SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* ISENSTEIN BARRY S (Last) (First) (Middle) 93 WOODBINE ROAD (Street) CARLISLE MA 01741 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol MERCURY COMPUTER SYSTEMS INC [ MRCY ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) VP Defense Electronics Group
	3. Date of Earliest Transaction (Month/Day/Year) 11/08/2005
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	11/08/2005		M		800	A	$7.625	28,868	I	By The Isenstein Family Investment Trust
Common Stock								8,334	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Exercise of Incentive Stock Option	$7.625	11/08/2005		M			800	09/28/2003	09/28/2008	Common	800	$0.00	0	D

Explanation of Responses:

	Craig Barrows, Attorney-in-fact	11/09/2005
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

LIMITED POWER OF ATTORNEY
FOR
MERCURY COMPUTER SYSTEMS, INC.
SECTION 16(a) FILINGS


        Know all by these presents, that the undersigned hereby constitutes and appoints each of
Robert E. Hult, Senior Vice-President and Chief Financial Officer, Alex Braverman, Vice-
President, Corporate Controller and Chief Accounting Officer, and Craig Barrows, Vice-
President, General Counsel and Assistant Secretary, acting singly, the undersigned's true and
lawful attorney-in-fact to:

(1)	execute for and on behalf of the undersigned, in the undersigned's capacity as an
officer, director and/or shareholder of Mercury Computer Systems, Inc. (the
"Company"), Forms 3, 4 and 5, and amendments thereto, in accordance with
Section 16(a) of the Securities Exchange Act of 1934, as amended (the "Exchange
Act") and the rules thereunder;

(2)	do and perform any and all acts for and on behalf of the undersigned which may
be necessary or desirable to complete and execute any such Form 3, 4 or 5, or
amendments thereto, and timely file such form with the United States Securities
and Exchange Commission (the "SEC") and any stock exchange or similar
authority; and

(3)	take any other action of any type whatsoever which, in the opinion of such
attorney-in-fact, may be necessary or desirable in connection with the foregoing
authority, it being understood that the documents executed by each such attorney-
in-fact on behalf of the undersigned pursuant to this Limited Power of Attorney
shall be in such form and shall contain such terms and conditions as such
attorney-in-fact may approve, provided, however, that the undersigned does not
grant to each such power-of-attorney the right to engage in any transactions
involving the securities of the Company on behalf of the undersigned, including
without limitation, the right to purchase or sell any securities of the Company.

        The undersigned hereby grants to each such attorney-in-fact full power and authority to
do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done
in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes
as the undersigned might or could do if personally present, with full power of substitution or
revocation, hereby ratifying and confirming all that each such attorney-in-fact, or each such
attorney-in-fact's substitute or substitutes (any such substitute also being referred to herein as an
"attorney-in-fact"), shall lawfully do or cause to be done by virtue of this Limited Power of
Attorney and the rights and powers herein granted.  The undersigned acknowledges that each
attorney-in-fact, in serving in such capacity at the request of the undersigned or such attorney-in-
fact, is not assuming, nor is the Company assuming, any of the undersigned's responsibilities to
comply with Section 16 of the Exchange Act.


        The undersigned agrees that each such attorney-in-fact shall not be liable for any error of
judgment or for any act done or omitted to be done or for any mistake of fact or law except for
each such attorney-in-fact's own bad faith, and the undersigned agrees to indemnify and to hold
each such attorney-in-fact harmless against any loss, claim, damage, liability or cost incurred on
each such attorney-in-fact's part arising out of or in connection with acts undertaken or omitted
to be taken as an attorney-in-fact hereunder.

        This Limited Power of Attorney shall remain in full force and effect until the undersigned
is no longer required to file Forms 3, 4, and 5 with respect to the undersigned's holdings of
and transactions in securities of the Company, unless earlier revoked by the undersigned in a
signed writing delivered to the foregoing attorneys-in-fact.  This Limited Power of Attorney may
be filed with the SEC as a confirming statement of the authority granted herein.

        IN WITNESS WHEREOF, the undersigned has caused this Limited Power of Attorney to
be executed as of this 20 day of October, 2005.


                                             /s/ Barry S. Isenstein






LIBC/1640386.1

2