EXHIBIT 10.21

                                 AMENDMENT NO. 2

                                       TO

                           LOAN AND SECURITY AGREEMENT

            THIS AMENDMENT NO. 2 ("Amendment") is entered into as of May 19,
1999, by and between MPD TECHNOLOGIES, INC., a New York corporation ("Borrower")
having its principal place of business at 49 Wireless Boulevard, Hauppauge, New
York and IBJ WHITEHALL BUSINESS CREDIT CORPORATION (formerly known as IBJ
Schroder Business Credit Corporation) ("IBJ") having its principal place of
business at One State Street, New York, New York and each of the other financial
institutions named in or which hereafter become a party to the Loan Agreement
(as defined below) (IBJ and such other financial institutions, the "Lenders")
and IBJ as agent for the Lenders (IBJ in such capacity, the "Agent").

                                   BACKGROUND

            Borrower, Agent and Lenders are parties to a Loan and Security
Agreement dated as of February 13, 1997 (as amended, supplemented or otherwise
modified from time to time, the "Loan Agreement") pursuant to which Lenders
provided Borrower with certain financial accommodations.

            Borrower has requested that Lenders and Agent amend the Loan
Agreement to, among other things, (a) increase the amount of the overall credit
facility by providing for an additional $3,000,000 equipment loan facility, (b)
increase the Maximum Revolving Amount, (c) decrease rates of interest and (d)
extend the termination date, and Agent and Lenders are willing to do so on the
terms and conditions hereafter set forth.

            NOW, THEREFORE, in consideration of any loan or advance or grant of
credit heretofore or hereafter made to or for the account of Borrower by Agent
and Lenders, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto hereby agree as
follows:

            1. Definitions. All capitalized terms not otherwise defined herein
shall have the meanings given to them in the Loan Agreement.

            2. Amendment to Loan Agreement. Subject to satisfaction of the
conditions precedent set forth in Section 3 below, the Loan Agreement is hereby
amended as follows:

            2.1. Section 1.2 of the Loan Agreement is hereby amended by
inserting the following defined terms in their appropriate alphabetical order:

            Additional Capex Loans - the loans made by Lenders as provided in
            Section 2.3(C) of this Agreement.

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            Additional Capex Note - the secured promissory note to be executed
            by Borrower to evidence the Capex Loans, which shall be in the form
            of Exhibit 2.3(C) attached to Amendment No. 2.

            Amendment No. 2 - means Amendment No. 2 to Loan and Security
            Agreement dated as of the Amendment No. 2 Effective Date among
            Borrower, Lenders and Agent.

            Amendment No. 2 Effective Date - means May 19, 1999.

            Maximum Additional Capex Amount -Three Million Dollars
            ($3,000,000), less principal payments of the Additional Capex
            Loans.

            2.2. Section 1.2 of the Loan Agreement is hereby amended by amending
the following defined terms in their entirety to provide as follows:

            Loans - all loans and advances made by Lenders pursuant to this
            Agreement, including, without limitation, all Revolving Credit
            Loans, Capex Loans, Additional Capex Loans and the Term Loan.

            Maximum Revolving Amount - Thirteen Million Seven Hundred Fifty
            Thousand ($13,750,000).

            Notes - the Term Note, the Capex Note, the Additional Capex Note and
the Revolving Credit Note.

            2.3 Section 1.1 of the Loan Agreement is hereby amended by amending
the definition of "Borrowing Base" by deleting "$6,000,000" in clause (b) (ii)
(a) and inserting "$7,000,000" in its place and stead.

