EXHIBIT 10.3

                     NEGOTIABLE SECURED SENIOR SUBORDINATED
                                 PROMISSORY NOTE

$2,000,000                                                  Final Maturity Date:
                                                            December 31, 2000


          FOR VALUE RECEIVED,  LogiMetrics,  Inc., a Delaware  corporation  (the
"Maker"),  hereby promises to pay to the order of Signal Technology  Corporation
or its successors and assigns (the  "Holder"),  at its corporate  offices at 222
Rosewood Drive,  Danvers,  MA 01923, or at such other location as the Holder may
designate from time to time,  the aggregate  unpaid amount of all loans (each, a
"Loan") made by the holder to the Maker hereunder. Each Loan shall mature and be
due and payable,  together with all interest accrued thereon, in lawful money of
the United States of America on or before December 31, 2000,  or on demand under
certain circumstances as specified herein.

          The Maker promises to pay interest on the unpaid  principal  amount of
each  Loan  from the date  such Loan is made  until  its  maturity  (whether  by
acceleration  or otherwise),  at the rate of 10% per annum,  such interest to be
paid on maturity.

          1. If the Maker fails to pay any amount  hereunder when due,  interest
shall  thereafter  accrue on such overdue  amount at a rate of interest equal to
the lesser of:  (i) 18% per annum;  or (ii) the  highest  rate  permitted by law
until paid in full.  Interest  hereunder  shall be  calculated on the basis of a
360-day year for the actual number of days elapsed.

          2. The  maximum  aggregate  principal  amount  of the Loans to be made
hereunder  shall be  $2,000,000.  The Holder is  authorized  to record all Loans
evidenced  hereby  in its  records  (including,  but not  limited  to,  the grid
attached hereto as Schedule 1), and such entries shall be conclusive evidence of
amounts outstanding hereunder absent manifest error.

          3.  On  the  date  hereof,  the  Holder  is  advancing  to  the  Maker
$1,000,000.  The remaining  Loans hereunder shall be made in accordance with the
loan schedule set forth on Schedule II hereto.

          4. The Maker may prepay any Loan made  hereunder at any time, in whole
or in part, without premium or penalty. The Maker shall prepay all Loans in full
to the Maker within five (5) Business Days after:  (i) the  consummation  of any
public or private  offering by the Maker of its equity  securities or securities
convertible into or exchangeable for its equity securities pursuant to which the
Maker  receives  gross  proceeds  (before the  deduction  of offering  expenses,
discounts  and  commissions)  of at least Seven  Million Five  Hundred  Thousand
Dollars  ($7,500,000);  or (ii) the sale or transfer, in a single transaction or
in a series of related transactions,  of all or substantially all of the Maker's
assets,  or the merger,  consolidation,  reorganization  or  dissolution  of the
Maker,  or  the  sale,  in a  single  transaction  or  in a  series  of  related
transactions,  of a majority of the Maker's  voting capital stock (whether newly
issued or from  treasury,  or  previously  issued and then  outstanding,  or any
combination  thereof),  in each case other  than in a  transaction  with  Signal
contemplated  by the  Letter of Intent  (the  "Letter of  Intent")  of even date
herewith  between  Signal  and the  Company  (any of such  events,  a  "Disposal
Event"), or the execution by the Maker of any letter of intent or like agreement
with respect to the consummation of a Disposal Event. In addition,  in the event

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the  Maker  executes  a letter of intent or like  agreement  with  respect  to a
Disposal Event that is an Acquisition  Transaction  (as defined in the Letter of
Intent), or with respect to any other Acquisition Transaction, during the period
commencing  on such date as is 46 days  following  date of Letter of Intent  and
continuing  through and  including  such date as is 120 days  following  date of
Letter of Intent,  the Maker shall,  on the date it prepays all Loans in full in
accordance  herewith,  pay to the Holder a  prepayment  penalty in the amount of
$100,000.  As used herein,  "Business Day" means a day, other than a Saturday or
Sunday,  on which  commercial  banks in New York  City are open for the  general
transaction of business.

