  time or from  time to time  after  the  date of
issuance of this Debenture  ("Issuance  Date"),  the Company shall issue or sell
shares of its Common  Stock  (other  than any  Common  Stock  issuable  upon the
exercise or conversion of (i) the Debentures (and any  replacement  Debenture or
Debentures issued upon transfer or exchange of this Debenture), (ii) any Accrued
Interest  Debentures (and any replacement  Accrued Interest Debenture or Accrued
Interest  Debentures  issued upon  transfer or exchange of the Accrued  Interest
Debentures),  (iii) the Company's  Class A 13% Convertible  Senior  Subordinated
Pay-in-Kind  Debentures due 1999 (the "Class A Debentures") (and any replacement
Class A Debenture or Class A Debentures  issued upon transfer or exchange of the
Class A  Debentures),  (iv) any  additional  securities  issued  in lieu of cash
interest  otherwise  payable  on the Class A  Debentures  (the  "Class A Accrued
Interest Debentures") (and any replacement Class A Accrued Interest Debenture or
Class A Accrued  Interest  Debentures  issued  upon  transfer or exchange of the
Class A Accrued  Interest  Debentures),  (v) securities  outstanding on the date
hereof,  (vi) awards made pursuant to the Company's Stock  Compensation  Program
(the "Plan"),  (vii) awards made pursuant to any incentive  compensation plan or
arrangement  approved by the Company's Board of Directors or by the Compensation
Committee of the  Company's  Board of Directors,  (viii) the Company's  Series G
Warrants,  (ix) the Company's  Series H Warrants,  or (x) the Company's Series I
Warrants)  (such  securities,  collectively,  the  "Subject  Securities")  for a
consideration per share less than $.52 per share ("Trigger Price"), or, if a Pro
Forma  Adjusted  Trigger  Price  (hereinafter  defined)  shall be in  effect  as
provided  below in this  paragraph (c),  then less than such Pro Forma  Adjusted
Trigger  Price  per  share,  then  and in each  such  case  the  Holder  of this
Debenture, upon the conversion hereof as provided in paragraph (a) hereof, shall
be  entitled  to  receive,  in lieu of the  shares of Common  Stock  theretofore
receivable upon the conversion of this  Debenture,  a number of shares of Common
Stock  determined  by (a)  dividing  the Trigger  Price by a Pro Forma  Adjusted
Trigger Price per share to be computed as provided below in this  paragraph (c),
and (b)  multiplying  the  resulting  quotient by the number of shares of Common
Stock  into which  this  Debenture  is then  convertible.  A Pro Forma  Adjusted
Trigger  Price per share shall be the price  computed  (to the nearest  cent,  a
fraction of half cent or more being considered a full cent):

          by dividing (i) the sum of (x) the result  obtained by multiplying the
          number  of  shares  of  Common   Stock  of  the  Company   outstanding
          immediately prior to such issue or sale by the Trigger Price (or, if a
          Pro Forma Adjusted  Trigger Price shall be in effect,  by such Price),
          and (y) the  consideration,  if any, received by the Company upon such
          issue or sale,  by (ii) the  number of  shares of Common  Stock of the
          Company outstanding immediately after such issue or sale.

For the purpose of this paragraph (c):

               (i) In case the Company  splits its Common Stock or shall declare
     any dividend, or make any other distribution, upon any stock of the Company
     of any class 

<PAGE>

     payable in Common Stock,  or in any stock or other  securities  directly or
     indirectly  convertible  into or  exchangeable  for Common  Stock (any such
     stock  or  other   securities   being   hereinafter   called   "Convertible
     Securities"), such split, declaration or distribution shall be deemed to be
     an issue or sale (as of the record date for such  split,  dividend or other
     distribution),   without  consideration,  of  such  Common  Stock  or  such
     Convertible Securities, as the case may be.

               (ii) In case the  Company  shall  issue  or sell any  Convertible
     Securities other than the Subject Securities, there shall be determined the
     price per share for which Common Stock is issuable  upon the  conversion or
     exchange thereof,  such  determination to be made by dividing (a) the total
     amount received or receivable by the Company as consideration for the issue
     or sale of such Convertible  Securities,  plus the minimum aggregate amount
     of  additional  consideration,  if any,  payable  to the  Company  upon the
     conversion  or exchange  thereof,  by (b) the  maximum  number of shares of
     Common Stock of the Company issuable upon the conversion or exchange of all
     such Convertible Securities.

               If the  price  per  share so  determined  shall be less  than the
     Trigger  Price  (or,  if a Pro Forma  Adjusted  Trigger  Price  shall be in
     effect,  less than such  Price) as of the date of such issue or sale,  then
     such  issue or sale  shall be deemed to be an issue or sale for cash (as of
     the date of issue or sale of such  Convertible  Securities) of such maximum
     number  of shares  of  Common  Stock at the price per share so  determined,
     provided that, if such Convertible  Securities shall by their terms provide
     for an increase or  increases,  with the passage of time,  in the amount of
     additional consideration, if any, payable to the Company, or in the rate of
     exchange,  upon the conversion or exchange thereof,  the Pro Forma Adjusted
     Trigger Price per share shall,  forthwith  upon any such increase  becoming
     effective,  be readjusted to reflect the same, and provided,  further, that
     upon the  expiration  of such  rights of  conversion  or  exchange  of such
     Convertible Securities,  if any thereof shall not have been exercised,  the
     Pro Forma  Adjusted  Trigger Price per share shall  forthwith be readjusted
     and thereafter be the price which it would have been had an adjustment been
     made on the basis  that the only  shares of Common  Stock so issued or sold
     were  those  issued  or  sold  upon  the  conversion  or  exchange  of such
     Convertible  Securities,  and  that  they  were  issued  or  sold  for  the
     consideration  actually  received by the Company  upon such  conversion  or
     exchange, plus the consideration,  if any, actually received by the Company
     for the issue or sale of all such  Convertible  Securities which shall have
     been converted or exchanged.

               (iii) In case the  Company  shall  grant any rights or options to
     subscribe  for,  purchase or  otherwise  acquire  Common Stock of any class
     other than the Subject Securities,  there shall be determined the price per
     share for which Common  Stock is issuable  upon the exercise of such rights
     or options, such determination to be made by 

<PAGE>

     dividing  (a) the total  amount,  if any,  received  or  receivable  by the
     Company as consideration  for the granting of such rights or options,  plus
     the minimum aggregate amount of additional  consideration,  if any, payable
     to the Company  upon the  exercise  of such  rights or options,  by (b) the
     maximum number of shares of Common Stock issuable upon the exercise of such
     rights or options.