            2.4 The preamble of Section 2 of the Loan Agreement is hereby
amended by deleting the phrase "FIFTEEN MILLION FOUR HUNDRED FIFTY THOUSAND AND
XX/100 DOLLARS ($15,450,000)" appearing in the fourth and fifth lines thereof
and replacing it with the phrase "TWENTY MILLION SIX HUNDRED SEVENTY SIX
THOUSAND FOUR HUNDRED AND XX/100 DOLLARS ($20,676,400)" in its place and stead.
2.5 Section 2.3 of the Loan Agreement is hereby amended by inserting a new
subsection "(C)" at the end thereof as follows:

            2.5 Section 2.3 of the Loan Agreement is hereby amended by inserting
a new subsection "(C)" at the end of thereof as follows:

                  "(C) Additional Capex Loans. (i) Subject to the terms and
            conditions set forth herein, each Lender, severally and not jointly,
            agrees to make Loans (in addition to the Capex Loans) to Borrower to
            finance Borrower's purchase of Equipment for use in Borrower's
            business ("Additional Capex Loans") in the sum equal to such
            Lender's Commitment Percentage of an amount not to exceed eighty

<PAGE>

            percent (80%) of the net invoice cost of such Equipment purchased by
            Borrower (which shall be exclusive of shipping, handling, taxes,
            installation and all other "soft" costs) provided that the total
            amount of all outstanding Additional Capex Loans shall not exceed
            the Maximum Additional Capex Amount. All Additional Capex Loans must
            be in original principal amounts of not less than $100,000.
            Additional Capex Loans may only be borrowed prior to the first
            anniversary of the Amendment No. 2 Effective Date. Once repaid, an
            Additional Capex Loan may not be reborrowed. The Additional Capex
            Loan shall be evidenced by and subject to the terms of a secured
            promissory note, in substantially the form attached hereto as
            Exhibit 2.3(C) (the "Capex Note").

                       (ii) Loans constituting Additional Capex Loans shall be
            accumulated during each of twelve periods (each a "Borrowing
            Period") during the Term. Each Additional Borrowing Period shall
            consist of one month with the first Additional Borrowing Period
            commencing on the Amendment No. 2 Effective Date and ending on June
            18, 1999. At the end of each Borrowing Period, the sum of the
            principal amount of all Additional Capex Loans made during such
            Additional Borrowing Period will be amortized on the basis of a
            sixty (60) month amortization schedule (such amount as determined
            with respect to any Additional Borrowing Period, the " Additional
            Amortization Amount"). Monthly principal payments will be initially
            determined for the Additional Capex Loans made during the initial
            Additional Borrowing Period and the amount of such monthly principal
            payments shall be increased upon the completion of each subsequent
            Additional Borrowing Period by the Additional Amortization Amount
            for each such subsequent Additional Borrowing Period. Each
            Additional Capex Loan shall be, with respect to principal, payable
            in equal monthly installments based upon the amortization schedule
            set forth above, commencing on the first Business Day of the month
            following the month in which such Additional Capex Loan was made and
            on the first day of each month thereafter, subject to acceleration
            upon the occurrence and continuance of an Event of Default under
            this Agreement or termination of this Agreement. Each Lender's
            Commitment Percentage of the Additional Capex Loans shall be
            evidenced by and subject to the Additional Capex Note."

            2.6 Section 2.16(A) of the Loan Agreement is hereby amended by
inserting the following sentence at the end thereof:

            "The Additional Capex Loans shall be advanced according to the
            Commitment Percentages of Lenders."

            2.7 Section 2.16(B) of the Loan Agreement is hereby amended by
adding the following sentence immediately after the third sentence thereof:

            "Each payment (including each prepayment) by Borrower on account of
            the

<PAGE>

            principal of and interest on the Additional Capex Note, shall be
            made from or to, or applied to that portion of the Additional Capex
            Loans evidenced by the Additional Capex Note pro rata according to
            the Commitment Percentages of Lenders."

            2.8. Section 3.1(A) of the Loan Agreement is hereby amended by (i)
inserting the phrase "plus the Additional Capex Loans" immediately after the
phrase "the Term Loan" appearing in the third line thereof; (ii) deleting the
reference in clause (a) to "Alternate Base Rate plus three-quarters of one
percent (.75%)" and inserting "Alternate Base Rate plus one-quarter of one
percent (.25%)" in its place and stead and (iii) deleting the reference in
clause (b) to "Alternate Base Rate plus one-half of one percent (.50%)" and
inserting "Alternate Base Rate" in its place and stead.

