<PAGE>

                     SUPPLEMENTAL INDENTURE TO BE DELIVERED
                          BY GUARANTEEING SUBSIDIARIES

     Supplemental Indenture (this "Supplemental Indenture"), dated as of
November 9, 2001, among Coleman Research Corporation, a Florida corporation, EER
Systems, Inc., a Virginia corporation, Electrodynamics, Inc., an Arizona
corporation, Henschel Inc., a Delaware corporation, Hygienetics Environmental
Services, Inc., a Delaware corporation, Interstate Electronics Corporation, a
California corporation, KDI Precision Products, Inc., a Delaware corporation,
L-3 Communications Aydin Corporation, a Delaware corporation, L-3 Communications
DBS Microwave, Inc., a California corporation, L-3 Communications ESSCO, Inc., a
Delaware corporation, L-3 Communications ILEX Systems, Inc., a Delaware
corporation, L-3 Communications SPD Technologies, Inc., a Delaware corporation,
L-3 Communications Storm Control Systems, Inc., a California corporation,
Microdyne Corporation, a Maryland corporation, MPRI, Inc., a Delaware
corporation, Pac Ord Inc., a Delaware corporation, Power Paragon, Inc., a
Delaware corporation, Southern California Microwave, Inc., a California
corporation, SPD Electrical Systems, Inc., a Delaware corporation, SPD Holdings,
Inc., a Delaware corporation and SPD Switchgear Inc., a Delaware
corporation(each, a "Guaranteeing Subsidiary," and collectively, the
"Guaranteeing Subsidiaries"), each a subsidiary of L-3 Communications
Corporation (or its permitted successor), a Delaware corporation (the
"Company"), the Company, and The Bank of New York, as trustee under the
indenture referred to below (the "Trustee").

                            W I T N E S S E T H

     WHEREAS, the Company has heretofore executed and delivered to the Trustee
an indenture (the "Indenture"), dated as of April 30, 1997 providing for the
issuance of an aggregate principal amount of up to $225,000,000 of 10 3/8%
Senior Notes due 2007 (the "Notes");

     WHEREAS, the Indenture provides that under certain circumstances the
Guaranteeing Subsidiaries shall execute and deliver to the Trustee a
supplemental indenture pursuant to which the Guaranteeing Subsidiaries shall
unconditionally guarantee all of the Company"s obligations under the Notes and
the Indenture on the terms and conditions set forth herein (the "Subsidiary
Guarantee"); and

     WHEREAS, pursuant to Section 4.13 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture.

     NOW THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the
Guaranteeing Subsidiaries and the Trustee mutually covenant and agree for the
equal and ratable benefit of the Holders of the Notes as follows:

     1. CAPITALIZED TERMS. Capitalized terms used herein without definition
shall have the meanings assigned to them in the Indenture.

     2. AGREEMENT TO GUARANTEE. Each Guaranteeing Subsidiary hereby agrees as
follows:

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                                                                               2

     (a)  Such Guaranteeing Subsidiary, jointly and severally with all other
          current and future guarantors of the Notes (collectively, the
          "Guarantors" and each, a "Guarantor"), unconditionally guarantees to
          each Holder of a Note authenticated and delivered by the Trustee and
          to the Trustee and its successors and assigns, regardless of the
          validity and enforceability of the Indenture, the Notes or the
          Obligations of the Company under the Indenture or the Notes, that:

          (i)  the principal of, premium and interest on the Notes will be
               promptly paid in full when due, whether at maturity, by
               acceleration, redemption or otherwise, and interest on the
               overdue principal of, premium and interest on the Notes, to the
               extent lawful, and all other obligations of the Company to the
               Holders or the Trustee thereunder or under the Indenture will be
               promptly paid in full, all in accordance with the terms thereof;
               and

          (ii) in case of any extension of time for payment or renewal of any
               Notes or any of such other obligations, that the same will be
               promptly paid in full when due in accordance with the terms of
               the extension or renewal, whether at stated maturity, by
               acceleration or otherwise.

