EXHIBIT 10.73

                     SUPPLEMENTAL INDENTURE TO BE DELIVERED
                          BY GUARANTEEING SUBSIDIARIES

     Supplemental Indenture (this "Supplemental Indenture"), dated as of August
1, 2006, among L-3 Communications Holdings, Inc. (or its permitted successor), a
Delaware corporation (the "Company"), each a direct or indirect subsidiary of
the Company signatory hereto (each, a "Guaranteeing Subsidiary", and
collectively, the "Guaranteeing Subsidiaries"), and The Bank of New York, as
trustee under the indenture referred to below (the "Trustee").

                                   WITNESSETH
                                   ----------

          WHEREAS, the Company has heretofore executed and delivered to the
Trustee an indenture (the "Indenture"), dated as of July 29, 2005 providing for
the issuance of up to $700,000,000 of 3.0% Convertible Contingent Debt
Securities (CODES) due 2035 (the "CODES");

          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 (as defined in the
Indenture) under the CODES and the Indenture on the terms and conditions set
forth herein (the "Subsidiary Guarantee"); and

          WHEREAS, pursuant to the Indenture, the parties hereto are authorized
to execute and deliver this Supplemental Indenture and the Trustee has
determined that this Supplemental Indenture is in form satisfactory to it.

          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 CODES 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:

               (a)  Such Guaranteeing Subsidiary, jointly and severally with all
                    other current and future guarantors of the CODES
                    (collectively, the "Guarantors" and each, a "Guarantor"),
                    unconditionally guarantees to each Holder of a CODE
                    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 CODES or
                    the Obligations of the Company under the Indenture or the
                    CODES, that:

                    (i)  the principal of and interest (including Contingent
                         Interest and Additional Interest, if any) on the CODES
                         will be promptly paid in full when due, whether at
                         maturity, by acceleration, redemption or otherwise, and
                         interest on the overdue principal of and interest
                         (including Contingent Interest and Additional Interest,
                         if any) on the CODES, to the extent lawful, and all
                         other Obligations of the Company to the Holders or the
                         Trustee


                                        1



                         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 CODES 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 A to the Indenture
                    shall be endorsed by an Officer of such Guaranteeing
                    Subsidiary on each CODE 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 CODE 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 CODE
                    on which a Subsidiary Guarantee is endorsed, the Subsidiary
                    Guarantee shall be valid nevertheless.

               (d)  The delivery of any CODE 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, to the extent permitted by
                    applicable law, be unconditional, regardless of the
                    validity, regularity or enforceability of the CODES or the
                    Indenture, the absence of any action to enforce the same,
                    any waiver or consent by any Holder of the CODES 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, to the extent permitted by
                    applicable law, hereby waives diligence, presentment, demand
                    of payment, filing of


                                        2



                    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 CODES 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 4 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;

                    (ii)  in the event of any declaration of acceleration of
                          such Obligations as provided in Article 4 of the
                          Indenture, such Obligations (whether or not due and
                          payable) shall forthwith become due and payable by
                          such Guaranteeing Subsidiary for the purpose of the
                          Subsidiary Guarantee made pursuant to this
                          Supplemental Indenture; and

                    (iii) 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 6 and 9 of the Indenture,
                    nothing contained in the Indenture, this Supplemental
                    Indenture or in the CODES shall prevent (i) any
                    consolidation or merger of any Guaranteeing Subsidiary with
                    or into the Company or any other Guarantor, (ii) 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 or (iii)
                    any merger of a Guarantor with or into with an


                                        3



                    Affiliate of that Guarantor that has not significant assets
                    or liabilities and was incorporated solely for the purpose
                    of reincorporating such Guarantor in another State of the
                    United States so long as the amount of Indebtedness of the
                    Company and the domestic non-Guarantor subsidiaries is not
                    increased thereby.