            2.9. Section 3.1(D) of the Loan Agreement is hereby amended by
deleting the first sentence in its entirety and replacing it with the following
in its place and stead:

            "Borrower shall pay an unused facility fee at the rate of
            one-quarter of one percent (1/4%) per annum on the difference
            between (a) (i) the Maximum Revolving Amount plus (ii) the unpaid
            balance of the Capex Loans plus (iii) from May 19, 1999 through May
            19, 2000, the Maximum Additional Capex Amount or, at any time
            thereafter, the unpaid balance of the Additional Capex Loans and (b)
            the average daily unpaid balance of the Loans (other than the Term
            Loan), payable to Agent for the ratable benefit of Lenders quarterly
            in arrears, commencing on the first day of the calendar quarter
            following the calendar quarter in which the Closing Date occurs."

            2.10. Section 3.2 of the Loan Agreement is hereby amended by
deleting the phrase "February 12, 2001" appearing in the fourth and fifth lines
thereof and replacing it with the phrase "February 12, 2002" in its place and
stead.

            2.11. Section 3.3(C) of the Loan Agreement is hereby amended by (i)
inserting the phrase "plus the Maximum Additional Capex Amount" immediately
after the phrase "the Maximum Revolving Amount" appearing in the eighth and
twelfth lines thereof, (ii) deleting the references in clause (a) and (y) to
"Closing Date" and inserting "Amendment No. 1 Effective Date" in their place and
stead.

            2.12. Section 3.3(D) of the Loan Agreement is hereby amended by
inserting the phrase "and the Additional Capex Loans" immediately following the
phrase "the Term Loan" appearing in the second sentence thereof.

            2.13. Section 3.5 of the Loan Agreement is hereby amended by
inserting the phrase "and/or the Additional Capex Loans" immediately after the
phrase "the Term Loan" appearing in the sixteenth line thereof.

            2.14. Section 10 of the Loan Agreement is hereby amended to include
the following new subsection 10.4 at the end thereof:

<PAGE>

                 "10.4. Conditions to Each Additional Capex Loan. The agreement
            of Lenders to make any Additional Capex Loan is subject to
            satisfaction of the following conditions precedent: (a) receipt by
            Agent of (i) a copy of the invoice relating to the Equipment being
            purchased, (ii) evidence that such Equipment has been shipped to
            Borrower, (iii) evidence that the requested Additional Capex Loan
            does not exceed eighty percent (80%) of the net invoice cost of such
            Equipment purchased by Borrower (which shall be exclusive of
            shipping, handling, taxes, installation and all other "soft" costs),
            and (iv) such other documentation and evidence that Agent may
            request; (b) no breach of Section 9.3 of the Loan Agreement shall
            exist for the most recent completed fiscal quarter with compliance
            tested as if the requested Additional Capex Loan was outstanding on
            the first day of such fiscal quarter; and (c) after giving effect
            thereto, the aggregate outstanding Additional Capex Loans shall not
            exceed the Maximum Additional Capex Amount."

            2.15. Section 13.12 of the Loan Agreement is hereby amended to by
inserting the phrase "and the Additional Capex Loans" immediately after the
phrase "Revolving Credit Loan" appearing in the last line thereof.

            2.16. Exhibit 2.1 to the Loan Agreement (as amended by Amendment
No. 1) is hereby deleted and replaced in its entirety with Exhibit 2.1
attached to Amendment No. 2.

            3. Conditions of Effectiveness. This Amendment shall become
effective upon satisfaction of the following conditions precedent: Agent shall
have received (i) four (4) copies of this Amendment executed by Borrower and
consented and agreed to by Microwave Power Devices, Inc., as guarantor, (ii) an
amendment fee to Agent equal to $27,500, (iii) an executed Second Amended and
Restated Revolving Credit Note, (iv) an executed Additional Capex Note and (v)
evidence in the form of corporate resolutions demonstrating that Borrower shall
have taken all necessary corporate action for the authorization, execution,
delivery and performance of this amendment and (vi) such other certificates,
instruments, documents, agreements and opinions of counsel as may be required by
Agent or its counsel, each of which shall be in form and substance satisfactory
to Agent and its counsel.