               If the  price  per  share so  determined  shall be less  than the
     Trigger  Price  (or,  if a Pro Forma  Adjusted  Trigger  Price  shall be in
     effect,  less than such  Price) as of the date of such issue or sale,  then
     the  granting of such  rights or options  shall be deemed to be an issue or
     sale for cash (as of the date of the granting of such rights or options) of
     such  maximum  number of  shares of Common  Stock at the price per share so
     determined,  provided  that, if such rights or options shall by their terms
     provide  for an  increase or  increases,  with the passage of time,  in the
     amount of additional consideration, if any, payable to the Company upon the
     exercise  thereof,  the Pro Forma  Adjusted  Trigger Price per share shall,
     forthwith  upon any such  increase  becoming  effective,  be  readjusted to
     reflect the same, and provided,  further,  that upon the expiration of such
     rights or options,  if any thereof shall not have been  exercised,  the Pro
     Forma  Adjusted  Trigger Price per share shall  forthwith be readjusted and
     thereafter  be the price  which it would have been had an  adjustment  been
     made on the basis  that the only  shares of Common  Stock so issued or sold
     were those  issued or sold upon the  exercise of such rights or options and
     that they were issued or sold for the  consideration  actually  received by
     the Company upon such exercise,  plus the  consideration,  if any, actually
     received  by the  Company  for the  granting of all such rights or options,
     whether or not exercised.

               (iv) In case the  Company  shall  grant any  rights or options to
     subscribe for, purchase or otherwise acquire  Convertible  Securities other
     than the Subject Securities,  such Convertible  Securities shall be deemed,
     for the purposes of  subparagraph (iii)  above, to have been issued or sold
     for the total amount received or receivable by the Company as consideration
     for the  granting  of such  rights or options  plus the  minimum  aggregate
     amount of additional consideration, if any, payable to the Company upon the
     exercise of such rights or options,  provided that,  upon the expiration of
     such rights or options,  if any thereof shall not have been exercised,  the
     Pro Forma  Adjusted  Trigger Price per share shall  forthwith be readjusted
     and thereafter be the price which it would have been had an adjustment been
     made upon the basis that the only Convertible  Securities so issued or sold
     were those  issued or sold upon the  exercise of such rights or options and
     that they were issued or sold for the  consideration  actually  received by
     the Company upon such exercise,  plus the  consideration,  if any, actually
     received  by the  Company  for the  granting of all such rights or options,
     whether or not exercised.

<PAGE>


               (v) In case any shares of stock or other  securities,  other than
     Common  Stock of the  Company,  shall at any  time be  receivable  upon the
     conversion of this  Debenture,  and in case any  additional  shares of such
     stock or any additional such  securities (or any stock or other  securities
     convertible into or exchangeable for any such stock or securities) shall be
     issued or sold for a consideration per share such as to dilute the purchase
     rights  evidenced  by this  Debenture,  then and in each  such case the Pro
     Forma  Adjusted  Trigger  Price  per share  shall  forthwith  be  adjusted,
     substantially in the manner provided for above in this paragraph (c), so as
     to  protect  the  Holder  of this  Debenture  against  the  effect  of such
     dilution.

               (vi) In case any shares of Common Stock or Convertible Securities
     or any rights or options to subscribe  for,  purchase or otherwise  acquire
     any  Common  Stock or  Convertible  Securities  shall be issued or sold for
     cash, the consideration  received therefor shall be deemed to be the amount
     received by the Company therefor, after deducting any expenses incurred and
     any underwriting or similar  commissions,  compensation or concessions paid
     or allowed by the Company in connection with such issue or sale.

               (vii)  In  case  any  shares  of  Common  Stock  or   Convertible
     Securities or any rights or options to subscribe for, purchase or otherwise
     acquire any Common Stock or Convertible  Securities shall be issued or sold
     for a consideration other than cash (or a consideration which includes cash
     and other assets) then, for the purpose of this paragraph (c), the Board of
     Directors of the Company  shall  promptly  determine the fair value of such
     consideration,  and such Common Stock,  Convertible  Securities,  rights or
     options  shall be deemed  to have  been  issued or sold on the date of such
     determination  in good faith.  Such value shall not be more than the amount
     at which such  consideration  is  recorded  in the books of the Company for
     accounting purposes except in the case of an acquisition accounted for on a
     pooling  of  interest  basis.  In case  any  Common  Stock  or  Convertible
     Securities or any rights or options to subscribe for, purchase or otherwise
     acquire any Common Stock or Convertible  Securities shall be issued or sold
     together  with other stock or securities or other assets of the Company for
     a  consideration  which covers both,  the Board of Directors of the Company
     shall promptly  determine in good faith what part of the  consideration  so
     received is to be deemed to be the  consideration  for the issue or sale of
     such Common Stock or Convertible Securities or such rights or options.

               The Company  covenants and agrees that,  should any determination
     of fair value of consideration or of allocation of consideration be made by
     the Board of Directors of the Company, pursuant to this subparagraph (vii),
     it  will,   not  less  than   seven  (7)  days  after  any  and  each  such
     determination, deliver to the Holder of this Debenture a certificate signed
     by the  President  or a Vice  President  and the  Treasurer or an Assistant
     Treasurer of the Company reciting such value as thus determined and setting
     forth  the 

<PAGE>

     nature of the transaction for which such  determination  was required to be
     made,  the nature of any  consideration,  other than cash, for which Common
     Stock,  Convertible  Securities,  rights or options  have been or are to be
     issued,  the basis for its valuation,  the number of shares of Common Stock
     which have been or are to be issued,  and a description of any  Convertible
     Securities,  rights  or  options  which  have  been  or are  to be  issued,
     including their number, amount and terms.

               (viii) In case the Company  shall take a record of the holders of
     shares of its stock of any class for the purpose of  entitling  them (a) to
     receive  a  dividend  or a  distribution  payable  in  Common  Stock  or in
     Convertible  Securities,  or (b) to  subscribe  for,  purchase or otherwise
     acquire Common Stock or Convertible Securities, then such record date shall
     be deemed to be the date of the issue or sale of the Common Stock issued or
     sold or  deemed to have been  issued or sold upon the  declaration  of such
     dividend  or the  making  of such  other  distribution,  or the date of the
     granting of such rights of subscription,  purchase or other acquisition, as
     the case may be.

               (ix) The  number of shares of  Common  Stock  outstanding  at any
     given time shall include shares  issuable in respect of scrip  certificates
     issued in lieu of fractions of shares of Common  Stock,  but shall  exclude
     shares in the treasury of the Company.

               (x) Following  each  computation or  readjustment  of a Pro Forma
     Adjusted  Trigger  Price  as  provided  in this  paragraph (c),  the  newly
     computed or  adjusted  Pro Forma  Adjusted  Trigger  Price shall  remain in
     effect until a further  computation or readjustment  thereof is required by
     this paragraph (c).

