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EXHIBIT 4.15

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933 AND MAY NOT BE OFFERED, SOLD OR OTHERWISE
TRANSFERRED IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT RELATIVE
THERETO UNDER THE SECURITIES ACT OF 1933 OR AN OPINION OF COUNSEL
REASONABLY SATISFACTORY TO THE COMPANY TO THE EFFECT THAT SUCH REGISTRATION
IS NOT REQUIRED UNDER THE ACT.

HALIFAX CORPORATION

7% Subordinated Debenture

FOR
VALUE RECEIVED, HALIFAX CORPORATION, a Virginia corporation (the
Company), hereby promises to pay to Research Industries Incorporated or
order on January 27, 2003, the principal sum of Two Million Dollars
($2,000,000.00), in lawful money of the United States, and to pay interest
on the unpaid principal amount from the date hereof until maturity at the
rate of seven percent (7%) per annum, in arrears, semiannually on or before
the first day of each six (6) month period beginning on August 1, 1998,
until maturity; and to pay interest on any overdue principal at the same
rate per annum payable monthly as aforesaid, or, at the option of the
holder hereof, on demand. Both payments of principal and of interest shall
be payable at the principal office of the payee. Each payment of interest
shall be made, without necessity of presentation hereof, by check drawn to
the order of the holder hereof and sent to such holder at the address
theretofor designated by such holder in writing.



| | 1. |  | SUBORDINATION
| | -- |  | -------------

The indebtedness evidenced by this Debenture is subordinated to the
prior payment in full of all indebtedness owing by the Company for money
borrowed from banks, insurance companies and other institutional lenders
and specifically to Crestar Bank in accordance with the terms and
conditions of a certain Subordination Agreement (Subordination Agreement)
dated January 27, 1998 by and among Research Industries Incorporated,
Crestar Bank and Halifax Corporation, a copy of which is attached hereto
and made a part hereof as Appendix A, and the terms of which are
incorporated by reference with the same force and effect as if set forth
herein.



| | 2. |  | CONVERSION
| | -- |  | ----------

2.1    At any time from the date of issuance up to
and including the date of maturity or of prepayment (as
permitted herein), the holder of this Debenture has the
right, at its option, to convert the then remaining
principal amount hereof, in part or in whole, into common
stock of the Company, as such stock shall be constituted at
the date of conversion (the Common Stock), at an initial
conversion price of ELEVEN and 72/100 DOLLARS ($11.72) (the
Conversion Price) of the remaining principal amount of
this Debenture for one (1) share of Common Stock, at the
office of the Company, accompanied by written notice of
election of conversion and accompanied by a written
instrument of transfer of the Debenture in form satisfactory
to the Company. No fractional shares or scrip representing
fractional shares will be issued upon any conversion, but an
adjustment in cash will be made in respect of any fraction
of a share which would otherwise be issuable upon the
surrender of any Debenture for conversion on the basis of
the then prevailing Conversion Price.

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2.2    Conversion shall be deemed to have been effected
on the date when delivery of the conversion notice,
accompanied by documents reasonably satisfactory to the
Company as provided in Section 2.1 above, is made (the
Conversion Date). As promptly as practicable thereafter, the
Company shall issue and deliver to or upon the written order
of such holder a certificate or certificates for the number of
full shares of Common Stock to which such holder is entitled
and a check or cash with respect to any fractional interest in
a share of Common Stock as provided below. The entity in whose
name the certificate or certificates for Common Stock are to
be issued shall be deemed to have become a shareholder of
record on the applicable Conversion Date unless the transfer
books of the Company are closed on that dale, in which event
it shall be deemed to have become a shareholder of record on
the next succeeding date on which the transfer books are open,
but the Conversion Price shall be that in effect on the
Conversion Date. Upon conversion of only a portion of this
Debenture, the Company shall issue and deliver to or upon the
written order of the holder hereof, at the expense of the
Company, a new Debenture covering the principal amount of this
Debenture not converted, which new Debenture shall entitle the
holder thereof to interest on the principal amount thereof to
the same extent as if the unconverted portion of this
Debenture had not been surrendered for conversion.



| | 3. |  | ADJUSTMENT OF CONVERSION PRICE
| | -- |  | ------------------------------

The Conversion Price (and as a result the number of shares
of Common Stock purchasable hereunder) shall be subject to
adjustment from time to time as follows:

3.1    In case the Company shall at any time or from
time to lime issue or sell any additional shares of its Common
Stock (other than not more than 280,000 shares issued upon
exercise of options granted by the Company to its employees and
directors) without consideration or for consideration per share
less than the Conversion Price in effect immediately prior to
the time of such issue or sale, then, forthwith upon such issue
or sale, said Conversion Price shall be adjusted to such lower
amount.

