SIXTH AMENDMENT TO SECOND AMENDED AND RESTATED FINANCING AND SECURITY AGREEMENT

THIS SIXTH AMENDMENT TO SECOND AMENDED AND RESTATED FINANCING AND SECURITY
AGREEMENT (this “Agreement”) is made as of February 28, 2008, by ARGON ST, INC.,
a Delaware corporation, successor to SensyTech, Inc., formerly known as Sensys
Technologies Inc., a Delaware corporation (“Argon”), COHERENT SYSTEM
INTERNATIONAL, LLC, a Delaware limited liability company (“Coherent”), and BANK
OF AMERICA, N. A., a national banking association (the “Lender”).

RECITALS

A. Argon and Lender entered into a Second Amended and Restated Financing and
Security Agreement dated as of February 28, 2002, as modified pursuant to a
First Amendment to Second Amended and Restated Financing and Security Agreement
dated as of February 28, 2003, a Second Amendment to Second Amended and Restated
Financing and Security Agreement dated as of March 31, 2003, a Third Amendment
to Second Amended and Restated Financing and Security Agreement dated as of
February 28, 2004, a Fourth Amendment to Second Amended and Restated Financing
and Security Agreement dated as of February 28, 2006 and a Fifth Amendment to
Second Amended and Restated Financing and Security Agreement (the “Fifth
Amendment”) dated as of March 31, 2006 (as further amended, modified,
substituted, extended, and renewed from time to time, collectively, the
“Financing Agreement”).

B. Pursuant to the Fifth Amendment and an Additional Borrower Joinder Supplement
dated as of March 31, 2006 executed in connection therewith, RADIX TECHNOLOGIES,
INC., a California corporation (“Radix” collectively with Argon, the “Original
Borrower”), was added under the Financing Agreement an Additional Borrower (as
defined in the Financing Agreement).

C. The Financing Agreement provides for some of the agreements between Original
Borrower and Lender with respect to the “Loans” (as defined in the Financing
Agreement), including a revolving credit facility in the maximum principal
amount of $40,000,000 and a letter of credit sub-limit of $15,000,000 as part of
that revolving credit facility.

D. Effective December 31, 2007, pursuant to that certain Certificate of
Ownership and Merger merging Radix Technologies, Inc. with and into Argon ST,
Inc. dated December 13, 2007 filed with the Secretary of State of the State of
Delaware, Radix was merged into Argon, with Argon remaining as the successor
corporation.

E. Argon has acquired Coherent (Argon and Coherent are hereinafter referred to
collectively as “Borrower”) and Coherent has executed an Additional Borrower
Joinder Supplement of even date herewith as an Additional Borrower.

F. Borrower has requested that Lender (a) consent to the acquisition of
Coherent, (b) modify certain terms of the letter of credit facility, (c) consent
to certain repurchases of stock by Argon; (d) extend the Revolving Credit
Expiration Date to February 28, 2010 (e) consent to reducing certain financial
reporting from quarterly to semi-annually.

G. Lender is willing to agree to Borrower’s request on the condition, among
others, that this Agreement be executed.

AGREEMENTS

NOW, THEREFORE, in consideration of the premises and for other good and valuable
consideration, receipt of which is hereby acknowledged, Borrower and Lender
agree as follows:

1. Borrower and Lender agree that the Recitals above are a part of this
Agreement. Unless otherwise expressly defined in this Agreement, terms defined
in the Financing Agreement shall have the same meaning under this Agreement.

