Exhibit 1

NO. _______                                                         $___________


                             NAI TECHNOLOGIES, INC.

                                   FORM OF

                  12% CONVERTIBLE SUBORDINATED PROMISSORY NOTE

                         MATURITY DATE: JANUARY 15, 2001

THIS NOTE AND THE COMMON  STOCK THAT MAY BE ISSUABLE  TO THE HOLDER  HEREOF HAVE
NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE
SOLD, PLEDGED, HYPOTHECATED, DONATED OR OTHERWISE TRANSFERRED WITHOUT COMPLIANCE
WITH THE  REGISTRATION  OR  QUALIFICATION  PROVISIONS OF APPLICABLE  FEDERAL AND
STATE SECURITIES LAWS OR APPLICABLE EXEMPTIONS THEREFROM.

         FOR VALUE RECEIVED, NAI TECHNOLOGIES, INC., a New York corporation (the
"Company"), promises to pay to ______________________,  the registered holder or
registered   assigns   hereof   (the   "Holder"),   the   principal   amount  of
_________________  Dollars  ($_________) payable on the fifteenth day of January
2001 (the "Maturity Date"),  together with interest on the outstanding principal
amount of this Note at the rate of twelve percent (12%) per annum  calculated on
the basis of a 360 day  year,  such  interest  to be  payable  in  arrears  on a
quarterly basis on the fifteenth day of January, April, July and October of each
year,  commencing  on April 15,  1996.  In the  event  that any  payment  of any
principal and/or interest hereunder is not paid when due as provided for herein,
and without affecting any of the Holder's other rights and remedies,  the unpaid
principal  balance hereof shall thereafter accrue interest at the defaulted rate
specified in Section 11(a) of this Note.

         This  Note  is  one  of a  series  of  the  Company's  12%  Convertible
Subordinated  Promissory Notes (collectively,  the "Notes"),  issued pursuant to
that certain Confidential Private Placement Memorandum, dated December 15, 1995,
as supplemented  (the  "Memorandum").  Capitalized  terms used and not otherwise
defined herein shall have the respective  meanings attributed thereto in Section
13.

         1. Payments and Prepayments.

         (a)  Payments of  principal  and interest on this Note shall be made at
the  principal  office of the  Company,  located  at 2405 Trade  Centre  Avenue,
Longmont, Colorado 80503, or such other place or places within the United States
as may be  specified  by the  Holder  of this  Note in a  written  notice to the
Company at least ten (10) business days before a given payment date.







         (b)  Payments of  principal  and interest on this Note shall be made in
lawful money of the United States of America by mailing the Company's good check
in the proper  amount to the Holder at least three days prior to the due date of
each payment or otherwise  transferring funds so as to be received by the Holder
on the due date of each such payment; provided, however, that, in the event that
the principal amount of this Note is at least $1,000,000, the Company shall make
payment by wire transfer to an account such Holder may specify in writing to the
Company at least three days prior to the due date of each payment.

         (c) If any payment on this Note  becomes due and payable on a Saturday,
Sunday  or  other  day on  which  commercial  banks  in New  York,  New York are
authorized or required by law to close,  the maturity  thereof shall be extended
to the next succeeding  business day and, with respect to payments of principal,
interest  thereon shall be payable during such extension at the then  applicable
rate.

         (d) Subject to the  provisions  of Section 4 and 5 below,  this Note is
subject to  prepayment,  in whole but not in part, at the option of the Company,
at any time after the third  anniversary of the date hereof,  without premium or
penalty.  In the event of any partial payment of principal or accrued  interest,
for whatever reason, or prepayment, any such partial payment of principal and/or
interest or  prepayment  of principal on the Notes shall be allocated  among the
respective Notes and holders thereof so that the amount of such payments to each
holder  shall  bear as nearly as  practicable  the same  ratio to the  aggregate
amount  then to be paid as the  principal  amount of the Notes then held by such
holder bears to the aggregate principal amount of Notes then outstanding.

         (e) The Company  will give the Holder  written  notice  indicating  the
amount of any  prepayment and the proposed date thereof not more than sixty (60)
days and not less than  thirty  (30) days prior to any such  prepayment  of this
Note.

         (f) Subject to the  provisions  of Sections 4 and 5 below,  the Company
shall, within thirty (30) business days of the occurrence of a Change in Control
(as defined in Section 13  hereof),  offer,  by written  notice to the Holder in
accordance  with Section  1(e),  to prepay this Note,  in whole and not in part,
without premium or penalty.  Holder may accept the offer to prepay made pursuant
to this Section 1(f) by causing notice of such acceptance to be delivered to the
Company at least ten (10) days prior to the  proposed  prepayment  date (or such
longer  period as may be required by law).  A failure by Holder to respond to an
offer to prepay  pursuant to this Section 1(f) within the requisite  time period
shall be deemed to constitute a rejection of such offer.

         2. Obligation  Absolute.  The obligations  under this Note are absolute
and  unconditional  obligations  of the  Company and no  modification,  release,
consent, waiver,  rearrangement or amendment shall impair the obligations of the
Company hereunder.

                                        2







         3.  Security.  The payment of this Note and the  Company's  obligations
hereunder,  and under the Warrant and the Registration Rights Agreement (as such
terms are defined in the Memorandum) are not secured by any collateral.

         4.  Subordination.  (a) The  Company  for itself,  its  successors  and
assigns,  covenants and agrees, and each Holder of this Note, its successors and
assigns,  by its acceptance of this Note likewise covenants and agrees,  that to
the extent  provided  below the payment of the principal of and interest on this
Note is hereby  expressly  subordinated  and junior in right of payment,  to the
extent and in the manner  hereinafter set forth, to all Senior  Indebtedness (as
hereinafter defined). For purposes hereof, Senior Indebtedness is defined as:

                           (i)  the  principal  of,  premium,  if  any,  and any
                  interest  (including,  without  limitation,  any  interest  on
                  interest  and  post-bankruptcy   petition  interest)  on,  all
                  liabilities of the Company (including, without limitation, all
                  liabilities  of the  Company  with  respect  to any  costs and
                  expenses),   direct   or   contingent,   joint,   several   or
                  independent,  now or hereafter existing, due or to become due,
                  whether   created   directly  or  acquired  by  assignment  or
                  otherwise,  under or in respect of that  certain  Amended  and
                  Restated Credit  Agreement,  dated as of April 12, 1995, among
                  the Company, The Bank of New York, Chemical Bank and the other
                  parties  referred to therein (as  heretofore  and as hereafter
                  amended,  modified  and  supplemented  from time to time,  the
                  "Bank Credit  Agreement")  and any of the other Loan Documents
                  (as defined in the Bank Credit Agreement); and

                           (ii) all  extensions,  renewals and refundings of any
                  of the  foregoing  (provided  that  the  amount  of  any  debt
                  incurred  in  connection  with  such  extension,   renewal  or
                  refunding  does  not  exceed  the  amount  of the  outstanding
                  obligations of the Company under the Bank Credit  Agreement at
                  the time of the extension,  renewal or refunding  (whether for
                  interest,  principal  or fees,  or  expenses  incurred  by the
                  holders  of  Senior   Indebtedness   for  the   protection  of
                  collateral and reasonable costs of collection));

provided,  however,  that the term "Senior  Indebtedness"  shall not include any
indebtedness  expressly subordinated in writing to the Notes or any indebtedness
owed to affiliates of the Company.

         (b)  Upon  the  acceleration  of any  Senior  Indebtedness  or upon the
maturity of the entire principal  amount of any Senior  Indebtedness by lapse of
time, acceleration or otherwise,  all such Senior Indebtedness which has been so
accelerated  or matured  shall  first  indefeasibly  be paid in full  before any
payment is made by the Company or any person  acting on behalf of the Company on
account of any obligations evidenced by this Note.

         (c)  Notwithstanding  anything to the contrary  contained  herein,  the
Company  shall  not (i) pay any  principal  portion  of this Note so long as any
Senior  Indebtedness  remains outstanding or (ii) pay any interest payable under
this Note if there exists a Default or

                                        3







Event of Default (as such terms are defined in the instruments evidencing Senior
Indebtedness) with respect to any Senior Indebtedness  (hereinafter  referred to
as a "Blockage Event").

                  The Company  shall resume  payment of interest  payable  under
this Note and a Blockage Event shall be deemed to have terminated:

                    (i)  when  such  Default  or  Event  of  Default  on  Senior
               Indebtedness, as applicable, is cured or waived;

                    (ii)  when the  Holder  hereof  shall  have  cured  any such
               Default or Event of Default on Senior  Indebtedness to the extent
               such  Default  or Event of  Default  can be cured by  payment  of
               money,  which amount shall be added to the principal amount owing
               to the Holder pursuant to this Note; or

                    (iii) 180 days after the occurrence of such Default or Event
               of Default, provided, that at the end of such 180 days, if any of
               the following  events exists or occurs,  the Blockage Event shall
               continue:  (A) a Default in payment of any amount with respect to
               the  Senior  Indebtedness;  (B) an  acceleration  of  the  Senior
               Indebtedness;  or (C) the  occurrence  of an  event  of the  type
               described in Section 5 hereof, provided, further, that a Blockage
               Event  with  respect  to a single  specified  Default or Event of
               Default may be deemed to occur only once for each 360 day period.