3.2    In case at any time the Company shall in any
manner issue or grant (a)
options to purchase or rights to subscribe for Common Stock,
(b) securities by their terms convertible into or exchangeable
for Common Stock, or (c) options to purchase or rights to
subscribe for such convertible or exchangeable securities (such
options, rights and convertible or exchangeable securities
being herein called Convertible Securities) and the price per
share for which Common Stock is issuable upon the exercise,
conversion or exchange of such Convertible Securities
(determined by dividing (x) the total amount, if any, received
or receivable by the Company as consideration for the granting
of such Convertible Securities, plus the minimum aggregate
amount of additional consideration, if any, payable upon the
exercise, conversion or exchange thereof, by (y) the total
maximum number of shares of Common Stock issuable upon the
exercise, conversion or exchange of such Convertible
Securities) shall be less than the Conversion Price in effect
immediately prior to the time of the granting of such rights or
options, then the Conversion Price shall be adjusted to such
lower amount upon the issue or grant of such Convertible
Securities; provided that no further adjustment of the
Conversion Price shall be made upon the actual issue of such
Common Stock upon the exercise, conversion or exchange of such
convertible Securities; and provided further, that upon the
expiration of such rights or options, if any thereof shall not
have been exercised, the Conversion Price shall forthwith be
readjusted and thereafter the Conversion Price shall be the
price which it would have been had adjustment been made on the
basis of the issue only of the shares of Common Stock actually
issued upon the exercise, conversion or exchange of such rights
or options.

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3.3    In case the Company shall at any time subdivide
its outstanding shares of Common Stock into a greater number
of shares, the Conversion Price in effect immediately prior to
such subdivision shall be proportionately reduced, and,
conversely, in case the outstanding shares of Common Stock of
the Company shall be combined into a smaller number of shares,
the Conversion Price in effect immediately prior to such
combination shall be proportionately increased.

3.4    In case the Company shall declare a dividend or make
any other distribution upon any stock of the Company payable in
Common Stock or in Convertible Securities, the aggregate maximum number of shares of
Common Stock issuable in payment of such dividend or distribution or upon conversion of or in
exchange for such Convertible
Securities issuable in payment of such dividend or
distribution, shall be deemed to have been
issued and the Conversion Price shall be decreased so that
the number of shares purchasable
hereunder shall be increased in proportion to such
increase in shares deemed to be outstanding.

3.5    If at any time while this Debenture is outstanding
there should be any
capital reorganization or reclassification of the capital
stock of the Company (other than a
subdivision or combination of shares provided for in
Section 3.3 hereof) or any consolidation or
merger of the Company with another corporation or any
sale, conveyance, lease or other transfer
by the Company of all or substantially all of its property
to any other corporation, the holder of
this Debenture shall thereafter upon exercise of this
Debenture be entitled to receive the number
of shares of stock or other securities or property of the
Company, or of the successor corporation
resulting from such consolidation or merger, as the case
may be, to which the Common Stock
(and any other securities and property) of the Company,
deliverable upon the conversion of this
Debenture would have been entitled upon such capital
reorganization, reclassification of capital
stock, consolidation, merger, sale or other transfer if
this Debenture had been converted
immediately prior to such capital reorganization,
reclassification of capital stock, consolidation,
merger, sale or other transfer; and, in any such case,
appropriate adjustment (as reasonably
determined by the Board of Directors of the Company) shall
be made in the application of the
provisions herein set forth with respect to the rights and
interests thereafter of the holder of this
Debenture to the end that the provisions set forth herein
(including the adjustment of the
Conversion Price and the number of shares issuable upon
the conversion of this Debenture) shall
thereafter be applicable, as near as reasonably may be, in
relation to any shares or other property
thereafter deliverable upon the conversion hereof as if
this Debenture had been exercised
immediately prior to such capital reorganization,
reclassification of capital stock, consolidation,
merger, sale or other transfer and the holder hereof had
carried out the terms of the exchange as
provided for by such capital reorganization,
reclassification of capital stock, consolidation or
merger. In the event that in any capital reorganization or
reclassification, consolidation or
merger, additional shares of Common Stock shall be issued
in exchange, conversion, substitution
or payment, in whole or in part for or on account of a
security of the Company other than
Common Stock, any such issue shall be treated as an issue
of Common Stock covered by the
provisions of Section 3 above with the amount of the
consideration received upon the issue
thereof being reasonably determined by the Board of
Directors of the Company. The Company
shall not effect any such capital reorganization,
consolidation or merger unless, upon or prior to
the consummation thereof, the successor corporation shall
assume by written instrument the
obligation to deliver to the holder hereof such shares of
stock, securities, cash or property as such
holder shall be entitled to purchase in accordance with
the foregoing provisions.