               (b)  Except as set forth in Article 9 of the Indenture, nothing
                    contained in the Indenture, this Supplemental Indenture or
                    in the CODES shall prevent any consolidation or merger of
                    any Guaranteeing Subsidiary with or into any Person
                    organized under the laws of the United States of America,
                    any state thereof, the District of Columbia or any territory
                    thereof 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 any Person organized under the laws of the United States
                    of America, any state thereof, the District of Columbia or
                    any territory thereof 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 such Guaranteeing Subsidiary is not the
                    surviving corporation in the merger), by supplemental
                    indenture satisfactory in form to the Trustee, executed and
                    delivered to the Trustee, by any Person formed by such
                    consolidation, or into which such Guaranteeing Subsidiary
                    shall have been merged, or by any Person which shall have
                    acquired such property, (ii) immediately after giving effect
                    to such consolidation, merger, sale or conveyance no Default
                    or Event of Default exists and (iii) such transaction will
                    only be permitted under the Indenture if it would be
                    permitted under the terms of all of the indentures governing
                    the Outstanding Senior Subordinated Notes as the same are in
                    effect on the date of the Indenture (whether or not those
                    indentures are subsequently amended, waived, modified or
                    terminated or expire and whether or not any of these notes
                    continue to be outstanding).

               (c)  In case of any such consolidation, merger, sale or
                    conveyance and upon the assumption by the successor
                    corporation, by supplemental indenture, 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 such
                    Guaranteeing Subsidiary, such successor Person shall succeed
                    to and be substituted for such Guaranteeing Subsidiary with
                    the same effect as if it had been named herein as the
                    Guaranteeing Subsidiary. Such successor Person thereupon may
                    cause to be signed any or all of the Subsidiary Guarantees
                    to be endorsed upon the CODES


                                        4



                    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. If the assets
                    sold in such sale or other disposition (including by way of
                    merger or consolidation) 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. 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, the Trustee shall execute any documents
                    reasonably required in order to evidence the release of the
                    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 (including Contingent Interest and
                    Additional Interest, if any) on the CODES 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
                    Excluded Subsidiary in accordance with the terms of the
                    Indenture and the indentures governing the Outstanding
                    Senior Subordinated Notes as the same are in effect on the
                    date of the Indenture (whether or not those indentures are
                    subsequently amended, waived, modified or terminated or
                    expire and whether or not any of those notes continue to be
                    outstanding), such Guaranteeing Subsidiary shall be released
                    and relieved of all 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 and the indentures governing , the Outstanding
                    Senior Subordinated Notes as


                                        5



                    the same are in effect on the date of the Indenture (whether
                    or not those indentures are subsequently amended, waived,
                    modified or terminated or expire and whether or not any of
                    those notes continue to be outstanding), 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 CODES and
                    for the other obligations of any Guaranteeing Subsidiary
                    under the Indenture as provided herein.

               (c)  Upon any Guarantor being released from its guarantees of,
                    and all pledges and security interests granted in connection
                    with, Indebtedness of the Company or any of its Subsidiaries
                    (other than a Foreign Subsidiary), such Guarantor shall be
                    released and relieved of its obligations under this
                    Supplemental Indenture.

          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 CODES, 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
CODES by accepting a CODE waives and releases all such liability. The waiver and
release are part of the consideration for issuance of the CODES. Such waiver may
not be effective to waive liabilities under the federal securities laws and it
is the view of the SEC that such a waiver is against public policy.

          7. SUBORDINATION OF SUBSIDIARY GUARANTEES; ANTI-LAYERING. No
Guaranteeing Subsidiary shall incur, create, issue, assume, guarantee or
otherwise become liable for any Indebtedness that is subordinate or junior in
right of payment to any Senior Debt of a Guaranteeing Subsidiary and senior in
any respect in right of payment to any of the Subsidiary Guarantees. No
Indebtedness shall be deemed to be subordinated or junior in right of payment to
any other Indebtedness solely by virtue of being unsecured.

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

          9. 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.

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

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


                                        6



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

Dated: August 1, 2006                   L-3 COMMUNICATIONS HOLDINGS, INC.