     (b)  Notwithstanding the foregoing, in the event that this Subsidiary
          Guarantee would constitute or result in a violation of any applicable
          fraudulent conveyance or similar law of any relevant jurisdiction, the
          liability of such Guaranteeing Subsidiary under this Supplemental
          Indenture and its Subsidiary Guarantee shall be reduced to the maximum
          amount permissible under such fraudulent conveyance or similar law.

     3.   EXECUTION AND DELIVERY OF SUBSIDIARY GUARANTEES.

     (a)  To evidence its Subsidiary Guarantee set forth in this Supplemental
          Indenture, such Guaranteeing Subsidiary hereby agrees that a notation
          of such Subsidiary Guarantee substantially in the form of Exhibit F to
          the Indenture shall be endorsed by an officer of such Guaranteeing
          Subsidiary on each Note authenticated and delivered by the Trustee
          after the date hereof.

     (b)  Notwithstanding the foregoing, such Guaranteeing Subsidiary hereby
          agrees that its Subsidiary Guarantee set forth herein shall remain in
          full force and effect notwithstanding any failure to endorse on each
          Note a notation of such Subsidiary Guarantee.

     (c)  If an Officer whose signature is on this Supplemental Indenture or on
          the Subsidiary Guarantee no longer holds that office at the time the
          Trustee authenticates the Note on which a Subsidiary Guarantee is
          endorsed, the Subsidiary Guarantee shall be valid nevertheless.


<PAGE>
                                                                               3

     (d)  The delivery of any Note by the Trustee, after the authentication
          thereof under the Indenture, shall constitute due delivery of the
          Subsidiary Guarantee set forth in this Supplemental Indenture on
          behalf of each Guaranteeing Subsidiary.

     (e)  Each Guaranteeing Subsidiary hereby agrees that its obligations
          hereunder shall be unconditional, regardless of the validity,
          regularity or enforceability of the Notes or the Indenture, the
          absence of any action to enforce the same, any waiver or consent by
          any Holder of the Notes with respect to any provisions hereof or
          thereof, the recovery of any judgment against the Company, any action
          to enforce the same or any other circumstance which might otherwise
          constitute a legal or equitable discharge or defense of a guarantor.

     (f)  Each Guaranteeing Subsidiary hereby waives diligence, presentment,
          demand of payment, filing of claims with a court in the event of
          insolvency or bankruptcy of the Company, any right to require a
          proceeding first against the Company, protest, notice and all demands
          whatsoever and covenants that its Subsidiary Guarantee made pursuant
          to this Supplemental indenture will not be discharged except by
          complete performance of the obligations contained in the Notes and the
          Indenture.

     (g)  If any Holder or the Trustee is required by any court or otherwise to
          return to the Company or any Guaranteeing Subsidiary, or any
          Custodian, Trustee, liquidator or other similar official acting in
          relation to either the Company or such Guaranteeing Subsidiary, any
          amount paid by either to the Trustee or such Holder, the Subsidiary
          Guarantee made pursuant to this Supplemental Indenture, to the extent
          theretofore discharged, shall be reinstated in full force and effect.

     (h)  Each Guaranteeing Subsidiary agrees that it shall not be entitled to
          any right of subrogation in relation to the Holders in respect of any
          obligations guaranteed hereby until payment in full of all obligations
          guaranteed hereby. Each Guaranteeing Subsidiary further agrees that,
          as between such Guaranteeing Subsidiary, on the one hand, and the
          Holders and the Trustee, on the other hand:

          (i)  the maturity of the obligations guaranteed hereby may be
               accelerated as provided in Article 6 of the Indenture for the
               purposes of the Subsidiary Guarantee made pursuant to this
               Supplemental Indenture, notwithstanding any stay, injunction or
               other prohibition preventing such acceleration in respect of the
               obligations guaranteed hereby; and

          (ii) in the event of any declaration of acceleration of such
               obligations as provided in Article 6 of the Indenture, such
               obligations (whether or not due and payable) shall forthwith
               become due and payable by

<PAGE>
                                                                               4

               such Guaranteeing Subsidiary for the purpose of the Subsidiary
               Guarantee made pursuant to this Supplemental Indenture.