3.6    In case at any time the Company shall propose to
take any action requiring an adjustment of the Conversion Price,
then, in any of said cases, the Company shall give prior

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written notice, by first-class mail, postage prepaid,
addressed to the holder of this Debenture at the address of
such holder as shown on the books of the Company, of the date
on which (a) the books of the Company shall close or a record
shall be taken for such action or (b) such action shall take
place, as the case may be. Such notice shall also specify the
date as of which the holders of the Common Stock of record
shall participate in said action. Such written notice shall
be given at least 20 days prior to the action in question and
not less than 20 days prior to the record dale or the date on
which the Companys transfer books are closed in respect
thereto.

3.7    For the purpose of any adjustment of the
Conversion Price pursuant to Section 3 hereof, the following
provisions shall also be applicable:



| |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
| | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | 3.7.1    In case any shares of Common Stock or
Convertible Securities shall be issued for cash, the
consideration received therefor shall be deemed to be
the amount received by the Company therefor after
deducting therefrom any expenses incurred and any
underwriting commissions or concessions paid or allowed
by the Company in connection therewith. In case any
shares of Common Stock or Convertible Securities shall be
issued for a consideration other than cash (or a
consideration which includes cash, if such cash
constitutes a part of the assets of a corporation or
business substantially all of the assets of which are
being received as such consideration), then, for the
purposes of this Section 3, the Board of Directors shall
reasonably determine the fair value of such
consideration, and such Common Stock or Convertible
Securities shall be deemed to have been issued for an
amount of cash equal to the value so determined by the
Board of Directors. In case any shares of Common Stock or
Convertible Securities shall be issued together with
other stock or securities or other assets of the Company
for a consideration which includes both, the Board of
Directors shall similarly determine what part of the
consideration so received is to be deemed to be
consideration for the issue of such shares of such Common
Stock or Convertible Securities.
|
| | 3.7.2    So long as this Debenture remains
outstanding, the Company will not
issue any additional capital stock of any class
preferred as to dividends or as to the
distribution of assets upon voluntary or
involuntary liquidation, dissolution or
winding up, unless the rights of the holders
thereof shall be limited to a fixed sum or
percentage of par value in respect of
participation in dividends and in the distribution
of such assets.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|
| | 3.7.3    All calculations under this Section 3
shall be made to the nearest cent
or to the nearest one hundredth (l/100th) of a share, as the case may be.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
|
| | 3.7.4    Anything in this Section 3 to the contrary notwithstanding, the
Company shall not be required to give effect to any
adjustment in the Conversion
Price unless and until the net effect of one or more
adjustments, determined as above
provided, shall have resulted in a change of the
Conversion Price by at least $0.05 per
share, such change in the actual conversion price
shall thereupon be given effect.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
|
| | 3.7.5    Upon any adjustment to the Conversion
Price and/or an increase or
decrease in the number of shares of Common Stock
purchasable upon the exercise of
the conversion right set forth in this
Debenture, then, and in each such case, the
Company, within 10 days thereafter, shall give
notice thereof to the holder of this
Debenture stating the adjusted Conversion Price
and the increased or decreased
number of shares purchasable upon such exercise
and setting forth in reasonable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      

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| |                                                                                                                                                                                                                                                                                                                                                                                                       
| | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | detail the method of calculation and the facts (including
a statement of the consideration received or deemed to
have been received by the Company for any shares of Common
Stock or of Convertible Securities) upon which such
calculation is based. Where appropriate, such notice may
be given in advance and included as a part of the notice
required to be given pursuant to Section 3.6 hereof.



| | 4. |  | RESERVATION OF SHARES; SHARES TO BE FULLY PAID;
COMPLIANCE WITH GOVERNMENTAL REQUIREMENTS; LISTING OF
COMMON STOCK
| | -- |  | ------------------------------------------------------------------------------------------------------------------

The Company shall provide, free from preemptive rights,
out of its authorized but unissued shares, or out of shares
held in its treasury, sufficient shares to provide for the
conversion of the Debentures from time to time as such
Debentures are presented for conversion.