            4. Representations and Warranties. Borrower hereby represents and
warrants as follows:

                  (a) This Amendment and the Loan Agreement, as amended hereby,
            constitute legal, valid and binding obligations of Borrower and are
            enforceable against Borrower in accordance with their respective
            terms.

                  (b) Upon the effectiveness of this Amendment, Borrower hereby
            reaffirms all covenants, representations and warranties made in the
            Loan Agreement to the extent the same are not amended hereby and
            agree that all such covenants, representations and warranties shall
            be deemed to have been remade as of the effective date of this
            Amendment.

<PAGE>

                  (c) No Event of Default or Default has occurred and is
            continuing or would exist after giving effect to this Amendment.

                  (d) Borrower has no defense, counterclaim or offset with
            respect to the Loan Agreement.

            5. Effect on the Loan Agreement.

            (a) Upon the effectiveness of this Amendment, each reference in the
Loan Agreement to "this Agreement," "hereunder," "hereof," "herein" or words of
like import shall mean and be a reference to the Loan Agreement as amended
hereby.

            (b) Except as specifically amended herein, the Loan Agreement, and
all other documents, instruments and agreements executed and/or delivered in
connection therewith, shall remain in full force and effect, and are hereby
ratified and confirmed.

            (c) The execution, delivery and effectiveness of this Amendment
shall not operate as a waiver of any right, power or remedy of Agent, nor
constitute a waiver of any provision of the Loan Agreement, or any other
documents, instruments or agreements executed and/or delivered under or in
connection therewith.

            6. Governing Law. This Amendment shall be binding upon and inure to
the benefit of the parties hereto and their respective successors and assigns
and shall be governed by and construed in accordance with the laws of the State
of New York.

            7. Headings. Section headings in this Amendment are included herein
for convenience of reference only and shall not constitute a part of this
Amendment for any other purpose.

            8. Counterparts; Telecopied Signatures. This Amendment may be
executed in any number of and by different parties hereto on separate
counterparts, all of which, when so executed, shall be deemed an original, but
all such counterparts shall constitute one and the same agreement. Any signature
delivered by a party by facsimile transmission shall be deemed to be an original
signature hereto.

<PAGE>

            IN WITNESS WHEREOF, this Amendment has been duly executed as of the
day and year first written above.

                                    MPD TECHNOLOGIES, INC.

                                    By: /s/ Paul E. Donofrio
                                        --------------------
                                    Name: Paul E. Donofrio
                                    Title: Executive Vice President, Chief
                                             Operating and Financial Officer


                                    IBJ WHITEHALL BUSINESS CREDIT
                                    CORPORATION, as Agent and a Lender

                                    By: /s/ Edward A. Jesser
                                        --------------------
                                    Name: Edward A. Jesser
                                    Title: SVP

CONSENTED AND AGREED TO:

MICROWAVE POWER DEVICES, INC.


By: /s/ Paul E. Donofrio
    --------------------
Name: Paul E. Donofrio
Title: Executive Vice President, Chief Operating
         and Financial Officer

<PAGE>

                                   EXHIBIT 2.1

                           SECOND AMENDED AND RESTATED
                              REVOLVING CREDIT NOTE

$13,750,000.00                                              New York, New York
                                                            as of May 19, 1999

            This Second Amended and Restated Revolving Credit Note is executed
and delivered under and pursuant to the terms of that certain Loan and Security
Agreement dated as of February 13, 1997 (as the same has been and may be further
amended, supplemented or modified from time to time, the "Loan Agreement") by
and among MPD TECHNOLOGIES, INC., a New York corporation having its chief
executive office at 49 Wireless Boulevard, Hauppauge, New York 11788
("Borrower"), IBJ WHITEHALL BUSINESS CREDIT CORPORATION (formerly known as IBJ
Schroder Business Credit Corporation) ("IBJ"), each of the other financial
institutions named in or which hereafter become parties to the Loan Agreement
(IBJ and such other financial institutions, the "Lenders") and IBJ as agent for
the Lenders (IBJ in such capacity, "Agent"). Capitalized terms not otherwise
defined herein shall have the meanings as provided in the Loan Agreement.