          (i)  Each Guaranteeing Subsidiary shall have the right to seek
               contribution from any other non-paying Guaranteeing Subsidiary so
               long as the exercise of such right does not impair the rights of
               the Holders or the Trustee under the Subsidiary Guarantee made
               pursuant to this Supplemental Indenture.

     4.   GUARANTEEING SUBSIDIARY MAY CONSOLIDATE, ETC. ON CERTAIN TERMS.

     (a)  Except as set forth in Articles 4 and 5 of the Indenture, nothing
          contained in the Indenture, this Supplemental Indenture or in the
          Notes shall prevent any consolidation or merger of any Guaranteeing
          Subsidiary with or into the Company or any other Guarantor or shall
          prevent any transfer, sale or conveyance of the property of any
          Guaranteeing Subsidiary as an entirety or substantially as an
          entirety, to the Company or any other Guarantor.

     (b)  Except as set forth in Article 4 of the Indenture, nothing contained
          in the Indenture, this Supplemental Indenture or in the Notes shall
          prevent any consolidation or merger of any Guaranteeing Subsidiary
          with or into a corporation or corporations other than the Company or
          any other Guarantor (in each case, whether or not affiliated with the
          Guaranteeing Subsidiary), or successive consolidations or mergers in
          which a Guaranteeing Subsidiary or its successor or successors shall
          be a party or parties, or shall prevent any sale or conveyance of the
          property of any Guaranteeing Subsidiary as an entirety or
          substantially as an entirety, to a corporation other than the Company
          or any other Guarantor (in each case, whether or not affiliated with
          the Guaranteeing Subsidiary) authorized to acquire and operate the
          same; provided, however, that each Guaranteeing Subsidiary hereby
          covenants and agrees that (i) subject to the Indenture, upon any such
          consolidation, merger, sale or conveyance, the due and punctual
          performance and observance of all of the covenants and conditions of
          the Indenture and this Supplemental Indenture to be performed by such
          Guaranteeing Subsidiaries, shall be expressly assumed (in the event
          that the Guaranteeing Subsidiaries are not the surviving corporations
          in the merger), by supplemental indenture satisfactory in form to the
          Trustee, executed and delivered to the Trustee, by the corporation
          formed by such consolidation, or into which such Guaranteeing
          Subsidiary shall have been merged, or by the corporation which shall
          have acquired such property and (ii) immediately after giving effect
          to such consolidation, merger, sale or conveyance no Default or Event
          of Default exists.

     (c)  In case of any such consolidation, merger, sale or conveyance and upon
          the assumption by the successor corporation, by supplemental
          indenture,

<PAGE>
                                                                               5

          executed and delivered to the Trustee and satisfactory in form to the
          Trustee, of the Subsidiary Guarantee made pursuant to this
          Supplemental Indenture and the due and punctual performance of all of
          the covenants and conditions of the Indenture and this Supplemental
          Indenture to be performed by each Guaranteeing Subsidiary, such
          successor corporation shall succeed to and be substituted for the
          Guaranteeing Subsidiary with the same effect as if it had been named
          herein as the Guaranteeing Subsidiary; provided that, solely for
          purposes of computing Consolidated Net Income for purposes of clause
          (b) of the first paragraph of Section 4.07 in the Indenture, the
          Consolidated Net Income of any Person other than Central Tractor Farm
          & Country, Inc. and its Restricted Subsidiaries shall only be included
          for periods subsequent to the effective time of such merger,
          consolidation, combination or transfer of assets. Such successor
          corporation thereupon may cause to be signed any or all of the
          Subsidiary Guarantees to be endorsed upon the Notes issuable under the
          Indenture which theretofore shall not have been signed by the Company
          and delivered to the Trustee. All the Subsidiary Guarantees so issued
          shall in all respects have the same legal rank and benefit under the
          Indenture and this Supplemental Indenture as the Subsidiary Guarantees
          theretofore and thereafter issued in accordance with the terms of the
          Indenture and this Supplemental Indenture as though all of such
          Subsidiary Guarantees had been issued at the date of the execution
          hereof.