4.1    The Company covenants that all shares of Common Stock
which may be
issued upon conversion of Debentures will upon issue be
fully paid and nonassessable by the
Company and free from all taxes, liens and charges with
respect to the issue thereof.

4.2    The Company covenants that if any shares of Common
Stock to be
provided for the purpose of conversion of Debentures
hereunder require registration with or
approval of any governmental authority under any Federal
or state law before such shares may be
publicly traded following conversion, the Company will in
good faith and as expeditiously as
possible endeavor to secure such registration or approval,
as the case may be.

4.3    The Company further covenants that so long as the
Common Stock shall
be listed on the American Stock Exchange or in the event
that it becomes listed or, any other
national securities exchange the Company will, if
permitted by the rules of such exchange, list
and keep listed and for sale so long as the Common Stock
shall be so listed on such exchange,
upon official notice of issuance, all Common Stock
issuable upon conversion of the Debentures.



| | 5. |  | PREPAYMENT OF DEBENTURES
| | -- |  | ------------------------

Subject to the terms and conditions hereof and the
Subordination Agreement, this Debenture may be prepaid, as a
whole or in part or parts, on any date more than two (2) years
after the date hereof as specified in a notice of prepayment, by
payment of all or a portion of the principal amount together
with interest on such principal amount accrued to the date fixed
for prepayment. If the Company shall determine to prepay all or
a portion of this Debenture, it shall cause written notice
thereof to be given by registered or certified mail, postage
prepaid, to the holder of this Debenture at least 60 days prior
to the date fixed for such prepayment. Such notice shall state
the prepayment date and the amount to be prepaid. The holder of
this Debenture may subsequently convert this Debenture, in whole
or in part, at any time prior to the prepayment date.



| | 6. |  | AFFIRMATIVE COVENANTS OF THE COMPANY
| | -- |  | ------------------------------------

Unless otherwise consented to in writing by the holder
of this Debenture, the Company covenants that it will:

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6.1    Maintain its corporate existence and (he
corporate existence of its subsidiaries, if any, and make
every reasonable effort to comply and cause its subsidiaries
to comply in such manner as advised so to do by its counsel
with all laws, governmental regulations, rules and ordinances,
and judicial orders, judgments and decrees applicable to the
Company, its subsidiaries, their business or their property
(except while the Company or a subsidiary is in good faith and
by appropriate proceedings contesting the validity of any of
the foregoing); keep adequate books of account in accordance
with generally accepted accounting principles consistently
maintained (except as the Company or a subsidiary shall decide
to make any change in accounting methods or practices which is
consistent with generally accepted accounting principles); and
maintain and operate its properties and those of its
subsidiaries in a manner consistent with the efficient
operation of the business of the Company and its subsidiaries;

6.2    Punctually pay and discharge or cause to be paid and
discharged all taxes,
assessments, and governmental charges lawfully imposed
upon it or any subsidiary or any of
their property, or upon the income and profits thereof;
provided, however, that nothing herein
contained shall require it or a subsidiary to pay or
discharge any tax, assessment, or
governmental charge, so long as the validity thereof shall
be contested by it in good faith and by
appropriate proceedings and, if necessary, there shall
have been established on the appropriate
books a reserve therefor deemed adequate by its Board of
Directors, unless thereby property
essential to the conduct of business will be lost,
forfeited, or materially endangered;

6.3    At all times maintain, preserve, and keep its
properties and those of its
subsidiaries and each and every part and parcel thereof in
good repair, working order, and
condition so that the business carried on in connection
therewith may be properly and
advantageously conducted, but nothing herein contained
shall be construed to prevent the
Company or a subsidiary from surrendering or
discontinuing, or abandoning or selling, or
disposing of any property, in whole or in part, which is
deemed by its Board of Directors to be no
longer useful or of productive value to it, or where such
surrender, discontinuance, abandonment,
sale, or other disposition is deemed by its Board of
Directors to be advantageous in the due and
proper conduct of its business; and

6.4    Maintain, for itself and cause each subsidiary to maintain property and
liability insurance with reputable insurance companies
insuring against such risks and in such
amounts as are appropriate considering the size and the
business of the Company and each
subsidiary.