         (d) At any time there exists a Blockage  Event,  (i) the Company  shall
not, directly or indirectly, make any payment of any part of this Note, (ii) the
Holder  hereof  shall not demand or accept from the Company or any other  person
any such  payment or  cancel,  set-off or  otherwise  discharge  any part of the
indebtedness  represented  by this Note,  and (iii)  neither the Company nor the
Holder  hereof  shall  otherwise  take or permit  any action  prejudicial  to or
inconsistent  with the  priority  position of any holder of Senior  Indebtedness
over the  Holder  of this  Note.  Notwithstanding  the  foregoing  or any  other
provision of this Note to the contrary,  the  occurrence  and  continuance  of a
Blockage Event shall not limit or in any other manner affect the exercise of the
Holder's conversion rights pursuant to Section 6.

         (e) Any holder of Senior  Indebtedness  is hereby  authorized to demand
specific  performance  of this  Note,  whether  or not the  Company  shall  have
complied  with the  provisions  hereof  applicable  to it,  at any time when the
Holder hereof shall have failed to comply with any provision  hereof  applicable
to such Holder.  The Holder hereby  irrevocably  waives any defense based on the
adequacy  of a remedy at law which  might be  asserted as a bar to the remedy of
specific  performance  hereof in any action  brought  therefor  by any holder of
Senior Indebtedness.  The Holder further (i) waives presentment,  demand, notice
and protest in connection  with all  negotiable  instruments  evidencing  Senior
Indebtedness,  notice of any loan made,  extension granted or other action taken
in reliance  hereon and all demands and notices of every kind in connection with
this Note or Senior Indebtedness;  and (ii) assents to any renewal, extension or
postponement of the time of payment of Senior Indebtedness or any other

                                        4







indulgence with respect  thereto,  to any  substitution,  exchange or release of
collateral  therefor and to the  addition or release of any person  primarily or
secondarily liable thereon.

         (f) The Company and the Holder shall  execute and deliver to any holder
of Senior  Indebtedness  such  further  instruments  and shall take such further
action as such holder of Senior Indebtedness may at any time or times reasonably
request in order to evidence the subordination of the obligations  hereunder and
to otherwise carry out the provisions and intent of this Note.

         (g) No right of any  holder  of  Senior  Indebtedness  to  enforce  the
subordination of the obligations  shall be impaired by any act or failure to act
by the Company or the Holder or by their failure to comply with this Note or any
other agreement or document  evidencing,  related to or securing the obligations
hereunder. Without in any way limiting the generality of the preceding sentence,
the  holders  of  Senior  Indebtedness  may,  at any time and from time to time,
without the consent of or notice to the Holder, without incurring responsibility
to the Holder and without impairing or releasing the  subordination  provided in
this Note or the  obligations  of the  Holder  hereof to the  holders  of Senior
Indebtedness,  do any one or more of the following: (i) change the manner, place
or terms of payment of, or renew or alter, any Senior Indebtedness, or otherwise
amend or supplement in any manner, any Senior  Indebtedness,  or otherwise amend
or  supplement  in  any  manner,  any  Senior  Indebtedness  or  any  instrument
evidencing  the  same  or any  agreement  under  which  Senior  Indebtedness  is
outstanding;  (ii) sell,  exchange,  release or otherwise deal with any property
pledged, mortgaged or otherwise securing any Senior Indebtedness;  (iii) release
any  Person or entity  liable in any  manner  for the  collection  of any Senior
Indebtedness;  and (iv) exercise or refrain from  exercising  any rights against
the Company or any other Person or entity.

         (h) In the event that the Company  shall make any payment or prepayment
to the Holder on account of the obligations  under this Note which is prohibited
by this  Section 4, such payment  shall be held by the Holder,  in trust for the
benefit of, and shall be paid  forthwith  over and  delivered to, the holders of
Senior  Indebtedness  (pro rata as to each of such  holders  on the basis of the
respective  amounts and priorities of Senior  Indebtedness  held by them) to the
extent  necessary to pay all Senior  Indebtedness  due to such holders of Senior
Indebtedness  in full in accordance  with its terms  (whether or not such Senior
Indebtedness is due and owing), after giving effect to any concurrent payment or
distribution to or for the holders of such Senior Indebtedness.

         (i)  After all  Senior  Indebtedness  indefeasibly  is paid in full and
until the  obligations  under this Note are paid in full,  the  Holder  shall be
subrogated  to the rights of holders of Senior  Indebtedness  to the extent that
distributions  otherwise  payable to the Holder have been applied to the payment
of Senior  Indebtedness.  For  purposes  of such  subrogation,  no  payments  or
distributions  to holders of such Senior  Indebtedness of any cash,  property or
securities  to which the Holder would be entitled  except for the  provisions of
this Section 4 and no payment over pursuant to the  provisions of this Section 4
to holders of such  Senior  Indebtedness  by the Holder,  shall,  as between the
Company, its creditors, other than holders of

                                        5







such  Senior  Indebtedness,  and the  Holder,  be deemed to be a payment  by the
Company to or on account of such Senior  Indebtedness,  it being understood that
the  provisions  of this  Section 4 are solely for the purpose of  defining  the
relative rights of the holders of such Senior Indebtedness, on the one hand, and
the Holder hereof, on the other hand.

         5. Primacy of Senior  Indebtedness Claims as Against the Holder. In any
insolvency, receivership, bankruptcy, dissolution, liquidation or reorganization
proceeding, or in any other proceeding,  whether voluntary or involuntary, by or
against the Company under any  bankruptcy or insolvency  law or laws relating to
relief of debtors, to compositions, extensions or readjustments of indebtedness:

          (a) the  claims of any  holders  of Senior  Indebtedness  against  the
     Company  shall be paid  indefeasibly  in full in cash before any payment is
     made to the Holder;

          (b) until all Senior Indebtedness is indefeasibly paid in full in cash
     any distribution to which the Holder would be entitled but for this Section
     5 shall be made to holders of Senior Indebtedness; and

          (c) the  holders  of  Senior  Indebtedness  shall  have  the  right to
     enforce,  collect and receive every such payment or  distribution  and give
     acquittance  therefor.  In furtherance of the foregoing,  in the event that
     the  Company  shall  file or have filed  against  it a  petition  under any
     chapter of Title 11 of the United  States Code or any  comparable  statute,
     with the result that the Company is excused from the  obligation to pay all
     or any part of the  amount  otherwise  payable  in  respect  of the  Senior
     Indebtedness  during  the period  subsequent  to the  commencement  of such
     proceedings,  the Holder  agrees that all or such part of such amount shall
     be payable  out of, and to that extent  diminish  and be at the expense of,
     the Holder's reorganization  dividends or other distributions in respect of
     any claim filed by it as a creditor or  interest  holder.  In the event the
     holders of Senior Indebtedness receive amounts in excess of payment in full
     (in cash) of amounts outstanding in respect of Senior Indebtedness (without
     giving effect to whether claims in respect of the Senior  Indebtedness  are
     allowed  in  any  insolvency   proceeding),   the  holders  of  the  Senior
     Indebtedness shall pay such excess amounts to the Holder.

         6. Conversion. The Holder of this Note will have the right, exercisable
at any time on or before  the  Maturity  Date,  by notice to the  Company at its
principal  office,  at the Holder's option, to convert the then unpaid principal
amount of this Note (or any  portion  hereof  that is an  integral  multiple  of
$1,000) into 500 fully paid and non-assessable shares of common stock, par value
$.10 per share,  of the Company (the "Common Stock") for each $1,000 face amount
of this Note,  representing a conversion price equal to $2.00 per share, subject
to adjustment as set forth below (the  "Conversion  Price").  The Company may at
any time,  by notice  to the  Holder,  require  the  conversion  of this Note in
accordance  with this Section 6, and the Holder shall  promptly  surrender  this
Note for conversion  following such notice,  provided that the Closing Price for
the Common Stock for thirty (30)  consecutive  trading days prior to such notice
is equal to or greater than $6.00 per share.

                                        6








         Subject to the right of the Holder on the date of conversion to receive
all interest on such Note accrued through such date of conversion, no adjustment
for  interest or dividends  will be made upon the  conversion  of this Note.  No
fractional shares will be issued upon conversion,  but if the conversion results
in a fraction,  the fair market value of such  fractional  share of Common Stock
(which  shall be the closing  price of such shares on the  exchange or market on
which the Common Stock is then traded) will be paid by the Company in cash. This
right of  conversion  shall  cease  upon  payment in full of all  principal  and
interest  and other  amounts due in respect of this Note.  Nothing  contained in
this  paragraph  shall  authorize the payment of interest to the Holder when the
terms of this Note otherwise prohibit the same.