     5.   RELEASES.

     (a)  Concurrently with any sale of assets (including, if applicable, all of
          the Capital Stock of a Guaranteeing Subsidiary), all Liens, if any, in
          favor of the Trustee in the assets sold thereby shall be released;
          provided that in the event of an Asset Sale, the Net Proceeds from
          such sale or other disposition are treated in accordance with the
          provisions of Section 4.10 of the Indenture. If the assets sold in
          such sale or other disposition include all or substantially all of the
          assets of a Guaranteeing Subsidiary or all of the Capital Stock of a
          Guaranteeing Subsidiary, then the Guaranteeing Subsidiary (in the
          event of a sale or other disposition of all of the Capital Stock of
          such Guaranteeing Subsidiary) or the Person acquiring the property (in
          the event of a sale or other disposition of all or substantially all
          of the assets of such Guaranteeing Subsidiary) shall be released from
          and relieved of its obligations under this Supplemental Indenture and
          its Subsidiary Guarantee made pursuant hereto; provided that in the
          event of an Asset Sale, the Net Proceeds from such sale or other
          disposition are treated in accordance with the provisions of Section
          4.10 of the Indenture. Upon delivery by the Company to the Trustee of
          an Officers" Certificate to the effect that such sale or other
          disposition was made by the Company or the Guaranteeing Subsidiary, as
          the case may be, in accordance with the provisions of the Indenture
          and this Supplemental Indenture, including without limitation, Section
          4.10 of the Indenture, the Trustee shall execute any documents
          reasonably required in order to evidence the release of the


<PAGE>
                                                                               6

          Guaranteeing Subsidiary from its obligations under this Supplemental
          Indenture and its Subsidiary Guarantee made pursuant hereto. If the
          Guaranteeing Subsidiary is not released from its obligations under its
          Subsidiary Guarantee, it shall remain liable for the full amount of
          principal of and interest on the Notes and for the other obligations
          of such Guaranteeing Subsidiary under the Indenture as provided in
          this Supplemental Indenture.

     (b)  Upon the designation of a Guaranteeing Subsidiary as an Unrestricted
          Subsidiary in accordance with the terms of the Indenture, such
          Guaranteeing Subsidiary shall be released and relieved of its
          obligations under its Subsidiary Guarantee and this Supplemental
          Indenture. Upon delivery by the Company to the Trustee of an Officers"
          Certificate and an Opinion of Counsel to the effect that such
          designation of such Guaranteeing Subsidiary as an Unrestricted
          Subsidiary was made by the Company in accordance with the provisions
          of the Indenture, including without limitation Section 4.07 of the
          Indenture, the Trustee shall execute any documents reasonably required
          in order to evidence the release of such Guaranteeing Subsidiary from
          its obligations under its Subsidiary Guarantee. Any Guaranteeing
          Subsidiary not released from its obligations under its Subsidiary
          Guarantee shall remain liable for the full amount of principal of and
          interest on the Notes and for the other obligations of any
          Guaranteeing Subsidiary under the Indenture as provided herein.

     6. NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator, stockholder or agent of any Guaranteeing
Subsidiary, as such, shall have any liability for any obligations of the Company
or any Guaranteeing Subsidiary under the Notes, any Subsidiary Guarantees, the
Indenture or this Supplemental Indenture or for any claim based on, in respect
of, or by reason of, such obligations or their creation. Each Holder of the
Notes by accepting a Note waives and releases all such liability. The waiver and
release are part of the consideration for issuance of the Notes. Such waiver may
not be effective to waive liabilities under the federal securities laws and it
is the view of the Commission that such a waiver is against public policy.