6.5    At all times have authorized, and reserved for the purpose of issue upon
conversion of this Debenture, a sufficient number of
shares of its common Stock to provide for
the exercise of the conversion rights granted pursuant
hereto.



| | 7. |  | ACTS OF DEFAULT
| | -- |  | ---------------

The following shall be deemed acts of default:

7.1    Default in the payment of any installment of interest
when it becomes due
and payable; or

7.2    Default in the payment of the principal at maturity or
upon prepayment of
all or a portion thereof on the date fixed for such
prepayment; or

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7.3    Breach of or default in the performance of any
covenants herein and
continuance of such breach or default for a period of 30
days after notice to the Company by the
holder hereof, or

7.4    Breach of or default in any of the terms of borrowings by the Company
constituting Superior Indebtedness unless waived in
writing by the holder of such Superior
Indebtedness within the period provided in such
indebtedness but in no event to exceed 30 days;
or

7.5    Any insolvency or bankruptcy proceeding commenced by or against the
Company unless stayed or dismissed within 30 days.



| | 8. |  | CONSEQUENCES OF DEFAULT
| | -- |  | -----------------------

If any act of default occurs, the principal and interest
due hereunder shall be due and payable immediately without
presentment for payment, protest, or notice of nonpayment. If
the principal and interest hereon is not paid when due, the
holder hereof may resort to such process, legal or equitable,
as is necessary to collect the same, subject to the provisions
of the Subordination Agreement. In the event this Debenture
shall be referred to an attorney for collection, the Company
agrees to pay all reasonable costs of collection, including a
reasonable sum for attorneys fees. In the event this
Debenture shall become due and payable by an act of default
hereunder, holder shall have the additional option of
converting the total amount of principal and interest due
hereunder into common shares of the Company in the manner and
for the price provided for hereinabove. The Company shall
forthwith upon obtaining knowledge notify the holder of the
Debenture of the occurrence of any event or circumstance
(without taking into account any grace period) which gives or
will give rise to an act of default.



| | 9. |  | TRANSFERABILITY
| | -- |  | ---------------

Subject to the terms of the legend hereon, this Debenture
may be transferred or endorsed to another by giving notice
thereof to the Company at its principal office or, if a new
Debenture is requested in connection with such transfer, by
surrender thereof for cancellation, endorsed or accompanied by
a written instrument of transfer, in form satisfactory to the
Company, duly executed by the holder thereof in person or by
his duly authorized representative, or by his agent or
attorney duly appointed in writing, and thereupon the Company
will issue and deliver, in the name of the transferee or
transferees, a new Debenture, of like terms and for a like
aggregate principal amount, expressly subject to the
Subordination Agreement, dated so that no gain or loss of
interest shall result from such transfer.



| | 10. |  | DAMAGED OR MISSING DEBENTURES
| | --- |  | -----------------------------

If there be delivered to the Company evidence to its
reasonable satisfaction of the destruction, loss, theft or
mutilation of the Debenture and if the holder shall provide
such indemnity that may be required to save the Company and the
holder harmless, then in the absence of notice to the Company
that such Debenture has been acquired by a bona fide purchaser,
the Company shall execute and deliver to holder, in lieu of or
in exchange for such Debenture, a new Debenture of like terms
and principal amount, expressly subject to the Subordination
Agreement, and such Debenture shall be entitled to all the
rights and benefits of the original Debenture.

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| | 11. |  | NOTICE
| | --- |  | ------

Any notice, payment or delivery required or desired
hereunder shall be effective when mailed by first-class mail,
postage prepaid, addressed to the Company at 5250 Cherokee
Avenue, Alexandria, Virginia 22312 or to Research Industries
Incorporated the original holder, 123 North Pitt Street,
Alexandria, Virginia 22314 or at such other address as may be
provided by the holder hereof in writing.

IN WITNESS WHEREOF, HALIFAX CORPORATION, has caused this
Debenture to be signed in its corporate name and its corporate
seal to be impressed hereon by its duly authorized officers.

Dated: January 27, 1998

| |                     |                
| | ------------------- | ---------------
| | HALIFAX CORPORATION
| |                     |                
| | By                  | /s/ H. C. Mills
| |                     |                
| |                     | President      

|        |  |       
|------- |  | ------
|        |  | (SEAL)
|Attest: |  |       

|                                     
|-------------------------------------
|/s/ Ernest L. Ruffner                
|                                     
|Ernest L. Ruffner
Corporate Secretary

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