               (xi) In case at any time or from time to time after the  Issuance
     Date the  holders of the Common  Stock of the  Company of any class (or any
     other shares of stock or other  securities at the time  receivable upon the
     exercise of this Debenture) shall have received, or, on or after the record
     date  fixed for the  determination  of  eligible  stockholders,  shall have
     become entitled to receive:

                    (A)  other  or  additional  stock  or  other  securities  or
          property (other than cash) by way of dividend;

                    (B) any cash  paid or  payable  out of  capital  or  paid-in
          surplus or surplus created as a result of a revaluation of property by
          way of dividend; or

                    (C) other or additional (or less) stock or other  securities
          or  property  (including  cash)  by  way  of  stock-split,   spin-off,
          split-off,  split-up,  reclassification,   combination  of  shares  or
          similar corporate rearrangement;

<PAGE>

(other than additional  shares of Common Stock issued to holders of Common Stock
as a stock  dividend or  stock-split,  adjustments  in respect of which shall be
covered by the provisions of this  paragraph (c)),  then in each case the Holder
of this  Debenture,  upon the  conversion  hereof as provided  in  paragraph (a)
hereof, shall be entitled to receive, in lieu of, or in addition to, as the case
may be, the shares theretofore receivable upon the conversion of this Debenture,
the amount of stock or other securities or property (including cash in the cases
referred  to in clauses (B) and (C) above)  which such Holder  would hold on the
date of such  exercise  if, on the  Issuance  Date,  he,  she or it had been the
holder of record of the  number of shares of Common  Stock of the  Company  into
which this Debenture is convertible and had  thereafter,  during the period from
the Issuance Date to and including  the date of such  conversion,  retained such
shares  and/or all other or  additional  (or less) stock or other  securities or
property  (including cash in the cases referred to in clauses (B) and (C) above)
receivable by him, her or it as aforesaid  during such period,  giving effect to
all adjustments  called for during such period by paragraph (c) and subparagraph
(xii) hereof.

               (xii) In case of any  reorganization of the Company (or any other
     corporation  the  stock  or  other  securities  of  which  are at the  time
     deliverable on the conversion of this Debenture) after the date hereof,  or
     in case, after such date, the Company (or any such other corporation) shall
     consolidate  with or  merge  into  another  corporation  or  convey  all or
     substantially all its assets to another corporation,  then and in each such
     case the Holder of this Debenture,  upon the conversion  hereof as provided
     in  paragraph (a)  hereof,  at any  time  after  the  consummation  of such
     reorganization,  consolidation,  merger or conveyance, shall be entitled to
     receive  the stock or other  securities  or  property  to which such Holder
     would  have  been  entitled  upon  such  consummation  if such  Holder  had
     converted this Debenture  immediately prior thereto, all subject to further
     adjustments  as provided for herein;  in each such case,  the terms of this
     Debenture shall be applicable to the shares of stock or other securities or
     property  receivable  upon the  conversion  of this  Debenture  after  such
     consummation.

               (xiii) The  Company  will not,  by  amendment  of its  charter or
     through reorganization,  consolidation, merger, dissolution, sale of assets
     or any other  voluntary  action,  avoid or seek to avoid the  observance or
     performance of any of the terms of this Debenture, but will at all times in
     good faith  assist in the  carrying out of all such terms and in the taking
     of all such action as may be necessary or  appropriate  in order to protect
     the rights of the  Holder  hereof  against  dilution  or other  impairment.
     Without  limiting the  generality  of the  foregoing,  the Company will not
     increase  the  par  value  of any  shares  of  stock  receivable  upon  the
     conversion of this Debenture  above the amount  payable  therefor upon such
     exercise, and at all times will take all such action as may be necessary or
     appropriate  in order that the Company may validly and legally  issue fully
     paid and non-assessable stock upon the conversion of this Debenture.

<PAGE>

               (xiv) In each case of an  adjustment  in the  number of shares of
     Common  Stock or other  stock,  securities  or property  receivable  on the
     conversion  of  this  Debenture,  at the  request  of the  Holder  of  this
     Debenture  the  Company at its expense  shall  promptly  cause  independent
     public  accountants  of recognized  standing,  selected by the Company,  to
     compute such  adjustment in accordance with the terms of this Debenture and
     prepare a certificate  setting forth such  adjustment and showing in detail
     the facts upon which such adjustment is based, including a statement of (A)
     the  consideration  received  or to be  received  by the  Company  for  any
     additional shares issued or sold or deemed to have been issued or sold, (B)
     the  number  of  shares  of  Common  Stock  outstanding  or  deemed  to  be
     outstanding and (C) the Pro Forma Adjusted  Trigger Price. The Company will
     forthwith  mail a copy of  each  such  certificate  to the  Holder  of this
     Debenture.

               (xv) In case:

                    (A) the  Company  shall take a record of the  holders of its
          Common  Stock (or other stock or  securities  at the time  deliverable
          upon the conversion of this Debenture) for the purpose of entitling or
          enabling  them to receive  any  dividend  (other  than a cash or stock
          dividend  at the  same  rate as the  rate of the  last  cash or  stock
          dividend  theretofore paid) or other distribution,  or to exercise any
          preemptive right pursuant to the Company's charter,  or to receive any
          right to subscribe for or purchase any shares of stock of any class or
          any other securities, or to receive any other right; or

                    (B) of  any  capital  reorganization  of  the  Company,  any
          reclassification   of  the   capital   stock  of  the   Company,   any
          consolidation   or  merger  of  the  Company   with  or  into  another
          corporation,  or any  conveyance  of all or  substantially  all of the
          assets of the Company to another corporation; or

                    (C) of the voluntary or involuntary dissolution, liquidation
          or winding up of the Company;

then,  and in each such case, the Company will mail or cause to be mailed to the
Holder of this Debenture a notice  specifying,  as the case may be, (i) the date
on which a record is to be taken for the purpose of such dividend,  distribution
or right, and stating the amount and character of such dividend, distribution or
right,  or  (ii)  the  date  on  which  such  reorganization,  reclassification,
consolidation,  merger, conveyance, dissolution, liquidation or winding up is to
take  place,  and the times,  if any is to be fixed,  as of which the holders of
record  of  Common  Stock  (or  such  other  stock  or  securities  at the  time
deliverable  upon the exercise of this Debenture)  shall be entitled to exchange
their  shares of Common  Stock of any class (or such other stock or  securities)
for   

<PAGE>



reclassification, consolidation, merger, conveyance, dissolution, liquidation or
winding up or (iii) the amount and  character  of the stock or other  securities
proposed to be issued or granted,  the date of such  proposed  issuance or grant
and the persons or class of persons to whom such stock or other  securities  are
to be offered,  issued or granted.  Such notice  shall be mailed at least thirty
(30) days prior to the date therein specified.

                    (xvi)  The  Company  will  at all  times  reserve  and  keep
          available,  solely for issuance and delivery  upon the  conversion  of
          this  Debenture  and other similar  Debentures,  such shares of Common
          Stock and other  stock,  securities  and property as from time to time
          shall be issuable  upon the exercise of this  Debenture  and all other
          similar Debentures at the time outstanding.

                    (xvii) Upon receipt of evidence  reasonably  satisfactory to
          the Company of the loss,  theft,  destruction  or  mutilation  of this
          Debenture  and (in the  case  of  loss,  theft  or  destruction)  upon
          delivery  of  an   indemnity   agreement   in  an  amount   reasonably
          satisfactory to it, or (in the case of mutilation)  upon surrender and
          cancellation  thereof,  the Company will issue, in lieu thereof, a new
          Debenture of like tenor.

                    (xviii)  (A) On or prior to October  27,  1997,  the Company
          will file a registration statement ("Registration Statement") with the
          Securities  and  Exchange  Commission  ("SEC")  covering the shares of
          Common  Stock  issuable  upon  conversion  of the  Debentures  and any
          Accrued Interest Debentures (and covering such other securities as the
          Company  shall  determine  in  its  sole   discretion)   (collectively
          "Registrable Securities"),  and will use its best efforts to cause the
          Registration  Statement  to  become  effective  on  or  prior  to  the
          ninetieth day after such filing and to keep the Registration Statement
          effective  until the  earlier  of (i) seven  years from the date it is
          declared  effective  by  the  SEC,  or  (ii)  the  sale  of all of the
          Registrable Securities.