     7. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

     8. COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

     9. EFFECT OF HEADINGS. The Section headings herein are for convenience only
and shall not affect the construction hereof.

     10. THE TRUSTEE. The Trustee shall not be responsible in any manner
whatsoever for or in respect of the validity or sufficiency of this Supplemental
Indenture or for or


<PAGE>
                                                                               7

in respect of the recitals contained herein, all of which recitals are made
solely by the Guaranteeing Subsidiaries and the Company.



<PAGE>
                                                                               8



     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the date first above
written.

Dated:   November 9, 2001

                              L-3 COMMUNICATIONS CORPORATION


                              By: ______________________________________
                                     Name:
                                     Title:

                              COLEMAN RESEARCH CORPORATION
                              EER SYSTEMS, INC.
                              ELECTRODYNAMICS, INC.
                              HENSCHEL INC.
                              HYGIENETICS ENVIRONMENTAL SERVICES, INC.
                              INTERSTATE ELECTRONICS CORPORATION
                              KDI PRECISION PRODUCTS, INC.
                              L-3 COMMUNICATIONS AYDIN CORPORATION
                              L-3 COMMUNICATIONS DBS MICROWAVE, INC.
                              L-3 COMMUNICATIONS ESSCO, INC.
                              L-3 COMMUNICATIONS ILEX SYSTEMS, INC.
                              L-3 COMMUNICATIONS SPD TECHNOLOGIES, INC.
                              L-3 COMMUNICATIONS STORM CONTROL SYSTEMS, INC.
                              MICRODYNE CORPORATION
                              MPRI, INC.
                              PAC ORD INC.
                              POWER PARAGON, INC.
                              SOUTHERN CALIFORNIA MICROWAVE, INC.
                              SPD ELECTRICAL SYSTEMS, INC.
                              SPD HOLDINGS, INC.
                              SPD SWITCHGEAR INC.
                                       As Guaranteeing Subsidiaries

                              By: ______________________________________
                                     Name:
                                     Title:

<PAGE>
                                                                               9


Dated:  November 9, 2001      THE BANK OF NEW YORK
                              as Trustee


                              By: ______________________________________
                                     Name:
                                     Title:






<PAGE>




                      NOTATION ON SENIOR SUBORDINATED NOTE
                        RELATING TO SUBSIDIARY GUARANTEE


     Each Guaranteeing Subsidiary (as defined in the Supplemental Indenture (the
"Supplemental Indenture") dated November 9, 2001 among L-3 Communications
Corporation, a Delaware corporation, Coleman Research Corporation, a Florida
corporation, EER Systems, Inc., a Virginia corporation, Electrodynamics, Inc.,
an Arizona corporation, Henschel Inc., a Delaware corporation, Hygienetics
Environmental Services, Inc., a Delaware corporation, Interstate Electronics
Corporation, a California corporation, KDI Precision Products, Inc., a Delaware
corporation, L-3 Communications Aydin Corporation, a Delaware corporation, L-3
Communications DBS Microwave, Inc., a California corporation, L-3 Communications
ESSCO, Inc., a Delaware corporation, L-3 Communications ILEX Systems, Inc., a
Delaware corporation, L-3 Communications SPD Technologies, Inc., a Delaware
corporation, L-3 Communications Storm Control Systems, Inc., a California
corporation, Microdyne Corporation, a Maryland corporation, MPRI, Inc., a
Delaware corporation, Pac Ord Inc., a Delaware corporation, Power Paragon, Inc.,
a Delaware corporation, Southern California Microwave, Inc., a California
corporation, SPD Electrical Systems, Inc., a Delaware corporation, SPD Holdings,
Inc., a Delaware corporation and SPD Switchgear Inc., a Delaware corporation,
and The Bank of New York) (i) has jointly and severally unconditionally
guaranteed (a) the due and punctual payment of the principal of, premium and
interest on the Notes, whether at maturity or an interest payment date, by
acceleration, call for redemption or otherwise, (b) the due and punctual payment
of interest on the overdue principal and premium of, and interest on the Notes,
and (c) in case of any extension of time of payment or renewal of any Notes or
any of such other obligations, the same will be promptly paid in full when due
in accordance with the terms of the extension or renewal, whether at stated
maturity, by acceleration or otherwise and (ii) has agreed to pay any and all
costs and expenses (including reasonable attorneys" fees) incurred by the
Trustee or any Holder in enforcing any rights under this Subsidiary Guarantee.