2. Each Borrower represents and warrants to Lender as follows:

(a) It is a corporation or limited liability company duly organized, and validly
existing and in good standing under the laws of the state of its organization
and is duly qualified to do business as a foreign entity in good standing in
every other state wherein the conduct of its business or the ownership of its
property requires such qualification;

(b) It has the power and authority to execute and deliver this Agreement and
perform its obligations hereunder and has taken all necessary and appropriate
corporate/member action to authorize the execution, delivery and performance of
this Agreement;

(c) The Financing Agreement, as heretofore amended and as amended by this
Agreement, and each of the other Financing Documents remains in full force and
effect, and each constitutes the valid and legally binding obligation of
Borrower, enforceable in accordance with its terms;

(d) All of Borrower’s representations and warranties contained in the Financing
Agreement and the other Financing Documents are true and correct on and as of
the date of Borrower’s execution of this Agreement; and

(e) No Event of Default and no event which, with notice, lapse of time or both
would constitute an Event of Default, has occurred and is continuing under the
Financing Agreement or the other Financing Documents which has not been waived
in writing by Lender.

3. The Financing Agreement is hereby amended as follows:

(a) The definition of “Revolving Credit Expiration Date” in Section 1.1 (Certain
Defined Terms) is hereby deleted in its entirety and the following definition is
inserted in its place:

““Revolving Credit Expiration Date” means February 28, 2010.”

(b) Section 2.2.1 (Letters of Credit) is hereby deleted in its entirety and the
following section is inserted in its place:

“2.2.1 Letters of Credit.

Subject to and upon the provisions of this Agreement, and as a part of the
Revolving Credit Commitments, Borrower, upon the prior approval of Agent, may
obtain standby or commercial letters of credit (as the same may from time to
time be amended, supplemented or otherwise modified, each a “Letter of Credit”
and collectively the “Letters of Credit”) from Lender from time to time from the
Closing Date until the Business Day preceding the Revolving Credit Termination
Date. The Borrower will not be entitled to obtain a Letter of Credit hereunder
unless (a) after giving effect to the request, the outstanding principal balance
of the Revolving Loan and of the Letter of Credit Obligations would not exceed
the Revolving Credit Committed Amount (b) the sum of the aggregate face amount
of the then outstanding Letters of Credit (including the face amount of the
requested Letter of Credit) does not exceed Fifteen Million Dollars
($15,000,000) (the “Letter of Credit Sublimit”) and (c) the expiration date of
the requested Letter of Credit is not later than nine (9) months following the
Revolving Credit Expiration Date.”

(c) Section 6.1.15 (Financial Covenants) is hereby deleted in its entirety and
the following section is inserted in its place:

“6.1.15 Financial Covenant – Funded Debt to EBITDA.

The Borrower will maintain, on a consolidated basis and tested as of the last
day of each of the Borrower’s fiscal quarters for the four (4) quarter period
ending on that date, a ratio of Funded Debt to EBITDA equal to not more than
1.50 to 1.00.”

(d) Section 6.2.3 (Purchase or Redemption of Securities, Dividend Restrictions)
is deleted in its entirety and the following is inserted in its place:

“6.2.3 Purchase or Redemption of Securities, Dividend Restrictions.

Other than repurchases of up to 2,000,000 shares of its capital stock at a price
not to exceed $24 per share and in an aggregate amount not to exceed
$48,000,000, the Borrower will not purchase, redeem or otherwise acquire any
shares of its capital stock or warrants now or hereafter outstanding, declare or
pay any dividends thereon (other than stock dividends), apply any of its
property or assets to the purchase, redemption or other retirement of, set apart
any sum for the payment of any dividends on, or for the purchase, redemption, or
other retirement of, make any distribution by reduction of capital or otherwise
in respect of, any             shares of any class of capital stock of the
Borrower, or any warrants, permit any Subsidiary to purchase or acquire any
shares of any class of capital stock of, or warrants issued by, the Borrower,
make any distribution to stockholders or set aside any funds for any such
purpose, and not prepay, purchase or redeem any Funded Debt other than the
Obligations.”