                         (B) The following provisions shall be applicable to the
          Registration Statement:

                         (aa) The Company will use its best efforts to cause the
               Registration   Statement  to  become  effective  as  promptly  as
               possible,  and if any stop  order  shall be  issued by the SEC in
               connection  therewith to use its reasonable efforts to obtain the
               removal  of  such  order.  Following  the  effective  date of the
               Registration  Statement,  the Company shall,  upon the request of
               the Holder,  forthwith supply such reasonable number of copies of
               the Registration Statement, preliminary prospectus and prospectus
               meeting  the   requirements  of  the  Act,  and  other  documents
               necessary or incidental to a public  offering of the  Registrable
               Securities,  as shall be  

<PAGE>

               reasonably requested by the Holder to permit the Holder to make a
               public  distribution of its, his or her  Registrable  Securities;
               provided,  however, that by accepting this Debenture,  the Holder
               agrees, if requested by the managing underwriter(s) in connection
               with an  underwritten  public  offering of the  Company's  equity
               securities,  to  enter  into  a  customary  agreement  with  such
               managing underwriter(s) not to offer for sale or sell its, his or
               her  Registrable  Securities  for  up  to  180  days  after  such
               offering.  The Company will use its reasonable efforts to qualify
               the Registrable  Securities for sale in such states as the holder
               of Registrable Securities shall reasonably request, provided that
               no such qualification will be required in any jurisdiction where,
               solely as a result  thereof,  the  Company  would be  subject  to
               service of general process or to taxation or  qualification  as a
               foreign  corporation  doing  business in such  jurisdiction.  The
               obligations of the Company hereunder with respect to the Holder's
               Registrable  Securities are expressly conditioned on the Holder's
               furnishing to the Company such appropriate information concerning
               the Holder, the Holder's Registrable  Securities and the terms of
               the  Holder's  offering  of such  Registrable  Securities  as the
               Company may reasonably request.

                         (bb) The  Company  shall pay all  expenses  incurred in
               complying  with  the  provisions  of this  subparagraph  (xviii),
               including,  without limitation,  all registration and filing fees
               (including  all  expenses  incident to filing  with the  National
               Association of Securities Dealers, Inc.), printing expenses, fees
               and  disbursements of counsel to the Company,  securities law and
               blue sky fees and  expenses  and the  expenses of any regular and
               special audits incident to or required by any such  registration.
               All underwriting  discounts and selling commissions applicable to
               the sales of the Registrable Securities, and any state or federal
               transfer   taxes  payable  with  respect  to  the  sales  of  the
               Registrable  Securities and all fees and disbursements of counsel
               for the Holder,  if any, in each case arising in connection  with
               registration  of the Registrable  Securities  shall be payable by
               the Holder.

                         (cc)  In  connection  with  the   registration  of  the
               Registrable Securities pursuant to this subparagraph (xviii), the
               Company  shall  indemnify  and  hold  harmless  the  Holder,  its
               affiliates,  officers, directors, partners, employees, agents and
               representatives,  each  person,  if any,  who controls the Holder
               within the meaning of the Securities Act of 1933, as amended (the
               "Securities  Act"),  or the  Securities  Exchange Act of 1934, as
               amended  (the  "Exchange  Act"),  any  person  deemed  to  be  an
               underwriter of the Registrable Securities and any person claiming
               by  or  through  any  of 

<PAGE>

               them (collectively,  the "Indemnified  Persons") from and against
               all losses, claims, damages,  expenses or liabilities (or actions
               in respect  thereof)  arising out of or are based upon any untrue
               statement of any  material  fact  contained  in the  Registration
               Statement  or  alleged   untrue   statement,   under  which  such
               securities  were   registered   under  the  Securities  Act,  any
               preliminary  prospectus or final prospectus contained therein, or
               any amendment or supplement thereto, or arise out of or are based
               upon the omission to state therein a material fact required to be
               stated therein or necessary to make the statements  made therein,
               in light of the  circumstances  under  which  they are made,  not
               misleading,  or any  violation  by the Company of the  Securities
               Act,  the  Exchange  Act or  state  securities  or blue  sky laws
               applicable  to the  Company  and  relating  to action or inaction
               required of the Company in connection  with such  registration or
               qualification  under such state  securities or blue sky laws; and
               will reimburse the Indemnified Persons for any legal or any other
               expenses   reasonably   incurred  by  them  in  connection   with
               investigating  or  defending  any  such  loss,   claim,   damage,
               liability or action; provided, however, that the Company will not
               be  liable  in any such  case to any  Indemnified  Person  to the
               extent that any such loss, claim,  damage or liability arises out
               of or is based upon an untrue  statement or omission  made in the
               Registration Statement, said preliminary prospectus or said final
               prospectus  or  said  amendment  or  supplement  or any  document
               incident  thereto in reliance upon and in conformity with written
               information  furnished  to the  Company  by or on  behalf  of the
               Holder.

                         (dd) The Holder will  indemnify  and hold  harmless the
               Company and each person,  if any, who controls the Company within
               the  meaning of the  Securities  Act or the  Exchange  Act,  each
               officer of the Company who signs the  Registration  Statement and
               each  director of the  Company  from and against any and all such
               losses,  claims,  damages or liabilities  arising from any untrue
               statement in, or omission from, the Registration  Statement,  any
               such preliminary or final prospectus, amendment, or supplement or
               document incident thereto if the statement or omission in respect
               of which such loss,  claim,  damage or  liability is asserted was
               made  in  reliance  upon  and  in  conformity  with   information
               furnished in writing to the Company by or on behalf of the Holder
               for use in connection  with the  preparation of the  Registration
               Statement or such prospectus or amendment or supplement thereof.

                         (ee) The  reimbursements  required by clauses  (cc) and
               (dd) shall be made by periodic  payments during the course of the
               investigation  

<PAGE>
               or defense as and when bills are  received or expenses  incurred;
               provided,  however,  that to the extent that an indemnified party
               receives periodic payments for legal or other expenses during the
               course  of  an   investigation   or   defense,   and  such  party
               subsequently  received  payments for such expenses from any other
               parties to the  proceeding,  such  payments  shall be used by the
               indemnified  party to reimburse the  indemnifying  party for such
               periodic  payments.  Any party which proposes to assert the right
               to be indemnified under clause (cc) or (dd) will,  promptly after
               receipt  of  notice  of  commencement  of  any  action,  suit  or
               proceeding  against  such party in respect of which a claim is to
               be made against any indemnified party hereunder, notify each such
               indemnifying  party of the  commencement of such action,  suit or
               proceeding,  enclosing  a copy  of all  papers  served,  but  the
               failure to so notify such indemnifying  party of any such action,
               suit or proceeding shall not relieve the indemnifying  party from
               any  obligation  which  it  may  have  to any  indemnified  party
               hereunder  unless  and only to the extent  that the  indemnifying
               party is  prejudiced  by said  lack of  notice.  In case any such
               action,   suit  or  proceeding   shall  be  brought  against  any
               indemnified  party and it shall notify the indemnifying  party of
               the  commencement   thereof,  the  indemnifying  party  shall  be
               entitled to participate in and, to the extent that it shall wish,
               jointly with any other indemnifying party similarly notified,  to
               assume the defense  thereof,  with counsel  satisfactory  to such
               indemnified  party, and after notice from the indemnifying  party
               to such  indemnified  party  of its  election  so to  assume  the
               defense thereof,  the  indemnifying  party shall not be liable to
               such indemnified party for any legal or other expense, other than
               reasonable costs of investigation  subsequently  incurred by such
               indemnified  party in connection  with the defense  thereof.  The
               indemnified  party shall have the right to employ its own counsel
               in any such action,  but the reasonable fees and expenses of such
               counsel shall be at the expense of such indemnified  party,  when
               and as  incurred,  unless (A) the  employment  of counsel by such
               indemnified party has been authorized by the indemnifying  party,
               (B) the  indemnified  party has  reasonably  concluded  (based on
               advice of counsel), that there may be legal defenses available to
               it that are different  from or in addition to those  available to
               the  indemnifying  party,  (C) the  indemnified  party shall have
               reasonably  concluded (based on advice of counsel) that there may
               be a conflict of interest between the indemnifying  party and the
               indemnified  party in the  conduct of defense of such  action (in
               which  case the  indemnifying  party  shall not have the right to
               direct the  defense of such  action on behalf of the  indemnified
               party),  or (D) the  indemnifying  party  shall  not in fact have
               employed  counsel to assume the defense of such action  within 15
               days after  receipt  of notice of such  action.  

<PAGE>

               An  indemnifying  party shall not be liable for any settlement or
               any action or claim effected without its consent, which shall not
               be unreasonably withheld.

                         (ff)  If  the  indemnification  provided  for  in  this
               subparagraph  (xviii) is  unavailable  to any  indemnified  party
               hereunder in respect of any losses, claims, damages,  liabilities
               or expenses referred to therein,  then the indemnifying party, in
               lieu of indemnifying such indemnified  party, shall contribute to
               the amount paid or payable by such indemnified  party as a result
               of such losses, claims, damages,  liabilities or expenses in such
               proportion as is appropriate to reflect the relative fault of the
               indemnifying party and indemnified parties in connection with the
               actions   that   resulted  in  such  losses,   claims,   damages,
               liabilities or expenses,  as well as any other relevant equitable
               considerations. The relative fault of such indemnifying party and
               indemnified  parties  shall be  determined by reference to, among
               other  things,  whether  any action in  question,  including  any
               untrue or alleged untrue statement of a material fact or omission
               or alleged  omission to state a material  fact, has been made by,
               or relates to information supplied by, such indemnifying party or
               indemnified parties, and the parties' relative intent, knowledge,
               access to information  and opportunity to correct or prevent such
               action.  The amount paid or payable by a party as a result of the
               losses,  claims,  damages,  liabilities and expenses  referred to
               above shall be deemed to include,  subject to the limitations set
               forth  herein,  any legal or other  fees or  expenses  reasonably
               incurred by such party in connection  with any  investigation  or
               proceeding.

                         (gg) The Company and the Holder agree that it would not
               be just and  equitable  if  contribution  pursuant to clause (ff)
               were  determined by pro rata allocation or by any other method of
               allocation   that  does  not  take   account  of  the   equitable
               considerations   referred   to  in  the   immediately   preceding
               paragraph.  Notwithstanding  any other  provision  hereof,  in no
               event shall the contribution  obligation of the Holder be greater
               in  amount  than  the  excess  of (A) the  dollar  amount  of net
               proceeds  received by the Holder upon the sale of the  securities
               giving rise to such  contribution  obligation over (B) the dollar
               amount of any damages that the Holder has otherwise been required
               to pay by reason of the untrue or  alleged  untrue  statement  or
               omission or alleged omission giving rise to such  obligation.  No
               person guilty of fraudulent misrepresentation (within the meaning
               of  Section 11(f)  of the  Securities  Act) shall be  entitled to
               contribution   from  any  person  who  was  not  guilty  of  such
               fraudulent misrepresentation.

<PAGE>

                         (hh) Neither the filing of the  Registration  Statement
               by the Company  pursuant to this  Agreement nor the making of any
               request  for  prospectuses  by the Holder  shall  impose upon the
               Holder any obligation to convert his, her or its Debentures or to
               sell his, her or its Registrable Securities.

                         (ii)  The  Holder,  upon  receipt  of  notice  from the
               Company   that  an  event   has   occurred   which   requires   a
               post-effective  amendment  to  the  Registration  Statement  or a
               supplement to the  prospectus  included  therein,  shall promptly
               discontinue  the sale of his, her or its  Registrable  Securities
               until the  Holder  receives a copy of a  supplemented  or amended
               prospectus  from the Company,  which the Company shall provide as
               soon as practicable after such notice.

                         (C) In the event (a) the Registration  Statement is not
          filed by the Company with the SEC on or prior to October 27, 1997,  or
          (b) the Registration  Statement has not been declared effective by the
          SEC on or prior to January 25, 1998,  the annual  interest rate on the
          Debentures  shall be the rate per annum ("Default  Rate") which is 13%
          increased by one and one-half percent (1-1/2%) per annum for the first
          three (3) months  immediately  following the expiration of such ninety
          (90) day period or one hundred  eighty  (180) day period,  as the case
          may be, and by an additional  one-half of one percent (1/2%) per annum
          at the beginning of each subsequent thirty (30) day period thereafter,
          until such time as the requirements of clause (a) or (b) above, as the
          case may be, have been  satisfied,  at which time all increases in the
          interest rate borne by the Debentures  resulting from the operation of
          this  sentence  shall  terminate  and the  interest  rate borne by the
          Debentures  shall revert to the rate that otherwise would be in effect
          but for the operation of this sentence;  provided, however, that in no
          event shall the interest rate borne by the Debentures exceed seventeen
          percent (17%) per annum pursuant to this sentence.

     7.   Covenants.

          (a)      Affirmative Covenants:  The Company will, and with respect to
the agreements set forth in subsections (i) through (viii) hereof, will cause 
each subsidiary to:

               (i) with respect to its properties, assets and business, maintain
     insurance against loss or damage,  to the extent that property,  assets and
     businesses  of similar  character  are  usually  so  insured  by  companies
     similarly situated and operating like properties, assets or businesses with
     responsible  insurance companies  satisfactory to the 

<PAGE>

     Majority  Holders  said  insurance to indicate the Agent (as defined in the
     Security Agreement) as an additional insured;

               (ii) duly pay and discharge all taxes or other claims which might
     become a lien upon any of its  properties  except to the  extent  that such
     items are being in good faith appropriately contested;

               (iii) maintain,  preserve and keep its properties in good repair,
     working order and condition, and make all reasonable repairs, replacements,
     additions, betterments and improvements thereto;

               (iv) conduct its business in substantially the same manner and in
     substantially  the same  fields  as such  business  is now  carried  on and
     conducted;

               (v) comply with all statutes,  rules and regulations and maintain
     its corporate existence;