     Notwithstanding the foregoing, in the event that the Subsidiary Guarantee
of any Guaranteeing Subsidiary would constitute or result in a violation of any
applicable fraudulent conveyance or similar law of any relevant jurisdiction,
the liability of such Guaranteeing Subsidiary under its Subsidiary Guarantee
shall be reduced to the maximum amount permissible under such fraudulent
conveyance or similar law.

     No past, present or future director, officer, employee, agent,
incorporator, stockholder or agent of any Guaranteeing Subsidiary, as such,
shall have any liability for any obligations of the Company or any Guaranteeing
Subsidiary under the Notes, any Subsidiary Guarantee, Indenture, any
supplemental indenture delivered pursuant to the Indenture by such Guaranteeing
Subsidiary or any Subsidiary Guarantees, or for any claim based on, in respect
of or by reason of such obligations or their creation. Each Holder by accepting
a Note waives and releases all such liability.

     This Subsidiary Guarantee shall be binding upon each Guaranteeing
Subsidiary and its successors and assigns and shall inure to the benefit of the
successors and assigns of the Trustee and the Holders and, in the event of any
transfer or assignment of rights by any Holder or the Trustee, the rights and
privileges herein conferred upon that party shall automatically


<PAGE>
                                                                               2

extend to and be vested in such transferee or assignee, all subject to the terms
and conditions hereof.



<PAGE>
                                                                               3



     This Subsidiary Guarantee shall not be valid or obligatory for any purpose
until the certificate of authentication on the Note upon which this Subsidiary
Guarantee is noted have been executed by the Trustee under the Indenture by the
manual signature of one of its authorized officers. Capitalized terms used
herein have the meaning assigned to them in the Indenture.

                                 COLEMAN RESEARCH CORPORATION
                                 EER SYSTEMS, INC.
                                 ELECTRODYNAMICS, INC.
                                 HENSCHEL INC.
                                 HYGIENETICS ENVIRONMENTAL SERVICES, INC.
                                 INTERSTATE ELECTRONICS CORPORATION
                                 KDI PRECISION PRODUCTS, INC.
                                 L-3 COMMUNICATIONS AYDIN CORPORATION
                                 L-3 COMMUNICATIONS DBS MICROWAVE, INC.
                                 L-3 COMMUNICATIONS ESSCO, INC.
                                 L-3 COMMUNICATIONS ILEX SYSTEMS, INC.
                                 L-3 COMMUNICATIONS SPD TECHNOLOGIES, INC.
                                 L-3 COMMUNICATIONS STORM CONTROL SYSTEMS, INC.
                                 MICRODYNE CORPORATION
                                 MPRI, INC.
                                 PAC ORD INC.
                                 POWER PARAGON, INC.
                                 SOUTHERN CALIFORNIA MICROWAVE, INC.
                                 SPD ELECTRICAL SYSTEMS, INC.
                                 SPD HOLDINGS, INC.
                                 SPD SWITCHGEAR INC.
                                          As Guaranteeing Subsidiaries



                                 By: ______________________________________
                                        Name:
                                        Title: