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                                                                Exhibit 10(m)




                      AMENDED AND RESTATED PROMISSORY NOTE

US $400,000                                          West Caldwell, New Jersey
                                                     July 29, 2002


                  FOR VALUE RECEIVED, MASON N. CARTER ("Payor"), hereby
unconditionally promises to pay, in accordance with the terms of this promissory
note (as the same may be amended from time to time, this "Promissory Note"), to
the order of MERRIMAC INDUSTRIES, INC., a Delaware corporation, or its
successors and assigns ("Note Holder"), in lawful money of the United States of
America in immediately available funds, on May 4, 2006 and in such account, at
such place, or to such party as Note Holder may designate in writing, the
principal amount of Four Hundred Thousand Dollars (US $400,000). Payor also
unconditionally promises to pay interest monthly in arrears from the date hereof
(as specified below) on the unpaid principal amount of this Promissory Note
outstanding from time to time at a rate calculated each 12-month period
beginning on the date hereof, which rate is based upon the weighted average of
the rates announced publicly from time to time during such period by Note
Holder's primary lending bank (currently, Fleet National Bank) as its prime
rate.

                  Payment of this Promissory Note is secured by the Pledged
Collateral (as defined in the Amended and Restated Pledge Agreement dated as of
the date hereof by Payor for the benefit of Note Holder (the "Pledge
Agreement")), including, without limitation, the Pledged Shares (as defined in
the Pledge Agreement) and any property or interest provided in addition to or in
substitution for any of the foregoing.

                  Payor may, at its option, prepay all or, from time to time,
any part of the unpaid principal balance of this Promissory Note, together with
interest accrued thereon, without payment of any premium or penalty.

                  Payor hereby waives presentment, demand, notice, protest and
all other demands and notices in connection with the delivery, acceptance,
performance, default or enforcement of this Promissory Note.

                  If Payor's employment with Note Holder is terminated pursuant
to Section 6(c) of the Amended and Restated Employment Agreement, dated January
1, 1998, between Payor and Note Holder, then Note Holder, at its


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option, by written notice to Payor, may declare the entire principal amount of
this Promissory Note to be due and payable, together with accrued interest
thereon, without other notice, demand, presentment or protest, all of which are
hereby waived by Payor.

                  Payor shall not assign this Promissory Note or its obligations
hereunder without the prior written consent of Note Holder. This Promissory Note
shall be binding upon Payor and its permitted assigns and shall inure to the
benefit of Note Holder and its successors and assigns.

                  This Promissory Note has been executed and delivered in the
State of New Jersey and shall be governed by, and construed and interpreted in
accordance with, the internal laws of the State of New Jersey without giving
effect to any conflicts of laws provisions of such State.


                                                      /s/ Mason N. Carter
                                                    ---------------------------
                                                          Mason N. Carter