                                        By: /s/ Christopher C. Cambria
                                            ------------------------------------
                                            Name: Christopher C. Cambria
                                            Title: Senior Vice President,
                                                   Secretary and General Counsel



Dated: August 1, 2006

Apcom, Inc., a Maryland corporation
Broadcast Sports Inc., a Delaware corporation
Crestview Aerospace Corporation, a Delaware corporation
D.P. Associates, 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
LinCom Wireless, Inc., a Delaware corporation
L-3 Communications Advanced Laser Systems Technology, Inc., a Florida
   corporation
L-3 Communications Aeromet, Inc., an Oregon corporation
L-3 Communications AIS GP Corporation, a Delaware corporation
L-3 Communications Applied Signal and Image Technology, Inc., a Maryland
   corporation
L-3 Communications Avionics Systems, Inc., a Delaware corporation
L-3 Communications Avisys Corporation, a Texas corporation
L-3 Communications Aydin Corporation, a Delaware corporation
L-3 Communications CE Holdings, Inc., a Delaware corporation
L-3 Communications Cincinnati Electronics, Inc., an Ohio corporation
L-3 Communications CSI, Inc., a California corporation
L-3 Communications CyTerra Corporation, a Delaware corporation
L-3 Communications Dynamic Positioning and Control Systems, Inc., a California
   corporation
L-3 Communications Electron Technologies, Inc., a Delaware corporation
L-3 Communications EO/IR, Inc., a Florida corporation
L-3 Communications EOTech, Inc., a Delaware corporation
L-3 Communications ESSCO, Inc., a Delaware corporation
L-3 Communications Government Services, Inc., a Virginia corporation
L-3 Communications ILEX Systems, Inc., a Delaware corporation
L-3 Communications InfraredVision Technology Corporation, a California
   corporation
L-3 Communications Investments, Inc., a Delaware corporation
L-3 Communications Klein Associates, Inc., a Delaware corporation
L-3 Communications MAS (US) Corporation, a Delaware corporation
L-3 Communications MariPro, Inc., a California corporation
L-3 Communications Mobile-Vision, Inc., a New Jersey corporation
L-3 Communications Nautronix Holdings, Inc., a Delaware corporation
L-3 Communications SafeView, Inc., a Delaware corporation
L-3 Communications Security and Detection Systems, Inc., a Delaware corporation
L-3 Communications Sonoma EO, Inc., a California corporation
L-3 Communications SSG-Tinsley, Inc., a Delaware corporation
L-3 Communications TCS, Inc., a Delaware corporation
L-3 Communications Titan Corporation, a Delaware corporation
L-3 Communications Westwood Corporation, a Nevada corporation
MCTI Acquisition Corporation, a Maryland Corporation
Microdyne Communications Technologies Incorporated, a Maryland corporation
Microdyne Corporation, a Maryland corporation
Microdyne Outsourcing Incorporated, a Maryland corporation
MPRI, Inc., a Delaware corporation
Pac Ord Inc., a Delaware corporation
Power Paragon, Inc., a Delaware corporation
SPD Electrical Systems, Inc., a Delaware corporation



SPD Switchgear Inc., a Delaware corporation
SYColeman Corporation, a Florida corporation
Tinsley Laboratories, Inc., a California corporation
Titan Facilities, Inc., a Virginia corporation
Troll Technology Corporation, a California corporation
Wescam Air Ops Inc., a Delaware corporation
Wescam Holdings (US) Inc., a Delaware corporation
Wolf Coach, Inc., a Massachusetts corporation

L-3 Communications Flight Capital LLC, a Delaware limited liability company
L-3 Communications Flight International Aviation LLC, a Delaware limited
   liability company
L-3 Communications Integrated Systems L.P., a Delaware limited partnership
L-3 Communications Vector International Aviation LLC, a Delaware limited
   liability company
L-3 Communications Vertex Aerospace LLC, a Delaware limited liability company
Wescam Air Ops LLC, a Delaware limited liability company
Wescam LLC, a Delaware limited liability company

                                        As Guaranteeing Subsidiaries


                                        By: /s/ Christopher C. Cambria
                                            ------------------------------------
                                            Name: Christopher C. Cambria
                                            Title: Vice President and Secretary



Dated: August 1, 2006                   THE BANK OF NEW YORK,
                                        as Trustee