         The  occurrence  of  any of  the  following  events  shall  trigger  an
adjustment from time to time to the Conversion Price and the number of shares of
Common Stock into which this Note shall be converted (the "Conversion Shares"):

          (a)   Recapitalization,   Reclassification  and  Succession.   If  any
     recapitalization  of the Company or reclassification of its Common Stock or
     any merger or  consolidation  of the Company into or with a corporation  or
     other business entity,  or the sale or transfer of all or substantially all
     of the  Company's  assets or of any successor  corporation's  assets to any
     other  corporation  or  business  entity  (any  such  corporation  or other
     business  entity being included  within the meaning of the term  "successor
     corporation")  shall be  effected,  at any time  while  this  Note  remains
     outstanding,    then,   as   a   condition   of   such    recapitalization,
     reclassification,  merger,  consolidation,  sale or  transfer,  lawful  and
     adequate provision shall be made whereby the Holder of this Note thereafter
     shall have the right to receive upon the  conversion  hereof as provided in
     this  Section  6 and in lieu of the  shares  of  Common  Stock  immediately
     theretofore  issuable  upon the  conversion  of this Note,  such  shares of
     capital  stock,  securities  or other  property as may be issued or payable
     with respect to or in exchange for a number of outstanding shares of Common
     Stock equal to the number of shares of Common Stock immediately theretofore
     issuable  upon the  conversion  of this  Note  had  such  recapitalization,
     reclassification,  merger, consolidation, sale or transfer not taken place,
     and in each such case,  the terms of this Note shall be  applicable  to the
     shares  of  stock or  other  securities  or  property  receivable  upon the
     conversion of this Note after such consummation.

          (b)  Subdivision or Combination of Shares.  If the Company at any time
     while this Note remains  outstanding  shall subdivide or combine its Common
     Stock,   the  Conversion   Price  and  the   Conversion   Shares  shall  be
     proportionately adjusted.

          (c) Stock  Dividends  and  Distributions.  If the  Company at any time
     while this Note is outstanding shall issue or pay the holders of its Common
     Stock,  or take a record of the holders of its Common Stock for the purpose
     of entitling them to receive,  a dividend payable in, or other distribution
     of,  Common  Stock,  then (i) the  Conversion  Price  shall be  adjusted in
     accordance with Section 6(e) and (ii) the number of Conversion Shares shall
     be adjusted to the number of shares of Common  Stock that the Holder  would
     have owned  immediately  following such action had this Note been converted
     immediately prior thereto.

                                        7







          (d) Stock and Rights  Offering to  Shareholders.  If at any time after
     the date of issuance of this Note,  the Company shall issue or sell, or fix
     a record date for the purposes of entitling  holders of its Common Stock to
     receive, (i) Common Stock or (ii) rights, options or warrants entitling the
     holders  thereof to subscribe for or purchase  Common Stock (or  securities
     convertible or exchangeable  into or exercisable for Common Stock),  in any
     such  case,  at a price per  share (or  having a  conversion,  exchange  or
     exercise price per share) that is less than the lowest Closing Price during
     the twenty (20) consecutive trading days immediately  preceding the date of
     such issuance or sale or such record date then,  immediately after the date
     of such issuance or sale or on such record date, (A) the  Conversion  Price
     shall be adjusted in  accordance  with  Section  6(e) and (B) the number of
     Conversion   Shares  shall  be  adjusted  to  that  number   determined  by
     multiplying the number of Conversion Shares  immediately before the date of
     such issuance or sale or such record date by a fraction, the denominator of
     which will be the number of shares of Common Stock outstanding on such date
     plus the number of shares of Common Stock that the aggregate offering price
     of the total number of shares so offered for  subscription  or purchase (or
     the aggregate initial conversion price, exchange price or exercise price of
     the convertible securities or exchangeable securities or rights, options or
     warrants,  as the case may be, so offered)  would  purchase at such Closing
     Price,  and the  numerator  of which will be the number of shares of Common
     Stock  outstanding  on such date plus the  number of  additional  shares of
     Common  Stock  offered  for  subscription  or  purchase  (or into which the
     convertible or  exchangeable  securities or rights,  options or warrants so
     offered are initially  convertible or exchangeable  or exercisable,  as the
     case may be).

          If the  Company  shall at any time after the date of  issuance of this
     Note  distribute  to all holders of its Common  Stock any shares of capital
     stock  of the  Company  (other  than  Common  Stock)  or  evidences  of its
     indebtedness or assets (excluding cash dividends or distributions paid from
     retained  earnings  or  current  year's  or prior  year's  earnings  of the
     Company)  or rights or  warrants to  subscribe  for or purchase  any of its
     securities  (excluding  those  referred  to in  the  immediately  preceding
     paragraph)(any  of the foregoing being hereinafter in this paragraph called
     the "Securities"), then in each such case, the Company shall reserve shares
     or other  units of such  securities  for  distribution  to the Holder  upon
     conversion  of this Note so that, in addition to the shares of Common Stock
     to which such  Holder is  entitled,  such  Holder  will  receive  upon such
     exercise  the amount and kind of such  Securities  which such Holder  would
     have received if the Holder had,  immediately  prior to the record date for
     the distribution of the Securities, converted this Note.

          (e)  Conversion  Price  Adjustment.  Whenever the number of Conversion
     Shares is adjusted,  as herein provided,  the Conversion Price payable upon
     the  conversion of this Note shall be adjusted to that price  determined by
     multiplying the Conversion Price  immediately prior to such adjustment by a
     fraction  (i) the  numerator  of which  shall be the  number of  Conversion
     Shares  immediately  prior to such adjustment,  and (ii) the denominator of
     which shall be the number of Conversion Shares immediately thereafter.

          (f) 1996 EBITDA Adjustment. The Conversion Price shall additionally be
     adjusted in the following circumstances:

                                        8








               (i) if the  Company  shall  achieve  1996 EBITDA (as such term is
          defined in Section  13(h)) in an amount of less than  $6,000,000,  the
          Conversion Price shall be reduced to $1.50 per share; and

               (ii) if the  Company  shall  achieve  1996 EBITDA in an amount of
          less than $4,750,000  (together with the $6,000,000 amount referred to
          above, the "Adjusted Amounts"),  the Conversion Price shall be reduced
          to $1.00 per share;

     provided,  however,  that in the event the Company sells all of the capital
     stock  or all or  substantially  all of the  assets  of one or  more of its
     Subsidiaries in 1996, the Adjusted  Amounts for 1996 will be reduced by the
     amount  or  amounts  set  forth in  Schedule  A hereto  in  respect  of the
     Subsidiary or Subsidiaries  so involved.  In the event any such sale occurs
     during 1996, the applicable  Adjusted Amount will be reduced by multiplying
     it by a fraction,  the numerator of which is the number of days of the year
     remaining after any such sale and the denominator is 365.

          (g)  Certain  Shares  Excluded.  The number of shares of Common  Stock
     outstanding at any given time for purposes of the  adjustments set forth in
     this Section 6 shall exclude any shares then directly or indirectly held in
     the treasury of the Company.

          (h) Deferral and  Cumulation  of De Minimis  Adjustments.  The Company
     shall not be required to make any adjustment  pursuant to this Section 6 if
     the amount of such  adjustment  should be less than one percent (1%) of the
     Conversion  Price  in  effect  immediately  before  the  event  that  would
     otherwise have given rise to such adjustment.  In such case,  however,  any
     adjustment that would otherwise have been required to be made shall be made
     at the time of and  together  with the next  subsequent  adjustment  which,
     together  with any  adjustment or  adjustments  so carried  forward,  shall
     amount to not less than one percent (1%) of the Conversion  Price in effect
     immediately   before  the  event  giving  rise  to  such  next   subsequent
     adjustment.

          (i) Duration of Adjustment. Following each computation or readjustment
     provided in this Section 6, the new adjusted Conversion Price and number of
     Conversion  Shares shall remain in effect  until a further  computation  or
     readjustment thereof is required.

          (j)  Reservation.  The Company  hereby  agrees that at all times there
     shall be reserved for issuance upon the conversion of this Note such number
     of  shares of its  Common  Stock as shall be  required  for  issuance  upon
     conversion of this Note.  The Company  further agrees that all shares which
     may be issued upon the  conversion of the rights  represented  by this Note
     will be duly  authorized and will, upon issuance and against payment of the
     Conversion Price, be validly issued,  fully paid and  non-assessable,  free
     from all taxes,  liens,  charges and preemptive  rights with respect to the
     issuance thereof, other than taxes, if any, in

                                        9







     respect of any transfer occurring  contemporaneously with such issuance and
     other than transfer  restrictions  imposed by federal and state  securities
     laws.

          (i) Delivery of Shares  and/or New Note.  The Company  shall deliver a
     certificate  or  certificates  for shares of its Common  Stock  issuable on
     conversion of this Note as soon as practicable after surrender of this Note
     for  conversion,  but the person or persons to whom such  certificates  are
     issuable  shall be considered  the holder of record of the shares of Common
     Stock from the time this Note is  surrendered.  Except as described  above,
     this Note is not otherwise  convertible  into shares of Common Stock.  Upon
     conversion  of only a portion of this Note,  the  Company  shall  issue and
     deliver to, or upon the written order of, the Holder hereof, at the expense
     of the Company,  a new Note covering the principal  amount of this Note not
     converted,  which new Note shall entitle the holder  thereof to interest on
     the  principal  amount  thereof  to the same  extent as if the  unconverted
     portion of this Note had not been surrendered for conversion.

         7. Notices to Holders.

         (a) Notice of Record Date. In case:

          (i) the Company shall take a record of the holders of its Common Stock
     (or other stock or securities at the time receivable upon the conversion of
     this Note) for the purpose of entitling them to receive any dividend (other
     than a cash dividend payable out of earned surplus of the Company) or other
     distribution, or any right to subscribe for or purchase any shares of stock
     of any class or any other securities, or to receive any other right;

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

          (iii) of any voluntary  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 hereof at the time outstanding 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 time, if any, is to be fixed,  as of which
the holders of record of Common Stock (or such stock or  securities  at the time
receivable upon the conversion of this Note) shall be entitled to exchange their
shares of Common Stock (or such other stock or  securities)  for  securities  or
other  property   deliverable   upon  such   reorganization,   reclassification,
consolidation,  merger, conveyance, dissolution, liquidation or winding-up. Such
notice shall be mailed at least

                                       10







thirty (30) days prior to the record  date  therein  specified,  or if no record
date shall have been specified therein,  at least thirty (30) days prior to such
other specified date.

         (b)  Certificate  of Adjustment.  Whenever the Conversion  Price or the
number of Conversion Shares shall be adjusted pursuant to Section 6 hereof,  the
Company  shall  promptly  make a  certificate  signed by its President or a Vice
President  and by its  Treasurer  or  Assistant  Treasurer  or its  Secretary or
Assistant Secretary,  setting forth in reasonable detail the event requiring the
adjustment,  the amount of the  adjustment,  the method by which such adjustment
was  calculated  and the number of Conversion  Shares and the  Conversion  Price
after giving effect to such adjustment,  and shall promptly cause copies of such
certificates to be mailed (by first class mail postage prepaid) to the Holder of
this Note.

         8.  Registration,  Exchange  and  Transfer.  The  Company  will  keep a
register in which,  subject to such reasonable  regulations as it may prescribe,
it will  register all Notes.  No transfer of this Note shall be valid as against
the  Company  unless  made  upon  the  register.  This  Note is  subject  to the
restrictions on transfer of this Note and compliance  with said  restrictions on
transfer, the Company shall execute and deliver in the name of the transferee or
transferees a new Note or Notes for a like principal amount.

         This Note may be exchanged  for a like  aggregate  principal  amount in
other  denominations.  To be exchanged,  this Note shall be surrendered for that
purpose at the  principal  office of the Company,  and the Company shall execute
and deliver in exchange  therefor the Note or Notes which the holder  making the
exchange   shall  be   entitled   to  receive,   bearing   serial   numbers  not
contemporaneously outstanding.

         This Note, if presented for transfer, exchange,  redemption or payment,
shall (if so required by the Company) be duly endorsed by, or be  accompanied by
instruments  of transfer in form  satisfactory  to the Company duly executed by,
the registered Holder or by his duly authorized attorney.

         The  Company  may deem and treat the  registered  Holder  hereof as the
absolute  owner  hereof   (whether  or  not  this  Note  shall  be  overdue  and
notwithstanding  any  notation of ownership  or other  writing  hereon by anyone
other than the Company),  for the purpose of receiving  payment of or on account
of the principal hereof and interest hereon,  for the conversion  hereof and for
all other  purposes,  and the Company shall not be affected by any notice to the
contrary.

         9.  Covenants.  The  Company  covenants,  so long as this Note shall be
outstanding  and unless the Holders of more than  seventy-five  percent (75%) of
the aggregate  principal  amount of all Notes then  outstanding  shall otherwise
approve, that:

          (a)  Financial  Statements,  Reports,  etc. So long as this Note shall
     remain outstanding and the Company is subject to the filing requirements of
     Section 13(a),  13(c) or 15(d) of the  Securities  Exchange Act of 1934, as
     amended (the "Exchange Act"), the Company

                                       11







     will transmit or cause to be transmitted to the Holder,  promptly after the
     same are sent or become publicly available, copies of any and all financial
     statements and reports which are made available to its shareholders and all
     periodic and other reports, proxy statements,  registration  statements and
     other materials filed by it with the Securities and Exchange Commission, or
     any other governmental  authority succeeding to any or all of the functions
     of said commission, or any national securities exchange or stock market, as
     the case may be. If the Company is not subject to filing requirements,  the
     Company will transmit or cause to be  transmitted  to the Holder annual and
     quarterly  reports  containing  audited  annual  financial  statements  and
     related  notes  thereto  and  unaudited  quarterly  financial   statements,
     respectively.

          (b)  Registration  of Shares.  The Company  shall file a  registration
     statement with the Securities and Exchange  Commission under the Securities
     Act of 1933, as amended (the "Act"),  with respect to the Notes, the shares
     of Common  Stock  issuable  pursuant  hereto,  the  Warrant  referred to in
     Section 16(a) and the shares of Common Stock  issuable upon the exercise of
     the  Warrant  on or prior to the later of (i)  ninety  (90) days  after the
     Company's  receipt of the net proceeds from the initial sale of the minimum
     principal  amount  of the  Notes or (ii)  March  31,  1996,  pursuant  to a
     registration  rights agreement of even date herewith between the Holder and
     the Company.

          (c)  Corporate  Existence.  The  Company  shall,  and shall  cause its
     Subsidiaries  to, do or cause to be done all things  necessary to preserve,
     renew and keep in full force and effect its corporate  existence,  material
     rights,  licenses,  permits  and  franchises  and  comply  in all  material
     respects with all laws and regulations applicable to it.

          (d) Taxes and  Assessments.  The  Company  shall,  and shall cause its
     Subsidiaries to, pay and discharge all taxes,  assessments and governmental
     charges  or levies  imposed  upon it or upon its  income or  profits  or in
     respect of its  property,  before the same shall become in default  (which,
     for purposes of this Note,  shall mean the earlier of ninety (90) days from
     its due date or  invoice  date,  as the case may be, or the date upon which
     such obligee  commences an action or  proceeding  to recover such  amount),
     provided,  however,  that the  Company  shall  not be  required  to pay and
     discharge or to cause to be paid and discharged  any such tax,  assessment,
     charge,  levy or claim so long as the validity or amount  thereof  shall be
     contested in good faith by  appropriate  proceedings  (if the Company shall
     have set aside on its books adequate reserves therefor).

          (e) Liens.  The  Company  shall  not,  and shall not permit any of its
     Subsidiaries to, incur,  create,  assume or suffer to exist any Lien on any
     property  or  assets,  income  or  profits  of the  Company,  now  owned or
     hereafter acquired, other than Permitted Liens.

          (f)  Indebtedness.  The Company shall not, and shall not permit any of
     its Subsidiaries to, contract, create, incur, assume or suffer to exist any
     Indebtedness,  except for (i) Senior Indebtedness;  (ii) Indebtedness under
     this Note and the  other  Notes in an  aggregate  principal  amount  not to
     exceed $9,500,000; (iii) Indebtedness between Subsidiaries and between

                                       12







     any  Subsidiary  and the Company;  (iv)  Indebtedness  existing on the date
     hereof;  (v) Indebtedness of Lynwood  Scientific  Developments  Limited,  a
     corporation organized under the laws of the United Kingdom, to Midland Bank
     plc. in an aggregate  amount not to exceed  $2,000,000  or the U.S.  dollar
     equivalent in English pounds; (vi) Indebtedness of Codar Technology,  Inc.,
     a Colorado  corporation,  to MetLife  Capital Corp.  and Colorado  National
     Leasing,  Inc. in an aggregate amount not to exceed  $1,200,000;  and (vii)
     all extensions, renewals and refundings of any of the foregoing.

          (g)  Investments.  The Company  shall not, and shall not permit any of
     its Subsidiaries to, purchase,  hold or acquire any capital stock, evidence
     of indebtedness  or other  securities of, make or permit to exist any loans
     or  advances  to,  or make or permit  to exist  any  investment  (by way of
     transfers of property, contributions to capital, acquisitions of businesses
     or acquisitions of assets other than in the ordinary course of business, or
     otherwise) or any other interest in, any other Person, except for Permitted
     Investments.

          (h)  Payments.  The Company shall not, and shall not permit any of its
     Subsidiaries to, declare or pay,  directly or indirectly,  any dividends or
     make  any  other  distribution  or  payment,  whether  in  cash,  property,
     securities or a combination thereof,  with respect to (whether by reduction
     of capital or  otherwise)  any  shares of  capital  stock (or any  options,
     warrants,  rights or other equity securities or agreements  relating to any
     capital stock) now or hereafter outstanding, or purchase, redeem, retire or
     otherwise  acquire for value any shares of its capital stock or warrants or
     options therefor now or hereafter outstanding, or set apart any sum for the
     aforesaid  purposes,  in any fiscal  year,  provided  that the  Company may
     declare  stock  splits and pay  dividends  payable  solely in shares of any
     class of its capital stock and the Subsidiaries may make cash distributions
     or payments to the Company.