            FOR VALUE RECEIVED, Borrower hereby promises to pay to the order of
Agent for the ratable benefit of Lenders at Agent's offices located at One State
Street, New York, New York 10004 or at such other place as Agent may from time
to time designate in writing to Borrower:

            (i) the principal sum of THIRTEEN MILLION SEVEN HUNDRED FIFTY
THOUSAND AND 00/100 DOLLARS ($13,750,000.00) or, if different from such amount,
such amount of Revolving Advances as may be due and owing under the Loan
Agreement, payable in accordance with the provisions of the Loan Agreement and
subject to acceleration upon the occurrence of an Event of Default under the
Loan Agreement, earlier termination of the Loan Agreement or earlier prepayment
as required pursuant to the terms thereof; and

            (ii) interest on the principal amount of this Note from time to time
outstanding until such principal amount is paid in full, at such interest rates
and at such times as are provided in the Loan Agreement. Upon and after the
occurrence of an Event of Default, and during the continuation thereof, interest
shall be payable at the Default Rate. In no event, however, shall interest
hereunder exceed the maximum interest rate permitted by law.

            This Second Amended and Restated Revolving Credit Note amends and
restates in its entirety and is given in substitution for, but not in
satisfaction of, that certain Amended and Restated Revolving Credit Note dated
as of February 13, 1998 issued by Borrower in favor of Agent for the ratable
benefit of Lenders in the original principal amount of $12,000,000.

            This Note is the Revolving Credit Note referred to in the Loan
Agreement and is

<PAGE>

secured, inter alia, by the liens granted pursuant to the Loan Agreement and the
Other Agreements, is entitled to the benefits of the Loan Agreement and the
Other Agreements and is subject to all of the agreements, terms and conditions
therein contained.

            This Note is subject to mandatory prepayment and may be voluntarily
prepaid, in whole or in part, on the terms and conditions set forth in the Loan
Agreement.

            If an Event of Default under Sections 11.1(J) or 11.1(K) of the Loan
Agreement shall occur, then this Note shall immediately become due and payable,
without notice, together with reasonable attorneys' fees if the collection
hereof is placed in the hands of an attorney to obtain or enforce payment
hereof. If any other Event of Default shall occur under the Loan Agreement or
any of the Other Agreements which is not cured within any applicable grace
period, then this Note may, as provided in the Loan Agreement, be declared to be
immediately due and payable, without notice, together with reasonable attorneys'
fees, if the collection hereof is placed in the hands of an attorney to obtain
or enforce payment hereof.

            This Note is being delivered in the State of New York, and shall be
construed and enforced in accordance with the laws of such State.

            Borrower expressly waives any presentment, demand, protest, notice
of protest, or notice of any kind except as expressly provided in the Loan
Agreement.

                                    MPD TECHNOLOGIES, INC.


                                    By: /s/ Paul E. Donofrio
                                        --------------------
                                    Name: Paul E. Donofrio
                                    Title: Executive Vice President, Chief
                                             Operating and Financial Officer

STATE OF NEW YORK       )
                        : ss.:
COUNTY OF NEW YORK      )

            On the 20 day of May, 1999, before me personally came Paul E.
Donofrio, to me known, who being by me duly sworn, did depose and say that he is
the Executive Vice President, Chief Operating and Financial Officer of MPD
Technologies, Inc., the corporation described in and which executed the
foregoing instrument; and that he was authorized to sign his name thereto.