          5. At any time while Loans are outstanding hereunder, the Holder shall
have the right during normal  business hours to examine the books and records of
the Maker,  to make  copies,  notes,  and  abstracts  therefrom,  to discuss the
Maker's affairs with the officers,  directors, key employees, and accountants of
the Maker and, no more than once,  to make or cause an  independent  examination
and/or audit (at its expense) of the books and records of the Maker.

          6. The Maker shall pay to the Holder the  reasonable  attorneys'  fees
and  disbursements and all other  out-of-pocket  costs incurred by the Holder in
order to collect  amounts due and owing under this Note.  All payments  received
shall be applied, first, to the costs of collection, second, to unpaid interest,
and third, to principal.

          7. No delay or  failure on the part of the  Holder in  exercising  any
power,  right or remedy  hereunder  shall operate as a waiver of any such power,
right or remedy; nor shall any single or partial exercise of any power, right or
remedy preclude any other or further exercise of such power, right or remedy, or
the exercise of any other power, right or remedy, and no waiver whatsoever shall
be valid  unless in writing,  signed by the Holder,  and then only to the extent
expressly set forth therein.  No remedy is exclusive of any other remedy and all
remedies shall be cumulative to the maximum extent  permitted by applicable law.
The Maker hereby waives presentment,  demand for payment,  diligence,  notice of
dishonor  and all other  notices  or demands in  connection  with the  delivery,
acceptance, performance, default or endorsement of this Note.

          8. This Note is one of the Notes referred to in Amendment No. 2 to the
Second Amended and Restated Security Agreement,  Intercreditor Agreement, Waiver
and Consent,  dated the date hereof,  among the Maker, Cramer Rosenthal McGlynn,
LLC,  as Agent (the  "Agent"),  and the other  parties  thereto  (the  "Security
Agreement")  and is  secured  by the  Collateral  (as  defined  in the  Security
Agreement).  The Security Agreement grants the Agent on behalf of the Holder and
the other parties  thereto  certain rights with respect to the  Collateral  upon
certain defaults  specified therein and sets forth the related priorities of the
Holder and the other parties thereto with regard to such Collateral.

          9.  If  any  of  the  following  events  or  circumstances   (each  an
"Acceleration Event") shall occur:

          (a) the Maker shall fail to pay any amount of  principal,  interest or
other  amount (if any)  within ten (10) days of the date on which such amount is
due and payable hereunder; or

          (b) an Event of  Default  under  the  Security  Agreement  shall  have
occurred  and be  continuing  or the Maker  shall fail to cure any breach of its
other covenants,  agreements or obligations hereunder within ten (10) days after
written notice by the Holder to the Maker specifying such breach; or

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          (c) any  representation or warranty made by the Maker herein or in the
Security Agreement shall have been false in any material respect when made; or

          (d) the Maker shall make an  assignment  for the benefit of creditors,
or shall petition or apply for the appointment of a trustee or other  custodian,
liquidator or receiver of the Maker or of any substantial part of its assets, or
shall  commence  any case or other  proceeding  relating to its assets under any
bankruptcy,  reorganization,  arrangement,  insolvency,  readjustment  of  debt,
dissolution or liquidation or similar law of any jurisdiction, or shall take any
corporate action to authorize or in furtherance of any of the foregoing;  or any
such petition or application shall be filed or any such case or other proceeding
shall be commenced against the Maker, and the same shall not have been dismissed
within 60 days of the filing or commencement thereof or the Maker shall indicate
its approval thereof,  consent thereto or acquiescence  therein;  or a decree or
order shall be entered  appointing  any such trustee,  custodian,  liquidator or
receiver  or  adjudicating  the Maker  bankrupt  or  insolvent,  or  approving a
petition in any such case or other  proceeding,  or a decree or order for relief
shall be entered in respect of the Maker in an  involuntary  case under any such
bankruptcy or insolvency laws; or

          (e) the Maker shall take any corporate  action to liquidate its assets
or dissolve,  or shall take any corporate action to consolidate or merge with or
into any other  corporation  or  business  entity  unless the Maker shall be the
surviving  legal entity of such  consolidation  or merger or the surviving legal
entity of such  consolidation  or merger shall have assumed in full by a written
instrument  the  obligations  under and in respect of this Note,  other than any
such  corporate   action  in  connection  with  the   transaction   with  Signal
contemplated by the Letter of Intent; or