          (i) Disposition of Assets. The Company shall not, and shall not permit
     any of its  Subsidiaries  to,  sell or  otherwise  dispose  of any  assets,
     including  the  capital  stock of any of its  Subsidiaries,  except for (i)
     sales of  inventory,  fixtures  and  equipment  in the  ordinary  course of
     business,  (ii) sales of assets having a book value not exceeding  $100,000
     in the aggregate,  and (iii) the sale of certain  vacant  property owned by
     the Company located in Hauppauge, New York.

          (j) Affiliate Transactions. Subsequent to the date hereof, the Company
     shall not, and shall not permit any Subsidiary to,  directly or indirectly,
     enter  into or  permit  to exist  any  transaction  or  series  of  related
     transactions (including, but not limited to, the purchase, sale or exchange
     of property,  the making of any investment,  the giving of any guarantee or
     the rendering of any service) with any Affiliate of the Company (other than
     transactions among the Company and any wholly-owned  Subsidiary) unless (i)
     such  transaction  or series of  related  transactions  is on terms no less
     favorable  to the  Company  or such  Subsidiary  than  those  that could be
     obtained in a comparable arm's length transaction with a Person that is not
     an Affiliate,  and (ii) such transaction or series of related  transactions
     is  approved  by a  majority  of the  Board  of  Directors  of the  Company
     (including a majority of the  disinterested  directors),  which approval is
     set  forth  in a board  resolution  of the  Company  certifying  that  such
     transaction  or  series  of  transactions  complies  with  the  immediately
     preceding clause (i).

                                       13








          (k) Merger, Consolidation, etc. Neither the Company nor any Subsidiary
     shall consolidate or merge with, or convey, transfer or lease substantially
     all of its assets in a single transaction or series of transactions to, any
     other Person unless (i) the successor  formed by such  consolidation or the
     survivor of such merger or the Person that acquires by conveyance, transfer
     or lease substantially all of the assets of the Company as an entirety,  as
     the case may be (the  "Successor"),  shall have  executed and  delivered to
     Holder  its  assumption  of the due  and  punctual  performance  of all the
     obligations  under this Note,  (ii) such  Successor  shall be a corporation
     organized and existing under the laws of the United States of America,  any
     state thereof or the District of Columbia,  and (iii) no event  referred to
     in Section 8 shall have occurred and be continuing.

          (l) Maintenance of Properties. The Company shall, and shall cause each
     of its Subsidiaries  to, keep all properties  useful in the business of the
     Company in good  working  order and  condition  except to the  extent  that
     discontinuing  the operation or maintenance  of any such  properties is, in
     the judgment of the Company, desirable in the conduct of its business.

         10. Events of Default. (a) In the event that:

          (i) the Company defaults in the payment of any installment of interest
     required  to be made on this Note and such  default  shall  continue  for a
     period of ten (10) days;

          (ii) the Company  defaults in making any payment of  principal on this
     Note required to be made on this Note;

          (iii) any  obligation of the Company or any Subsidiary for the payment
     of borrowed  money in excess of  $500,000  becomes or is declared to be due
     and payable  prior to its  expressed  maturity,  unless the validity of any
     such  indebtedness  or  obligation  is  being  contested  in good  faith by
     appropriate proceedings;

          (iv) any warrant of attachment, execution or other writ is levied upon
     any  property  or  assets of the  Company  or any  Subsidiary  in excess of
     $500,000 and is not discharged or stayed  (including  stays  resulting from
     the filing of an appeal) within thirty (30) days;

          (v) all or any  substantial  part of the assets or  properties  of the
     Company or any  Subsidiary  are condemned,  seized or  appropriated  by any
     government  or  governmental  authority;  or any  order is  entered  in any
     proceeding  directing  the  winding-up,  dissolution  or  split-up  of  the
     Company;

          (vi) the Company or any Subsidiary  hereafter  makes an assignment for
     the benefit of  creditors,  or files a petition in bankruptcy as to itself,
     is  adjudicated  insolvent  or bankrupt,  petitions  any receiver of or any
     trustee for the Company

                                       14







     or  any  substantial  part  of  the  property  of  the  Company  under  any
     bankruptcy, reorganization,  arrangement, readjustment of debt, dissolution
     or liquidation law or statute of any jurisdiction, whether or not hereafter
     in effect; or if there is hereafter  commenced against the Company any such
     proceeding  and  an  order  approving  the  petition  is  entered  or  such
     proceeding  remains  undismissed  for a period of sixty (60)  days,  or the
     Company by any act or omission to act  indicates its consent to or approval
     of or  acquiescence  in  any  such  proceeding  or the  appointment  of any
     receiver  of, or trustee for,  the Company or any  substantial  part of its
     properties,  or suffers any such  receivership  or  trusteeship to continue
     undischarged for a period of sixty (60) days; or

          (vii) the Company  defaults in the due observance or  performance,  in
     any  material  respect,  of any  covenant,  condition  or  agreement  to be
     observed  or  performed  pursuant  to the terms of this Note  (other than a
     default  which is  specifically  provided  for in this Section 10) and such
     default  continues  unremedied  for more than thirty (30) days after notice
     thereof to the Company;

then, and in each and every such case,  the holders of not less than  one-fourth
(1/4) in  aggregate  principal  amount  of  outstanding  Notes may  declare  the
principal and accrued but unpaid interest of all the Notes to be due and payable
immediately, by written notice to the Company, and upon any such declaration the
same  shall  become and shall be  immediately  due and  payable,  subject to the
subordination provisions of Section 4 hereof. At any time after such declaration
of  acceleration  has been made,  and before a judgment or decree for payment of
money due has been  obtained,  the holders of a majority in aggregate  principal
amount of the outstanding  Notes may, by written notice to the Company,  rescind
and annul such declaration.

         (b) At any time  before the date of any  declaration  accelerating  the
maturity of this Note:  (i) the  holders of at least  sixty-six  and  two-thirds
percent (66.67%) in aggregate  principal  amount of outstanding  Notes may waive
any past Event of Default  and its  consequences  pertaining  to the  payment of
interest on, or the  principal  of, any of the Notes;  and (ii) the holders of a
majority  in  aggregate  principal  amount of Notes may waive any other Event of
Default  hereunder.  Such waivers shall be evidenced by written  notice or other
document  specifying  the Event or Events of Default  being  waived and shall be
binding on all existing or subsequent holders of outstanding Notes.

         11. Certain Consequences Upon Default.

         (a) Defaulted  Interest.  Subject to the  provisions of Section 4 and 5
hereof,  if the  Company  shall  default in the payment of the  principal  of or
interest on this Note,  whether upon maturity,  by  acceleration,  or otherwise,
including,  without  limitation,  as a  result  of a  Chapter  11 or  Chapter  7
bankruptcy  case  commenced by or against the Company in which it is the debtor,
the  Company  shall on demand  from  time to time pay  interest,  to the  extent
permitted by law, on such defaulted amount up to (but not including) the date of
actual  payment  (whether  before  or after  judgment)  at the  rate  per  annum
(computed on the basis of the actual

                                       15







number  of days  elapsed  over a year of 360  days) at the rate set forth in the
introduction of this Note, plus six percentage  points (6%). It is the intention
of the Company and the holder of this Note to comply with applicable  usury laws
(now or hereafter  enacted);  accordingly,  notwithstanding any provision to the
contrary in this Note, and any other document  executed in connection  herewith,
in no event  shall this Note or any such other  document  require the payment or
permit the collection of interest in excess of the maximum  amount  permitted by
such laws. If for any circumstances whatsoever,  fulfillment of any provision of
this  Note  or of any  such  other  document  at the  time  performance  of such
provision  shall be due,  shall  involve  transcending  the  limit  of  validity
prescribed by law for the collection or charging of interest,  then, ipso facto,
the  obligation to be fulfilled  shall be reduced to the limit of such validity,
and if for any such  circumstances  the holder of this Note  shall ever  receive
anything of value as interest or deemed  interest by  applicable  law under this
Note or any such other  document or  otherwise  an amount that would  exceed the
highest  lawful  rate,  such amount that would be  excessive  interest  shall be
applied to the  reduction  of the  principal  amount owing under this Note or on
account of any other  indebtedness of the Company to such holder, and not to the
payment of interest, or if such excessive interest exceeds the unpaid balance of
principal of such indebtedness, such excess shall be refunded to the Company. In
determining  whether or not the  interest  paid or payable  with  respect to any
indebtedness  of the  Company to the  Holder,  under any  specific  contingency,
exceeds the highest  lawful  rate,  the  Company and such holder  shall,  to the
maximum extent permitted by applicable law, (i)  characterize any  non-principal
payment as an expense,  fee or premium  rather than as  interest,  (ii)  exclude
voluntary prepayments and the effects thereof, (iii) amortize, prorate, allocate
and  spread  the  total  amount  of  interest  throughout  the full term of such
indebtedness  so that the  actual  rate of such  interest  does not  exceed  the
maximum  amount  permitted by  applicable  law,  and/or (iv)  allocate  interest
between  portions of such  indebtedness,  to the end that no such portion  shall
bear interest at a rate greater than that permitted by applicable law.

         (b) Additional  Director  Nominee.  If and whenever interest payable on
this Note shall be in arrears in whole or in part,  or if the Company shall fail
to pay the  principal of this Note  (whether or not  prevented  from doing so by
restrictions contained in its Restated Certificate of Incorporation,  as amended
from time to time, or any other agreement or instrument),  the existing  members
of the Board of Directors  shall cause one Director then serving on the Board of
Directors  (who has not been  designated  by the  holders  of Notes,  Charles S.
Holmes or C.  Shelton  James) to resign as a  director,  and the  holders of the
Notes  shall be  entitled  to  immediately  appoint  one  Director  to fill such
vacancy, provided, that if such Director appointed by the holders, together with
the other  directors  designated by the holders of Notes and Messrs.  Holmes and
James, would not exceed 50% of the total Board of Directors,  then in such event
the holders of Notes shall be entitled to appoint additional Directors (upon the
resignation of other  non-designated  existing  Directors) so as its and Messrs.
Holmes'  and  James'  designees  constitute  a  majority  of the total  Board of
Directors.  Whenever all arrears in interest on the Notes then outstanding shall
have been paid and all principal amounts required to be made with respect to any
Notes shall have been made or funds  therefor  set apart for  payment,  then the
right  of the  holders  of  Notes  to  designate  one  Director  (or two or more
Directors,  as the case may be)  shall  cease  (but  subject  always to the same
provisions for the vesting of such rights in

                                       16







the case of any  similar  future  arrearages  in interest or failures to satisfy
principal  obligations),  and the  terms of  office of all  persons  elected  as
Directors by the holders of Notes shall  forthwith  terminate  and the number of
members on the Board of Directors appointed by the holders of the Notes shall be
reduced  accordingly.  At any time after such power shall have been so vested in
the Notes, the Secretary of the Corporation may, and upon the written request of
any holder of Notes  (addressed to the Secretary at the principal  office of the
Company) shall,  call a special meeting of the holders of Notes for the election
of the Director (or two or more Directors,  as the case may be) to be designated
by them as  herein  provided,  such call to be made by  notice  similar  to that
provided in the By-laws for a special meeting of the shareholders or as required
by law. If any such  special  meeting  required  to be called as above  provided
shall not be called by the Secretary  within  fifteen (15) days after receipt of
any such  request,  then any  holder of Notes may call  such  meeting,  upon the
notice above provided, and for that purpose shall have access to the register of
holders of the Notes of the  Company.  The  Director(s)  designated  at any such
special  meeting  shall  hold  office  until  the  next  annual  meeting  of the
shareholders  or  special  meeting  held  in  place  thereof  and be  re-elected
successively thereafter,  if such office shall not have previously terminated as
above provided.  In case any vacancy shall occur among the Directors  designated
by the holders of Notes, a successor  shall be elected by the Board of Directors
to serve until the next annual meeting of the  shareholders  or special  meeting
held in place  thereof  upon the  nomination  of the  then  remaining  Directors
designated by the holders of Notes and Messrs. Holmes and James.

         (c) Additional Warrants.  In the event there occurs an Event of Default
pertaining to the payment of interest on, or the principal of, any of the Notes,
the  Company  shall  issue to the  holders of the Notes  additional  warrants to
purchase  2,000,000 shares of Common Stock,  each holder to receive his pro rata
share.

         12. Investment Representations.

         (a) The Holder hereby  acknowledges  that this Note and the  Conversion
Shares  are not  being  registered  (i)  under  the Act on the  ground  that the
issuance of the Note is exempt from  registration  under Section 4(2) of the Act
as not  involving  any  public  offering  or (ii)  under  any  applicable  state
securities  law  because  the  issuance of this Note does not involve any public
offering;  and that the Company's  reliance on the Section 4(2) exemption of the
Act and under  applicable  state  securities  laws is  predicated in part on the
representations  hereby made to the  Company by the Holder that it is  acquiring
this Note for  investment  for its own  account,  with no present  intention  of
dividing its  participation  with others or reselling or otherwise  distributing
the same,  provided,  nevertheless,  subject to any  requirement of law that the
disposition of its property shall at all times be within its control.

         (b) The Holder  hereby  agrees that it will not sell or transfer all or
any part of this Note and/or  Conversion Shares unless and until, and so long as
such securities are not covered by an effective registration statement under the
Act, it shall first have given  notice to the  Company  describing  such sale or
transfer  and  furnished  to  the  Company  either  (i) an  opinion,  reasonably
satisfactory to counsel for the Company, of counsel (skilled in securities

                                       17







matters,  selected by the Holder and reasonably  satisfactory to the Company) to
the effect that the proposed  sale or transfer may be made without  registration
under the Act and without  registration or qualification under any state law, or
(ii) an interpretive  letter from the Securities and Exchange  Commission to the
effect that no  enforcement  action will be  recommended if the proposed sale or
transfer is made without registration under the Act.

         (c)  If,  at  the  time  of  issuance  of  the  Conversion  Shares,  no
registration statement is in effect with respect to such shares under applicable
provisions  of the Act,  the Company  may at its  election  require  that Holder
provide the Company  with  written  reconfirmation  of the  Holder's  investment
intent and that any stock certificate delivered to the Holder upon conversion of
this Note shall bear legends reading substantially as follows:

                  "TRANSFER OF THE SHARES  REPRESENTED  BY THIS  CERTIFICATE  IS
                  SUBJECT TO CERTAIN RESTRICTIONS SET FORTH IN THE NOTE PURSUANT
                  TO WHICH THESE  SHARES WERE ISSUED BY THE  COMPANY.  COPIES OF
                  THOSE RESTRICTIONS ARE ON FILE AT THE PRINCIPAL OFFICES OF THE
                  COMPANY,   AND  NO   TRANSFER   OF  SUCH  SHARES  OR  OF  THIS
                  CERTIFICATE,   OR  OF  ANY  SHARES  OR  OTHER  SECURITIES  (OR
                  CERTIFICATES THEREFOR) ISSUED IN EXCHANGE FOR OR IN RESPECT OF
                  SUCH SHARES, SHALL BE EFFECTIVE UNLESS AND UNTIL THE TERMS AND
                  CONDITIONS THEREIN SET FORTH SHALL HAVE BEEN COMPLIED WITH."

                  "THE  SHARES  REPRESENTED  BY THIS  CERTIFICATE  HAVE NOT BEEN
                  REGISTERED  UNDER THE  SECURITIES  ACT OF 1933, AND MAY NOT BE
                  SOLD,  TRANSFERRED,  PLEDGED OR  OTHERWISE  DISPOSED OF IN THE
                  ABSENCE  OF AN  EFFECTIVE  REGISTRATION  STATEMENT  UNDER  THE
                  SECURITIES  ACT OF 1933 OR AN OPINION OF COUNSEL  SATISFACTORY
                  TO THE ISSUER OF THIS  CERTIFICATE  THAT  REGISTRATION  IS NOT
                  REQUIRED UNDER SAID ACT."

In addition, so long as the foregoing legend may remain on any stock certificate
delivered to the Holder,  the Company may maintain  appropriate  "stop transfer"
orders with respect to such certificates and the shares  represented  thereby on
its books and  records  and with  those to whom it may  delegate  registrar  and
transfer functions.

         (d) The Company may refuse to  recognize a transfer of this Note or any
Conversion  Shares on its books should a holder attempt to transfer this Note or
any Conversion Shares otherwise than in compliance with this Section 12.

                                       18







         13. Definitions. As used herein, unless the context otherwise requires,
the following terms have the respective meanings:

          (a) "Affiliate":  with respect to any Person,  the following:  (i) any
     other Person that at such time directly or  indirectly  through one or more
     intermediaries  controls,  or is controlled  by or is under common  control
     with such first Person or (ii) any Person  beneficially  owning or holding,
     directly  or  indirectly,  10% or more of any  class of  voting  or  equity
     interests of the Company or any Subsidiary or any  corporation of which the
     Company and its  Subsidiaries  beneficially  own or hold, in the aggregate,
     directly  or  indirectly,  10% of more of any  class of  voting  or  equity
     interests.  As used in such  definition,  "controls",  "controlled  by" and
     "under common control",  as used with respect to an Person,  shall mean the
     possession,  directly  or  indirectly,  of the power to direct or cause the
     direction of the management  policies of such Person,  whether  through the
     ownership of voting securities, by agreement or otherwise.