(e) Section 6.1.1.(c) (Quarterly Statements Certificates) is deleted in its
entirety and the following is inserted in its place:

Semi-Annual Statements and Certificates. The Borrower shall furnish to the
Lender as soon as available, but in no event more than forty five (45) days
after the close of the Borrower’s second and fourth fiscal quarters,
consolidated and consolidating balance sheets of the Borrower and its
Subsidiaries as of the close of each such semi-annual period, consolidated and
consolidating income, cash flows and changes in shareholders equity statements
for such period and a Compliance Certificate, in substantially the form attached
to this Agreement as EXHIBIT B, containing a detailed computation of each
financial covenant which is applicable for the period reported, a certification
that no change has occurred to the information contained in the Collateral
Disclosure List (except as set forth on any schedule attached to the
certification), each prepared by a Responsible Officer of the Borrower in a
format acceptable to the Lender, all as prepared and certified by a Responsible
Officer of the Borrower and accompanied by a certificate of that officer stating
whether any event has occurred which constitutes a Default or an Event of
Default hereunder, and, if so, stating the facts with respect thereto.

(f) The Worksheet attached as Schedule I to Exhibit B (Financing Agreement
Compliance Certificate) is hereby deleted in its entirety and the worksheet form
attached hereto is inserted in its place.

4. Any provisions of Section 6.2.1 (Capital Structure, Merger, Acquisition of
Sale of Assets) to the contrary notwithstanding, the Lender hereby consents to
(i) the merger of Radix into Argon effective as of      , and (ii) the
acquisition by Argon of Coherent and consent to the payment of additional
consideration to the sellers of Coherent pursuant to the terms of the applicable
purchase agreement provided that at the time of payment of any such additional
consideration no default has occurred and is continuing under the Financing
Documents and provided no default will occur as a result of the payment of such
contingent payments. From and after the date hereof, the definition of
“Borrower” set forth in the Financing Agreement shall include Argon and Coherent
and each Additional Borrower hereafter accepted and approved by the Lender.

5. The agreements of the Lender under this Agreement are subject to the
following terms and conditions, time being of the essence:

(a) Execution and delivery by Coherent of a Collateral Disclosure List on
Lender’s form and in all respects satisfactory to Lender;

(b) Execution and delivery of an Additional Borrower Joinder Supplement by each
Borrower pursuant to which Coherent is added as a Borrower under the Financing
Agreement;

(c) Completion of UCC searches in all offices and under all names deemed
necessary by Lender and confirming Lender’s first perfected security interest in
the Collateral; and

(d) Delivery of updated versions of Schedules 4.1.10, 4.1.13 and 4.1.19 to be
attached hereto.

6. Each Borrower hereby issues, ratifies and confirms the representations,
warranties and covenants contained in the Financing Agreement, as amended
hereby. Each Borrower agrees that this Agreement is not intended to and shall
not cause a novation with respect to any or all of the Obligations.

7. Each Borrower acknowledges and warrants that Lender has acted in good faith
and has conducted in a commercially reasonable manner its relationships with
Borrower in connection with this Agreement and generally in connection with the
Financing Agreement and the Obligations, each Borrower hereby waiving and
releasing any claims to the contrary.

8. Borrower shall pay at the time this Agreement is executed and delivered all
fees, commissions, costs, charges, taxes and other expenses incurred by Lender
and its counsel in connection with this Agreement, including, but not limited
to, reasonable fees and expenses of Lender’s counsel and all recording fees,
taxes and charges.

9. This Agreement may be executed in any number of duplicate originals or
counterparts, each of such duplicate originals or counterparts shall be deemed
to be an original and all taken together shall constitute but one and the same
instrument. Borrower agrees that Lender may rely on a telecopy of any signature
of Borrower. Lender agrees that Borrower may rely on a telecopy of this
Agreement executed by Lender.

[SIGNATURES APPEAR ON THE FOLLOWING PAGE]

1

IN WITNESS WHEREOF, each Borrower and Lender have executed this Agreement under
seal as of the date and year first written above.

     
WITNESS OR ATTEST:
  ARGON ST, INC. successor to SensyTech, Inc., formerly
known as Sensys Technologies Inc.
/s/ Joseph T. Houston
  By: Aaron N. Daniels (Seal)
 
   
 
  Name: Aaron N. Daniels
Title: Vice President, Chief Financial Officer and
Treasurer

WITNESS: COHERENT SYSTEMS INTERNATIONAL, LLC

     
/s/ Joseph T. Houston
  By: Aaron N. Daniels (Seal)
 
   
 
  Name: Aaron N. Daniels
Title: Vice President, Chief Financial Officer and
Treasurer
WITNESS:
  BANK OF AMERICA, N. A.
     