               (vi) provide the Holder with the following financial information:

                    (A) annually, as soon as available,  but in any event within
          one hundred  twenty (120) days after the last day of each fiscal year,
          audited financial statements,  including balance sheets as of the last
          day of the fiscal year and statements of income and retained  earnings
          and changes in financial  condition for such fiscal year each prepared
          in  accordance   with  generally   accepted   accounting   principles,
          consistently  applied  ("GAAP")  for the period  and prior  periods by
          independent Certified Public Accountants  satisfactory to the Majority
          Holders;

                    (B) as soon as available, but in any event within forty-five
          (45) days after the end of each fiscal  quarter,  internally  prepared
          financial  statements of the Company each prepared in accordance  with
          GAAP and jobs-in-progress reports for said period and prior periods;

                    (C)  within  a  reasonable  time  after  a  written  request
          therefor,  such other  financial data or information as the Holder may
          reasonably request from time to time;

                    (D) at the same time as it delivers the financial statements
          required  under the provisions of  subsections  (A) and (B) hereof,  a
          certificate  signed  by the  president  or  the  chief  financial,  or
          accounting,  officer of the  Company,  to the effect  that no Event of
          Default  hereunder or material  default  under any other  agreement to
          which the Company is a party or by which it is bound,  or by which

<PAGE>          

          any of its  properties or assets may be affected,  and no event which,
          with the  giving  of  notice  or the  lapse of  time,  or both,  would
          constitute such an Event of Default, has occurred;

                    (E) on a monthly  basis,  no later than the tenth (10th) day
          after each such month,  backlog reports and accounts receivable agings
          of the Company;

               (vii) permit the Holder to make or cause to be made,  inspections
     and  audits of any books,  records  and  papers of the  Company  and of any
     parent or  subsidiary  thereof and to make  extracts  therefrom at all such
     reasonable times and as often as the Holder may reasonably require;

               (viii)  immediately  give  notice to the Holder  that an Event of
     Default has occurred or that an event  which,  with the giving of notice or
     lapse of time, or both, would constitute an Event of Default,  has occurred
     and  specifying the action which the Company has taken and proposes to take
     with respect thereto.

          (b)   Financial Covenants:

               (i) At the end of each fiscal quarter, the Company shall maintain
     a  Tangible  Net  Worth  of  (-3,042,322)  or  greater  (as  calculated  in
     accordance with GAAP). For purposes hereof "Tangible Net Worth" shall mean,
     at any date,  (i) the net book value of assets (other than patents,  patent
     rights, trademarks, trade names, franchises, copyrights, licenses, permits,
     goodwill and other intangible  assets classified as such in accordance with
     GAAP) after all appropriate adjustments in accordance with GAAP (including,
     without  limitation,  reserves  for  doubtful  receivables,   obsolescence,
     depreciation and amortization) plus (ii) subordinated indebtedness, in each
     case computed in accordance with GAAP; and

               (ii) At the end of each fiscal quarter,  the Company shall report
     a net income (gross income less taxes and extraordinary  items) of not less
     than $1.00.

          (c)   Negative Covenants:  The Company will not, and will not permit 
any subsidiary to:

               (i) create,  incur,  assume or suffer to exist any  liability for
     borrowed money,  except (A) indebtedness to the Bank or any other financial
     institution   constituting   "Senior  Debt"  hereunder;   (B)  indebtedness
     outstanding  on  the  date  hereof;  (C)  indebtedness  represented  by the
     Company's  13% Senior  Subordinated  Interest  Note (the  "Note")  (and any
     replacement  Note or Notes  issued upon  transfer or exchange of the Note);
     (D)  indebtedness  represented  by  the  Debentures  (and  any  replacement
     Debenture  or   Debentures   issued  upon   transfer  or  exchange  of  the
     Debentures);   (E)   indebtedness

<PAGE>

     represented by the Accrued Interest Debentures (and any replacement Accrued
     Interest  Debenture or Accrued Interest  Debentures issued upon transfer or
     exchange of the Accrued Interest Debentures);  (F) indebtedness represented
     by the Class A Debentures (and any replacement Class A Debenture or Class A
     Debentures issued upon transfer or exchange of the Class A Debentures); (G)
     indebtedness  represented by the Class A Accrued  Interest  Debentures (and
     any  replacement  Class A  Accrued  Interest  Debenture  or Class A Accrued
     Interest Debentures issued upon transfer or exchange of the Class A Accrued
     Interest  Debentures);  and  (H)  other  indebtedness  for  borrowed  money
     (whether or not  constituting  a refinancing of existing  indebtedness)  so
     long  as (x)  such  indebtedness  is not  secured  by  collateral  securing
     repayment of the  Debentures,  (y) such  indebtedness  contains  provisions
     reasonably  satisfactory to the Majority Holders  subordinating the payment
     of principal  and interest  thereon to the prior  payment of principal  and
     interest on the Debentures,  and (z) the incurrence of which will not cause
     an Event of Default,  or an event which with notice or the lapse of time or
     both  would  constitute  an  Event  of  Default,  hereunder  (collectively,
     "Permitted Indebtedness");

               (ii)  create,  incur,  assume or suffer to exist,  any  mortgage,
     pledge,  lien or encumbrance of or upon or security interest in, any of its
     property or assets now owned or hereafter  acquired  except (A)  mortgages,
     liens, pledges and security interests securing Permitted Indebtedness;  (B)
     other  liens,  charges and  encumbrances  incidental  to the conduct of its
     business or the ownership of its property and assets which are not incurred
     in  connection  with the borrowing of money or the obtaining of advances or
     credit and which do not materially  impair the use thereof in the operation
     of its business;  (C) liens for taxes or other  governmental  charges which
     are not delinquent or which are being contested in good faith and for which
     a reserve shall have been  established  in accordance  with GAAP; (D) liens
     granted to secure  purchase  money  financing of  equipment,  provided such
     liens are  limited  to the  equipment  financed;  and (E) liens  granted to
     refinance  unencumbered  equipment  provided  such liens are limited to the
     equipment  refinanced  and the incurrence of which will not cause a default
     hereunder or in any Senior Debt;

               (iii) assume,  endorse,  be or become liable for or guarantee the
     obligations  of any other person  except by the  endorsement  of negotiable
     instruments for deposit or collection in the ordinary course of business;

               (iv)  (A)  terminate  any  pension  plan so as to  result  in any
     material liability to The Pension Benefit Guaranty Corporation  established
     pursuant to Subtitle A of Title IV of ERISA (the "PBGC"),  (B) engage in or
     permit any person to engage in any "prohibited  transaction" (as defined in
     Section 406 of ERISA or Section 4975 of the Internal  Revenue Code of 1986,
     as amended)  involving  any pension plan which would subject the Company to
     any material tax, penalty or other liability,  (C) incur or suffer to 

<PAGE>

     exist any material  "accumulated funding deficiency" (as defined in Section
     302 of ERISA),  whether or not waived,  involving  any pension plan, or (D)
     allow or suffer to exist any event or condition,  which presents a material
     risk of incurring a material liability to the PBGC by reason of termination
     of any pension plan;