          (b) "Change in Control": any of the following events or circumstances:
     (i)  individuals  who, at the beginning of any period of  twenty-four  (24)
     consecutive  months,  constitute the Company's board of directors (together
     with any new director whose election by the Company's board of directors or
     whose nomination for election by the Company's shareholders was approved by
     a vote of at least  two-thirds  of the  directors  then still in office who
     either were  directors at the beginning of such period or whose election or
     nomination  for election was  previously so approved)  cease for any reason
     (other than death or  disability) to constitute a majority of the Company's
     board of  directors  then in office;  (ii) any  person or  related  persons
     constituting  a group (as such terms are used the Exchange  Act) become the
     "beneficial owners" (as such term is used under the Exchange Act), directly
     or indirectly of more than fifty percent (50%) of the total voting power of
     all classes then  outstanding of the Company's  voting stock;  or (iii) the
     acquisition  after  the  date  hereof  by any  person  or  related  persons
     constituting  a group of the power to elect,  appoint or cause the election
     or  appointment  of at least a  majority  of the  members  of the  board of
     directors of the Company,  or (iv) the acquisition after the date hereof by
     any person or related persons  constituting a group of all or substantially
     all of the properties and assets of the Company and its Subsidiaries,  on a
     consolidated basis;  provided,  however, that no Change in Control shall be
     deemed to have  occurred in  connection  with,  or pursuant to, the initial
     issuance and sale of the Notes.

          (c)  "Closing  Price":  the closing  price per share of the  Company's
     Common Stock on the  principal  national  securities  exchange on which the
     Common  Stock is listed or  admitted to trading or, if not listed or traded
     on any  such  exchange,  on the  National  Market  System  of the  National
     Association of Securities  Dealers Automated  Quotations System ("Nasdaq"),
     or if not listed or traded on any such  exchange or system,  the average of
     the bid and asked price per share on Nasdaq or, if such  quotations are not
     available,  the fair market value per share of Common  Stock as  reasonably
     determined by the Board of Directors of the Company.

          (d)  "Consolidated  Net  Income":  the net income (or  deficit) of the
     Company and its Subsidiaries  for any period (taken as a cumulative  whole)
     after deducting,

                                       19







     without duplication,  all operating expenses,  provisions for all taxes and
     reserves  (including  reserves  for  deferred  income  taxes) and all other
     proper deductions, all determined in accordance with GAAP on a consolidated
     basis,  after  eliminating  all  intercompany  items  and  after  deducting
     portions of income properly attributable to outside minority interests,  if
     any, in any Subsidiaries;  provided,  however, that there shall be excluded
     (i) any income or deficit of any other Person  accrued prior to the date it
     becomes a  Subsidiary  or merges into or  consolidates  with the Company or
     another  Subsidiary  of the  Company,  (ii) the income (or  deficit) of any
     other Person  (other than a Subsidiary of the Company) in which the Company
     or any Subsidiary has any ownership interest, except to the extent that any
     such income has been actually received by the Company or such Subsidiary in
     the form of cash  dividends  or similar  distributions,  (iii) any deferred
     credit or  amortization  thereof from the  acquisition of any properties of
     assets of any other  Person,  (iv) any  aggregate  net income  (but not any
     aggregate net loss) during such period  arising from the sale,  exchange or
     other  distribution  of capital  assets  (such  term to  include  all fixed
     assets,  whether tangible or intangible,  all inventory sold in conjunction
     with the  disposition of fixed assets and all  securities),  (v) any income
     resulting from the write-up of assets after the date hereof, (vi) any gains
     properly  classified  as  extraordinary  in  accordance  with  GAAP,  (vii)
     proceeds of life  insurance  policies to the extent  such  proceeds  exceed
     premiums paid to maintain such life insurance  policies,  (viii) any income
     of a Subsidiary which is unavailable for the payment of dividends, and (ix)
     any gain arising from the acquisition of securities,  or the extinguishment
     of any  indebtedness  of the  Company  or  any of its  Subsidiaries  or the
     termination of an employee benefit plan.

          (e) "GAAP":  United States generally accepted  accounting  principles,
     consistently applied.

          (f)  "Indebtedness":  at any time and with any  respect to any Person,
     (i)  all  indebtedness  of  such  Person  for  borrowed  money,   (ii)  all
     indebtedness of such Person for the deferred  purchase price of property or
     services (other than property, including inventory, and services purchased,
     and expense  accruals  and  deferred  compensation  items  arising,  in the
     ordinary  course of business,  provided  that the same shall not be overdue
     (i.e.,  the earlier of ninety  (90) days from the invoice  date or the date
     the obligee  commences an action to recover such  amounts),  or if overdue,
     are being  contested in good faith and by appropriate  proceedings),  (iii)
     all  obligations of such Person  evidenced by notes,  bonds,  debentures or
     other similar instruments (other than performance,  surety and appeal bonds
     arising in the ordinary course of business),  (iv) all indebtedness of such
     Person  created  or  arising  under  any  conditional  sale or other  title
     retention  agreement with respect to property acquired by such Person (even
     though the rights and remedies of the seller or lender under such agreement
     in the  event  of  default  are  limited  to  repossession  or sale of such
     property),  (v) all obligations of such Person under leases which have been
     or should be, in accordance with GAAP,  recorded as capital leases,  to the
     extent  required  to be so  recorded,  (vi) all  reimbursement,  payment or
     similar  obligations  of  such  Person,  contingent  or  otherwise,   under
     acceptance,  letter of credit or similar  facilities (vii) all Indebtedness
     referred  to in clauses  (i)  through  (vi) above  guaranteed  directly  or
     indirectly  by  such  Person  including  without   limitation  through  any
     agreement (A) to pay or purchase such  Indebtedness or to advance or supply
     funds for the payment or purchase of such Indebtedness,

                                       20







     (B) to  purchase,  sell or lease (as  lessee  or  lessor)  property,  or to
     purchase or sell services, primarily for the purpose of enabling the debtor
     to make  payment  of such  Indebtedness  or to  assure  the  holder of such
     Indebtedness  against loss in respect of such  Indebtedness,  (C) to supply
     funds  to or in any  other  manner  invest  in the  debtor  (including  any
     agreement  to pay for  property or services  irrespective  of whether  such
     property is received or such  services are  rendered)  or (D)  otherwise to
     assure a creditor against loss in respect of such Indebtedness,  and (viii)
     all Indebtedness  referred to in clauses (i) through (vii) above secured by
     (or for  which the  holder  of such  Indebtedness  has an  existing  right,
     contingent  or  otherwise,  to  be  secured  by)  any  Lien  upon  property
     (including, without limitation, accounts and contract rights) owned by such
     Person,  even though  such Person has not assumed or become  liable for the
     payment of such Indebtedness.

          (g) "Lien": any mortgage,  deed of trust,  pledge,  security interest,
     encumbrance, lien or charge of any kind whatsoever.

          (h) "1996 EBITDA":  Consolidated  Net Income for the fiscal year ended
     December  31,  1996,  plus,  to the extent  deducted  in  determining  such
     Consolidated  Net  Income  and  without  duplication,  (i) the sum for such
     period, of (a) the aggregate amount of all interest (including  capitalized
     interest)  accrued or to accrue  (whether or not actually paid) during such
     period in respect of any Indebtedness of the Company and its  Subsidiaries,
     (b) any amortized  discount in respect of any such  Indebtedness  issued at
     discount,  and (c) any fees or commissions  payable in connection  with any
     letters of credit;  (ii) current and  deferred  taxes on income and profit;
     (iii) depreciation; and (iv) amortization.

          (i) "Notes": the meaning specified in the introduction of this Note.

          (j) "Permitted Investments": any of the following:

               (i) direct  obligations  of, or obligations  the principal of and
          interest on which are unconditionally guaranteed by, the United States
          of America (of by any agency  thereof to the extent  such  obligations
          are  backed by the full  faith  and  credit  of the  United  States of
          America),  in each case maturing within twelve months from the date of
          acquisition thereof;

               (ii)  without  limiting  the  provisions  of clause  (iv)  below,
          investments in commercial paper maturing within one year from the date
          of acquisition  thereof and having,  at such date of acquisition,  the
          highest credit rating  obtainable  from Standard & Poor's  Corporation
          (or  a  similar  rating  by  any  similar   organization  which  rates
          commercial papers);

               (iii)   investments  in  certificates  of  deposits  or  banker's
          acceptances  and time deposits  maturing within twelve months from the
          date of acquisition thereof issued or guaranteed by or placed with (a)
          any domestic  office of the bank with whom the Company  maintains  its
          cash  management  system  or (b)  any  domestic  office  of any  other
          commercial bank of recognized standing organized under the laws of the
          United  States of  America  or any state  thereof  that has a combined
          capital and surplus and undivided profits of not less than

                                       21







          $100,000,000 and is the principal banking subsidiary of a bank holding
          company  having a long-term  unsecured  debt rating of at least "A" or
          the  equivalent  thereof from the Standard & Poor's  Corporation or at
          least "A2" or the equivalent  thereof from Moody's Investors  Service,
          Inc.;

               (iv)  investments in commercial  paper maturing within six months
          from the date of acquisition  and issued by the holding company of any
          commercial bank of recognized standing organized under the laws of the
          United  States of America or any state thereof that has (A) a combined
          capital and surplus in excess of $250,000,000 and (B) commercial paper
          rated at least  "A" or the  equivalent  thereof  from the  Standard  &
          Poor's  Corporation  or at least "A2" or the  equivalent  thereof from
          Moody's  Investors  Service,  Inc.  (or has a  similar  rating  by any
          similar organization that rates commercial paper); or

               (v)  investments  in money  market  funds  substantially  all the
          assets of which are comprised of securities of the types  described in
          clauses (i) through (vi) above.