  By:     (Seal)
Jessica Tencza
Senior Vice President

2

Schedule 2

No change has occurred to the information contained in the Collateral Disclosure
List except as set forth below:

3

LIST OF SCHEDULES

     
Schedule 4.1.10
  Litigation
 
 

Schedule 4.1.13
  Other Indebtedness
 
 

Schedule 4.1.19
  Permitted Liens
 
 

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Schedule 4.1.10

LITIGATION

On November 1, 2007, we filed suit in the Circuit Court of Fairfax County,
Virginia, against Optical Air Data Systems, LLC (“OADS”) seeking approximately
$642,000 in damages with respect to OADS’s failure to pay us for work performed
under a subcontract with OADS in 2004 and 2005.  In the afternoon of November 1,
2007, we were served with a complaint against us filed by OADS in the Circuit
Court of Prince William County, Virginia, alleging one count of breach of
contract and one count of breach of confidential disclosure agreement relating
to our work under the OADS subcontract, and alleging damages in excess of
$800 million.  We believe that both the claims and alleged damages in the OADS
suit are wholly without merit, and intend to vigorously defend against them
while pursuing its original claim for non-payment.

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Schedule 4.1.13

OTHER INDEBTEDNESS

None.

6

Schedule 4.1.19

LIENS ON COLLATERAL

Asset Covered Lienholder Balance

None.

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SCHEDULE 1

WORKSHEET

Funded Debt to EBITDA Argon ST, Inc.

   

Section 6.1.15 of Financing and Security Agreement — The Borrower will maintain,
tested as of the last day of each of the Borrower’s fiscal quarters for the
preceding four (4) fiscal quarters, a Funded Indebtedness to EBITDA Ratio of not
more than 1.50 to 1.00.

Section 1.1 of Financing and Security Agreement — “Funded Debt,” means all
outstanding liabilities for borrowed money and other interest-bearing
liabilities, including current and long-term debt, issued letters of credit,
Capitalized Leases and Subordinated Indebtedness.

Section 1.1 of Financing and Security Agreement — “EBITDA” means as to the
Borrower for any period of determination thereof, the sum of (a) the net profit
(or loss) determined in accordance with GAAP, plus (b) interest and taxes for
such period, plus (c) depreciation and amortization of assets for such period.

Amounts in Thousands

                                      Funded Debt
                               
 
  (i)   Debt for Borrowed money  
 
 
 
 
 
 
 
                                    (ii)   Debt evidenced by funds or notes and
other similar instruments              
               
 
  (iii)   Letters of Credit  
 
 
 
 
 
 
 
                                    (iv)   Debt consisting of Capital Lease
obligations                      
                            [v]   Subordinated Indebtedness                    
     
                                    Funded Debt               numerator       =
                                      (a)   (b)       (c )       [(b)-(a)]+(c)  
          PY Period   FYE   Current period        
 
          / /       / /           / /   Totals                          
Denominator
                               
(a)
      Net Income after tax  
 
 
 
 
 
 

 
         
 
 
 
 
 
 

(c)
      + Depreciation Expense  
 
 
 
 
 
 

 
         
 
 
 
 
 
 

(c)
      + Amortization Expense  
 
 
 
 
 
 

 
         
 
 
 
 
 
 

(d)
      + Interest Expense  
 
 
 
 
 
 

 
         
 
 
 
 
 
 

(e)
      + Income Taxes  
 
 
 
 
 
 

 
         
 
 
 
 
 
 
            EBITDA           denominator       =                          
Funded Debt to EBITDA                        
 
      Requirement (see above):  
 
 
 
 
 
 

 
      Pass/Fail:  
 
 
 
 
 
 

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