               (v)  amend,  supplement  or  modify  the  terms  of  the  Subject
     Securities  or increase the  outstanding  amount of any Subject  Securities
     (excluding awards granted under the Plan or under an incentive compensation
     plan or arrangement  approved by the Company's Board of Directors or by the
     Compensation  Committee of the Company's  Board of  Directors)  without the
     prior consent of the Majority Holders;

               (vi) enter into any merger or  consolidation  unless the  Company
     shall be the  surviving  entity in any such  merger or  consolidation,  and
     after  giving  effect to the  transaction  no Event of Default and no event
     which with the giving of notice or passage of time or both would constitute
     an Event of Default  shall have occurred and be  continuing,  or liquidate,
     wind-up or dissolve itself or sell,  transfer or lease or otherwise dispose
     of all or any substantial part of its assets;

               (vii) lend or advance  money,  credit or property to or invest in
     (by  capital   contribution,   loan,   purchase  or  otherwise)  any  firm,
     corporation,  or other  person  except  (A)  investments  in United  States
     Government  obligations and certificates of deposit of any bank institution
     with  combined  capital  and  surplus of at least  $200,000,000,  (B) trade
     credit,  (C) security  deposits,  or acquire or  otherwise  cause any other
     entity to become a  subsidiary  of the  Company  (as used  herein  the term
     "subsidiary"   means  any  corporation  or  other   organization,   whether
     incorporated  or  unincorporated,   of  which  the  Company  or  any  other
     subsidiary  of the  Company  beneficially  owns a majority of the voting or
     economic  interests),  (D) loans made to  Murray H.  Feigenbaum  and Jerome
     Deutsch in the aggregate  principal amount of $162,950 existing on the date
     hereof,  and (E) loans made to Norman M. Phipps and Michael  Gaffney in the
     aggregate amount of $675,000 existing on the date hereof;

               (viii) declare or pay any dividends or  distributions  on account
     of its capital stock or purchase,  redeem,  retire or otherwise acquire any
     of its capital stock or any securities convertible into,  exchangeable for,
     or giving any person the right to acquire or otherwise  subscribe  for, any
     shares of the Company's capital stock;  provided,  however, that so long as
     no Event of Default or event which, with the giving of notice, the lapse of
     time, or both would  constitute an Event of Default  hereunder has occurred
     and is continuing,  the Company may pay regular quarterly  dividends on the
     Preferred Stock in accordance with the terms thereof; or

<PAGE>

               (ix)  engage in any  transaction  with any  person or entity  who
     directly or indirectly,  through one or more intermediaries,  controls,  is
     controlled   by,  or  is  under  common   control  with,  the  Company  (an
     "Affiliate"),  other  than  director  and  compensation  arrangements  with
     Affiliates  serving as officers and/or directors of the Company approved by
     the  Company's  Board  of  Directors  and  other  than   transactions  with
     Affiliates  entered into in the ordinary  course of business on terms which
     are at least as favorable to the Company as those  available from unrelated
     third parties.  As used herein,  the term "control"  means the  possession,
     directly or  indirectly,  of the power to direct or cause the  direction of
     the management and policies of the Company,  whether  through the ownership
     of voting securities,  by contract or otherwise, and the terms "controlled"
     and "controlling" have meanings correlative thereto.

     8.  Events of Default.

         (a)  Definition.   For  the  purposes  of  this Debenture, an Event of 
Default hereunder will be deemed to have occurred if:

               (i)  the  Company  fails  to pay  the  principal  amount  of this
     Debenture  when  due  (whether  upon the Due  Date,  upon  acceleration  or
     otherwise),  whether  or not such  payment  is  prohibited  by  paragraph 4
     hereof;

               (ii) the Company fails to pay any interest, premium or penalty on
     this  Debenture when due and such failure has continued for a period of ten
     (10) days;

               (iii) the Company fails to perform or observe the  provisions set
     forth in Paragraphs 7(b) or 7(c) hereof;

               (iv) the  Company  fails to  perform  or  observe  any  provision
     contained in this  Debenture or the  Security  Agreement  (other than those
     specifically  covered by the other provisions of this  paragraph 8(a)) and,
     if such failure is capable of being cured,  such  failure  continues  for a
     period of 30 days after the Company's receipt of written notice thereof;

               (v) the Company  shall have failed to pay when due any amount due
     and owing under any  indebtedness  of the Company for borrowed money or any
     other  default or event of  default  shall  have  occurred  (and shall have
     continued  beyond the expiration of any applicable  grace period) under any
     indebtedness  of the Company  for  borrowed  money  which would  permit the
     holder thereof to accelerate the maturity  thereof or there shall have been
     an acceleration  of the stated maturity of any  indebtedness of the Company
     for borrowed money;

<PAGE>
               (vi) the Security Agreement shall at any time after its execution
     and delivery and for any reason cease to  constitute a valid and  perfected
     lien and security interest in and to the Collateral (as defined therein) or
     the Company  shall take any position  inconsistent  therewith or any of the
     provisions of the Security Agreement that permit the Holder to exercise its
     remedies thereunder cease to be in full force and effect;

               (vii)  the  Company  makes  an  assignment  for  the  benefit  of
     creditors or admits in writing its inability to pay its debts  generally as
     they become due;  or an order,  judgment or decree is entered  adjudicating
     the Company as bankrupt or insolvent;  or any order for relief with respect
     to the Company is entered under the Federal Bankruptcy Code; or the Company
     petitions or applies to any tribunal  for the  appointment  of a custodian,
     trustee,  receiver or liquidator of the Company or of any substantial  part
     of the assets of the Company,  or commences any proceeding  relating to the
     Company  under any  bankruptcy,  reorganization,  arrangement,  insolvency,
     readjustment of debt,  dissolution or liquidation  law of any  jurisdiction
     ("Insolvency Event or Proceeding");  or any such petition or application is
     filed, or any such proceeding is commenced,  against the Company and either
     (y) the Company by any act indicates its approval thereof, consents thereto
     or acquiescence  therein or (z) such petition  application or proceeding is
     not dismissed within 60 days;

               (viii)  a  final  judgment  which  in the  aggregate  with  other
     outstanding  final judgments  against the Company exceeds $250,000 shall be
     rendered  against the Company and within 90 days after entry thereof,  such
     judgment is not discharged or execution  thereof stayed pending appeal,  or
     within 90 days after the  expiration  of such stay,  such  judgment  is not
     discharged;

               (ix) any  representation  or warranty  made by the Company in the
     Unit Purchase  Agreement,  dated March 7,  1996 between the Company and the
     original  Holder of this Debenture,  the Security  Documents (as defined in
     such Unit  Purchase  Agreement),  or any other  certificate  or  instrument
     delivered in  connection  therewith  shall have been untrue in any material
     respect when made; or

               (x) the Registration Statement shall not have become effective on
     or prior to April 25, 1998.

         (b)  Consequences of Events of Default.