          (k) "Permitted Lien": means (i) Liens in existence on the date hereof,
     (ii) Liens  created for the benefit of the holders of Senior  Indebtedness,
     (iii)  Liens  imposed  by law for  taxes,  assessments  or  charges  of any
     governmental  authority for claims not yet due or which are being contested
     in good faith by appropriate proceedings and with respect to which adequate
     reserves or other appropriate provisions are being maintained in accordance
     with  GAAP;  (iv)  statutory  Liens of  landlords  and  Liens of  carriers,
     warehousemen, mechanics, materialmen and other Liens imposed by law created
     in the ordinary  course of business for amounts not yet due,  which are not
     overdue by more than sixty (60) days or which are being  contested  in good
     faith by  appropriate  proceedings  and  with  respect  to  which  adequate
     reserves or other appropriate provisions are being maintained in accordance
     with GAAP;  (v) Liens  incurred or deposits made in the ordinary  course of
     business in connection with workers'  compensation,  unemployment insurance
     and other types of social security benefits or to secure the performance of
     tenders,  bids,  leases,   contracts  (other  than  for  the  repayment  of
     indebtedness),  statutory  obligations  and other  similar  obligations  or
     arising as a result of progress payments under government  contracts;  (vi)
     easements  (including,  without limitation,  reciprocal easement agreements
     and utility agreements),  rights-of-way, covenants, consents, reservations,
     encroachments,  variations  and zoning and other  restrictions,  charges or
     encumbrances  (whether or not  recorded),  which in the  aggregate  are not
     substantial  in  amount,  and which do not  interfere  materially  with the
     ordinary conduct of the business of the Company and which do not materially
     detract from the property to which they attach or materially impair the use
     thereof to the  Company;  (vii) Liens  covering  real  property or personal
     property in existence at the time of acquisition thereof by the Company and
     purchase  money  Liens  upon  or in any  property  acquired  or held in the
     ordinary  course of business to secure the purchase  price of such property
     or to secure  indebtedness  permitted by Section 9(g) hereof solely for the
     purpose of  financing  the  acquisition  of such  property and no such Lien
     covers,  or is extended to cover,  any other property owned by the Company;
     and (viii) extensions,  renewals or replacements of any Lien referred to in
     clauses (i) through (vii) above.

                                       22







          (l)  "Person":  any  natural  person,   corporation,   division  of  a
     corporation,  partnership, limited liability company, trust, joint venture,
     association,  company, estate, unincorporated organization or government or
     any agency or political subdivision thereof.

          (m) "Senior  Indebtedness":  the  meaning  specified  in Section  4(a)
     hereof.

          (n)  "Subsidiaries":  with  respect to any  Person,  any  corporation,
     association  or other  business  entity  (whether now existing or hereafter
     organized)  of  which  at  least a  majority  of the  securities  or  other
     ownership  interests  having  ordinary  voting  power for the  election  of
     directors  is, at the time as of which  any  determination  is being  made,
     owned or  controlled  by such  Person or one or more  subsidiaries  of such
     Person.

         14. Notices.

         (a) Notices to Holder of Notes.  Any notice  required by the provisions
of this Note to be given to the  holders of Notes shall be in writing and may be
delivered  by  personal  service  or  sent  by  telegraph  or  cable  or sent by
registered or certified  mail,  return receipt  requested,  with postage thereon
fully  prepaid.  All such  communications  shall be  addressed  to the Holder of
record  at its  address  appearing  on the  books  of the  Company.  If  sent by
telegraph or cable, a confirmed copy of such  telegraphic or cabled notice shall
promptly be sent by mail (in the manner provided  above) to the Holder.  Service
of any such communication made only by mail shall be deemed complete on the date
of actual delivery as shown by the addressee's registry or certification receipt
or at the  expiration of the third (3rd) business day after the date of mailing,
whichever is earlier in time.

         (b) Notices to the Company.  Whenever any  provision of this  agreement
requires  a notice to be given to the  Company  by the  holder of any Note,  the
holder of Common Stock  obtained upon the  conversion of a Note or the holder of
any  other   security   of  the   Company   obtained   in   connection   with  a
recapitalization,  merger, dividend or other event affecting a Note, then and in
each case,  such notice shall be in writing and shall be sent by  registered  or
certified mail,  return receipt  requested with postage thereon fully prepaid to
the Company at its principal place of business.

No notice under this  Section 14 shall be valid  unless  signed by the holder of
the Note,  Common Stock or other security  giving the notice or in the case of a
notice by  holders  of a  specified  percent in  aggregate  principal  amount of
outstanding  Notes  unless  signed by each  holder of a Note whose Note has been
counted in constituting the requisite  percentage of Notes required to give such
Notice.

         15.  Amendment.  With the  consent  of the  holders  of a  majority  in
aggregate principal amount of outstanding Notes, the Company may amend the Notes
to cure any ambiguity,  to correct or supplement any provision therein which may
be  inconsistent  with  any  other  provision  therein,  or to  make  any  other
provisions with respect to matters or questions

                                       23







arising under the Notes which shall not be  inconsistent  with the provisions of
the Notes;  provided such action shall not adversely affect the interests of the
holders of the Notes.

         With the consent of the holders of not less than fifty percent (50%) in
aggregate  principal amount of the outstanding  Notes, the Company may amend the
Notes for the purpose of adding any  provisions to, or changing in any manner or
eliminating any of the provisions of, the Notes; provided, however, that no such
amendment  shall,  without the  consent of the  holders of Senior  Indebtedness,
change the subordination provisions of Sections 4 and 5 hereof or the provisions
referred to in subsection (a) below;  and provided,  further,  that no amendment
shall,  without  the  consent of the holder of each  outstanding  Note  affected
thereby,

          (a) change:  (i) the maturity of the principal of, or any  installment
     of  interest  on,  any  Note;  or (ii) the coin or  currency  in which  the
     principal of or interest on any Note is payable;

          (b) reduce the principal amount thereof or the interest rate thereon;

          (c) increase the Conversion Price thereof; or

          (d) reduce the percentage in principal amount of the outstanding Notes
     the consent of whose  holders is required  for any  amendment  or waiver as
     provided for in the Notes.

         Prompt written notice that this Note has been amended or interpreted in
accordance  with the terms of this Section 15 shall be given to each holder of a
Note. Upon such amendment or interpretation,  the Notes shall be deemed modified
in accordance  therewith,  such amendment or interpretation shall form a part of
this Note for all purposes,  and every subsequent holder of Notes shall be bound
thereby.

         16. Miscellaneous.

         (a)  Contemporaneously  with the  execution  and delivery  hereof,  the
Company has issued to the Holder a detachable warrant  representing the right to
purchase 250 shares of Common Stock at a exercise price equal to $2.50 per share
of Common Stock, subject to adjustment in certain events.

         (b) This  Note  and the  shares  of  Common  Stock or other  securities
issuable upon conversion of this Note will be accorded the  registration  rights
under the Act set forth in that certain  Registration  Rights Agreement  between
the  Company  and the  Holders,  a form of which  agreement  is being  furnished
concurrently herewith.

         (c) This Note is the  obligation of the Company  only,  and no recourse
shall  be  had  for  the  payment  thereof  or  interest   thereon  against  any
shareholder,  officer  or  director  of the  Company,  whether  by virtue of any
constitution, statute, rule or law or otherwise,

                                       24







all such liability,  by the acceptance  hereof, and as part of the consideration
hereof, being expressly waived.

         (d) Upon receipt of evidence reasonably  satisfactory to the Company of
the  loss,  theft,  destruction  or  mutilation  of this Note and of a letter of
indemnity reasonably  satisfactory to the Company, and upon reimbursement to the
Company of all  reasonable  expenses  incident  thereto,  and upon  surrender or
cancellation of this Note, if mutilated, the Company will make and deliver a new
Note of like tenor in lieu of such lost, stolen, destroyed or mutilated Note.

         (e) THIS NOTE AND THE RIGHTS AND OBLIGATIONS OF EACH OF THE COMPANY AND
THE HOLDER  HEREUNDER  SHALL BE CONSTRUED IN ACCORDANCE  WITH AND BE GOVERNED BY
THE LAWS OF THE STATE OF NEW YORK APPLICABLE TO AGREEMENTS AND INSTRUMENTS  MADE
AND TO BE PERFORMED IN NEW YORK AND CANNOT BE MODIFIED OR CHANGED ORALLY.

         IN WITNESS WHEREOF,  the Company has duly caused this Note to be signed
on its behalf, in its corporate name and by its duly authorized  officer,  as of
this _____ day of February 1996.

                                            NAI TECHNOLOGIES, INC.

                                            By:
                                               _________________
                                            Richard A. Schneider
                                            Executive Vice President,
                                            Treasurer and Secretary

                                       25






                                                                      Schedule A

                          Section 6(f) Adjusted Amounts


                                                                                           
Wilcom, Inc............................................................................$  838,000

Codar Technology, Inc..................................................................$2,805,000

NAI Technologies - Systems Division Corporation........................................$  607,000

Lynwood Scientific Developments Limited................................................$1,833,000


                                       26