          (f) without the prior written  consent of the Holder,  the Maker shall
have  incurred  indebtedness  for borrowed  money (other than  indebtedness  for
borrowed  money,  together with interest  thereon,  existing on the date hereof)
which is or will be senior or pari passu to its indebtedness  hereunder,  except
for  indebtedness  incurred by the Maker pursuant to the Legacy Loan referred to
in the Loan  Agreement  of even date  herewith  between the Maker and the Holder
(the "Loan Agreement");

then, the Holder at its option at any time thereafter  during the continuance of
an Acceleration  Event may declare the entire and unpaid  principal of this Note
and all  interest,  fees and  expenses (if any) payable on or in respect of this
Note and the obligations  evidenced  hereby due and payable,  and the same shall
thereupon   forthwith   become  and  be  due  and  payable  to  the  Holder  (an
"Acceleration")  without presentment,  demand, protest, notice of protest or any
other formalities of any kind, all of which are hereby expressly and irrevocably
waived by the Maker,  provided that in the event of an Acceleration  Event under
Section 9(d) hereof all such amounts  shall  become and be  immediately  due and
payable, and  an  Acceleration  shall be deemed for all purposes  hereof to have
occurred, automatically and without any requirement of notice from the Holder.

          10.  The Maker  will not,  by  amendment  of its  Charter  or  through
reorganization, consolidation, merger, dissolution, issuance of capital stock or
sale of  treasury  stock  (otherwise  than upon  exercise of  conversion  rights
hereunder) or sale of assets,  or by any other  voluntary act or deed,  avoid or
seek to avoid the material  performance  or observance of any of the  covenants,
stipulations  or  conditions  in this Note to be  observed or  performed  by the

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Maker. The Maker will at all times in good faith assist,  insofar as it is able,
in the carrying out of all of the provisions of this Note in a reasonable manner
and in the taking of all other action which may be necessary in order to protect
and preserve the rights of the Holder set forth herein.

          11. This Note shall be binding upon the Maker and its  successors  and
assigns.  This Note shall be governed by, and construed in accordance  with, the
internal  laws of the  State of New York  pursuant  to  Section  15-1402  of the
General  Obligations  Law of such state.  The Maker  irrevocably  submits to the
exclusive  jurisdiction  of the  courts of the State of New York and the  United
States  District Court for the Southern  District of New York for the purpose of
any suit,  action,  proceeding  or  judgment  relating to or arising out of this
Note.  Service of process in connection with any such suit, action or proceeding
may be served on the Maker  anywhere  in the world by any method  authorized  by
law. The Maker irrevocably consents to the jurisdiction of any such court in any
such suit, action or proceeding.  The Maker irrevocably  waives any objection to
the  laying of venue of any such  suit,  action or  proceeding  brought  in such
courts and irrevocably waives any claim that any such suit, action or proceeding
brought in any such court has been brought in an inconvenient forum.

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          12.  No  modification,  alteration,  waiver  or  change  of any of the
provisions  hereof shall be effective  unless in writing and signed by the Maker
and the Holder and, then, only to the extent set forth in such writing.

ATTEST:                                     LOGIMETRICS, INC.



_____________________                               /s/Norman M. Phipps
Name:                                               ___________________________
                                             By:    Norman M. Phipps
                                                    Title:  President


Dated:  February 17, 2000

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                                   Schedule I




                                         Date of                 Notation
             Amount of Loan              Advance                  Made By
    ------------------------ ----------------------- ------------------------

    ------------------------ ----------------------- ------------------------
    ------------------------ ----------------------- ------------------------

    ------------------------ ----------------------- ------------------------
    ------------------------ ----------------------- ------------------------

    ------------------------ ----------------------- ------------------------
    ------------------------ ----------------------- ------------------------

    ------------------------ ----------------------- ------------------------
    ------------------------ ----------------------- ------------------------


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                                   Schedule II