               (i) If any Event of Default  (other  than the type  described  in
     subparagraph 8(a)(vii)  above)  has  occurred,  the  Holder or  Holders  of
     Debentures  representing  a majority of the aggregate  principal  amount of
     Debentures then outstanding (the "Majority Holders") may demand (by written
     notice delivered to the Company) 

<PAGE>

     immediate payment of all or any portion of the outstanding principal amount
     of the Debentures owed by such Holder or Holders.  If such Majority Holders
     demand immediate payment of all or any portion of such Holder's or Holders'
     Debentures,  the Company will, to the extent permitted under the provisions
     of  paragraph  4 hereof,  immediately  pay to such  Holder or  Holders  the
     principal  amount of the  Debentures  requested  to be paid  (plus  accrued
     interest  hereon).  If an  Event  of  Default  of  the  type  described  in
     subparagraph  8(a)(vii)  above has  occurred,  then all of the  outstanding
     principal amount of the Debentures  shall  automatically be immediately due
     and  payable  without  any  action  on  the  part  of  any  Holders  of the
     Debentures.

               (ii) If an Event of  Default  has  occurred,  each  Holder of the
     Debentures  will also have any other  rights  which  such  Holder  may have
     pursuant  to  applicable  law,  in  each  case  provided  such  rights  are
     consistent with the provisions of paragraph 4 hereof.

     9. Amendment and Waiver. Except as otherwise expressly provided herein, the
provisions of this  Debenture may be amended and the Company may take any action
herein prohibited, or omit to perform any act herein required to be performed by
it,  only if the  Company  has  obtained  the  written  consent of the  Majority
Holders,  provided,  however,  neither the interest  rate or  principal  amounts
payable under the Debentures, the dates on which interest or principal under the
Debentures is due nor the  obligations  to make payments on the  Debentures on a
pro rata basis shall be amended without the prior written consent of each Holder
affected thereby,  and further provided,  however,  that any amendment or waiver
which might in any way adversely  affect the holders of Senior Debt,  including,
but not  limited  to,  any  amendment  or waiver  affecting  the  provisions  of
paragraph 4 or this paragraph 9  shall require the prior written consent of each
holder of Senior Debt. Any amendment or waiver  effected in accordance with this
paragraph 9  shall be binding upon each Holder of this Debenture and each future
Holder of this Debenture.

     10. Cancellation. After all principal and accrued interest at any time owed
on this  Debenture has been paid in full,  this Debenture will be surrendered to
the Company for cancellation and will not be reissued.

     11.  Place  of  Payment.  Payments  of  principal  and  interest  are to be
delivered to the Holder at the office of the Company, 50 Orville Drive, Bohemia,
New York  11716,  or to such  other  address or to the  attention  of such other
Person as specified by prior written notice to the Company.

     12. Waiver of Presentment,  Demand and Dishonor.  The Company hereby waives
presentment  for  payment,   protest,  demand,  notice  of  protest,  notice  of
non-payment  and  diligence  with  respect  to this  Debenture,  and  waives and
renounces  all  rights to the  benefit  of any  statute  of  

<PAGE>

limitations or any moratorium, appraisement, exemption or homestead now provided
or that  hereafter may be provided by any federal or applicable  state  statute,
including but not limited to exemptions provided by or allowed under the Federal
Bankruptcy  Code, both as to itself and as to all of its property,  whether real
or personal, against the enforcement and collection of the obligations evidenced
by this Debenture and any and all extensions, renewals and modifications hereof.

     No failure on the part of the Holder  hereof or of any other  Debentures to
exercise any right or remedy  hereunder  with  respect to the  Company,  whether
before or after the happening of an Event of Default,  shall constitute a waiver
of any future  Event of Default or of any other Event of Default.  No failure to
accelerate  the debt of the  Company  evidenced  hereby by reason of an Event of
Default  or  indulgence  granted  from time to time shall be  construed  to be a
waiver of the right to insist upon prompt payment thereafter; or shall be deemed
to be a novation of this  Debenture or a  reinstatement  of such debt  evidenced
hereby or a waiver of such  right of  acceleration  or any  other  right,  or be
construed  so as to  preclude  the  exercise  of any right the  Holder may have,
whether by the laws of the state  governing  this  Debenture,  by  agreement  or
otherwise; and the Company hereby expressly waives the benefit of any statute or
rule of law or equity  that would  produce a result  contrary  to or in conflict
with the foregoing.

<PAGE>

     13. Usury. The Holder and the Company intend that the obligations evidenced
by this Debenture  conform  strictly to the  applicable  usury laws from time to
time in force.  All agreements  between the Company and the Holder,  whether now
existing or hereafter arising and whether oral or written,  hereby are expressly
limited so that in no contingency or event  whatsoever,  whether by acceleration
of maturity  hereof or otherwise,  shall the amount paid or agreed to be paid to
the Holder,  or collected by the Holder,  by or on behalf of the Company for the
use, forbearance or detention of the money to be loaned to the Company hereunder
or otherwise,  or for the payment or  performance  of any covenant or obligation
contained  herein  of the  Company  to the  Holder,  or in  any  other  document
evidencing, securing or pertaining to such indebtedness evidenced hereby, exceed
the  maximum  amount  permissible  under  applicable  usury  law.  If under  any
circumstances  whatsoever  fulfillment  of any  provision  hereof  or any  other
document, at the time performance of such provisions shall be due, shall involve
transcending  the limit of validity  prescribed by law,  then,  ipso facto,  the
obligation to be fulfilled  shall be reduced to the limit of such validity;  and
if under any  circumstances  the Holder ever shall  receive from or on behalf of
the Company an amount deemed interest, by applicable law, which would exceed the
highest  lawful  rate,  such  amount  that  would be  excessive  interest  under
applicable  usury  laws  shall be  applied  to the  reduction  of the  Company's
principal amount owing hereunder and not to the payment of interest,  or if such
excessive  interest  exceeds  the  unpaid  balance of  principal  and such other
indebtedness,  the excess shall be deemed to have been a payment made by mistake
and shall be refunded to the Company or to any other person  making such payment
on the Company's behalf.

     14. Governing Law. The validity,  construction and  interpretation  of this
Debenture  will be governed by the internal  laws,  but not the law of conflicts
and choices of law, of the State of New York.

     IN WITNESS WHEREOF, the Company has executed and delivered this Amended and
Restated Class B 13% Convertible Senior Subordinated  Pay-in-Kind Debenture this
29th day of July, 1997.

                                             LOGIMETRICS, INC.



                                             By: _______________________________
                                                 Name:   Charles S. Brand
                                                 Title:  Chief Executive Officer
<PAGE>



                                    EXHIBIT A

                               ELECTION TO CONVERT


                  (All capitalized terms used and not otherwise
                     defined herein shall have the meanings
              assigned to them in the Amended and Restated Class B
           13% Convertible Senior Subordinated Pay-in-Kind Debentures)


LogiMetrics, Inc.
50 Orville Drive
Bohemia, New York  11716

TO WHOM IT MAY CONCERN:

     The undersigned registered owner of the attached Amended and Restated Class
B 13% Convertible Senior Subordinated  Pay-in-Kind  Debenture hereby irrevocably
exercises the option to convert such Debenture into Common Stock of LogiMetrics,
Inc. in accordance with the terms thereof,  and directs that any shares issuable
and  deliverable  upon the  conversion be issued in the name of and delivered to
the undersigned.



                        _________________________________
                            [Name of Debentureholder]



Dated:_______________ , 199_