                                          /s/ Concetta Ombrellino
                                          -----------------------
                                          Notary Public, State of New York
                                          Suffolk County No. 01OM6015966
                                          Commission Expires November 09, 2000

<PAGE>

                                 EXHIBIT 2.3(C)

                              ADDITIONAL CAPEX NOTE

$3,000,000.00                                          New York, New York
                                                       as of May 19, 1999

            This Additional Capex Note is executed and delivered under and
pursuant to the terms of that certain Loan and Security Agreement dated as of
February 13, 1997 (as the same has been and may be further amended, supplemented
or modified from time to time, the "Loan Agreement") by and among MPD
TECHNOLOGIES, INC., a New York corporation having its chief executive office at
49 Wireless Boulevard, Hauppauge, New York 11788 ("Borrower"), IBJ WHITEHALL
BUSINESS CREDIT CORPORATION (formerly known as IBJ Schroder Business Credit
Corporation) ("IBJ"), each of the other financial institutions named in or which
hereafter become parties to the Loan Agreement (IBJ and such other financial
institutions, the "Lenders") and IBJ as agent for the Lenders (IBJ in such
capacity, "Agent"). Capitalized terms not otherwise defined herein shall have
the meanings as provided in the Loan Agreement.

            FOR VALUE RECEIVED, Borrower hereby promises to pay to the order of
Agent for the ratable benefit of Lenders at Agent's offices located at One State
Street, New York, New York 10004 or at such other place as Agent may from time
to time designate to Borrower in writing:

            (i) the principal sum of THREE MILLION AND 00/100 DOLLARS
($3,000,000.00) or such lesser amount as shall be advanced by Lender on or
before May 19, 2000, payable in consecutive monthly installments each in an
amount equal to the applicable monthly payment on Additional Capex Loans as set
forth in the Loan Agreement, subject to acceleration upon the occurrence of an
Event of Default under the Loan Agreement, earlier termination of the Loan
Agreement or earlier prepayment as required pursuant to the terms of the Loan
Agreement; and

            (ii) interest on the principal amount of this Note from time to time
outstanding until such principal amount is paid in full, at such interest rates
and at such times as are provided in the Loan Agreement. Upon and after the
occurrence of an Event of Default, and during the continuation thereof, interest
shall be payable at the Default Rate. In no event, however, shall interest
hereunder exceed the maximum interest rate permitted by law.

            This Note is the Additional Capex Note referred to in the Loan
Agreement and is secured, inter alia, by the liens granted pursuant to the Loan
Agreement and the Other Agreements, is entitled to the benefits of the Loan
Agreement and the Other Agreements and is subject to all of the agreements,
terms and conditions therein contained.

            This Note is subject to mandatory prepayment and may be voluntarily
prepaid, in whole or in part, on the terms and conditions set forth in the Loan
Agreement.

<PAGE>

            If an Event of Default under Sections 11.1(J) or 11.1(K) of the Loan
Agreement shall occur, then this Note shall immediately become due and payable,
without notice, together with reasonable attorneys' fees if the collection
hereof is placed in the hands of an attorney to obtain or enforce payment
hereof. If any other Event of Default shall occur under the Loan Agreement or
any of the Other Agreements, which is not cured within any applicable grace
period, then this Note may, as provided in the Loan Agreement, be declared to be
immediately due and payable, without notice, together with reasonable attorneys'
fees, if the collection hereof is placed in the hands of an attorney to obtain
or enforce payment hereof.

            This Note is being delivered in the State of New York, and shall be
construed and enforced in accordance with the laws of such State.

            Borrower expressly waives any presentment, demand, protest, notice
of protest, or notice of any kind except as expressly provided in the Loan
Agreement.

                                    MPD TECHNOLOGIES, INC.


                                    By: /s/ Paul E. Donofrio
                                        --------------------
                                    Name: Paul E. Donofrio
                                    Title: Executive Vice President, Chief
                                             Operating and Financial Officer

STATE OF NEW YORK       )
                        : ss.:
COUNTY OF NEW YORK      )

            On the 20 day of May, 1999, before me personally came Paul E.
Donofrio, to me known, who being by me duly sworn, did depose and say that he is
the Executive Vice President, Chief Operating and Financial Officer of MPD
Technologies, Inc., the corporation described in and which executed the
foregoing instrument; and that he signed his name thereto by order of the board
of directors of said corporation.


                                          /s/ Concetta Ombrellino
                                          -----------------------
                                          Notary Public, State of New York
                                          Suffolk County No. 01OM6015966
                                          Commission Expires November 09, 2000