                                        By: /s/ Franca Ferrera
                                            ------------------------------------
                                            Name: Franca Ferrera
                                            Title: Assistant Vice President



      NOTATION ON SENIOR SUBORDINATED NOTE RELATING TO SUBSIDIARY GUARANTEE

          Pursuant to the Supplemental Indenture (the "Supplemental Indenture")
dated as of August 1, 2006 among L-3 Communications Holdings, Inc., the
Guarantors party thereto (each a "Guarantor" and collectively the "Guarantors")
and The Bank of New York, as trustee (the "Trustee"), each Guarantor (i) has
jointly and severally unconditionally guaranteed (a) the due and punctual
payment of the principal of and interest (including Contingent Interest and
Additional Interest, if any) on the CODES, 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 interest (including
Contingent Interest and Additional Interest, if any) on the CODES, and (c) in
case of any extension of time of payment or renewal of any CODES 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 the Subsidiary Guarantee (as defined in the
Supplemental Indenture). This Guarantee is subordinated to the Senior Debt of
each Guarantor to extent set forth in Article 13 of the Indenture.

          Notwithstanding the foregoing, in the event that the Subsidiary
Guarantee of any Guarantor would constitute or result in a violation of any
applicable fraudulent conveyance or similar law of any relevant jurisdiction,
the liability of such Guarantor 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 Guarantor, as such, shall have any
liability for any Obligations of the Company or any Guarantor under the CODES,
any Subsidiary Guarantee, the Indenture, any supplemental indenture delivered
pursuant to the Indenture by such Guarantor, or for any claim based on, in
respect of or by reason of such Obligations or their creation. Each Holder by
accepting a CODE waives and releases all such liability.

          The Subsidiary Guarantee shall be binding upon each Guarantor 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 extend to and be vested in
such transferee or assignee, all subject to the terms and conditions hereof.

          The Subsidiary Guarantee shall not be valid or obligatory for any
purpose until the certificate of authentication on the CODE upon which the
Subsidiary Guarantee is noted has 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, dated as
of July 29, 2005, among L-3 Communications Holdings, Inc., the Guarantors party
thereto and the Trustee.



Dated: August 1, 2006

Apcom, Inc., a Maryland corporation
Broadcast Sports Inc., a Delaware corporation
Crestview Aerospace Corporation, a Delaware corporation
D.P. Associates, 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
LinCom Wireless, Inc., a Delaware corporation
L-3 Communications Advanced Laser Systems Technology, Inc., a Florida
   corporation
L-3 Communications Aeromet, Inc., an Oregon corporation
L-3 Communications AIS GP Corporation, a Delaware corporation
L-3 Communications Applied Signal and Image Technology, Inc., a Maryland
   corporation
L-3 Communications Avionics Systems, Inc., a Delaware corporation
L-3 Communications Avisys Corporation, a Texas corporation
L-3 Communications Aydin Corporation, a Delaware corporation
L-3 Communications CE Holdings, Inc., a Delaware corporation
L-3 Communications Cincinnati Electronics, Inc., an Ohio corporation
L-3 Communications CSI, Inc., a California corporation
L-3 Communications CyTerra Corporation, a Delaware corporation
L-3 Communications Dynamic Positioning and Control Systems, Inc., a California
   corporation
L-3 Communications Electron Technologies, Inc., a Delaware corporation
L-3 Communications EO/IR, Inc., a Florida corporation
L-3 Communications EOTech, Inc., a Delaware corporation
L-3 Communications ESSCO, Inc., a Delaware corporation
L-3 Communications Government Services, Inc., a Virginia corporation
L-3 Communications ILEX Systems, Inc., a Delaware corporation
L-3 Communications InfraredVision Technology Corporation, a California
   corporation
L-3 Communications Investments, Inc., a Delaware corporation
L-3 Communications Klein Associates, Inc., a Delaware corporation
L-3 Communications MAS (US) Corporation, a Delaware corporation
L-3 Communications MariPro, Inc., a California corporation
L-3 Communications Mobile-Vision, Inc., a New Jersey corporation
L-3 Communications Nautronix Holdings, Inc., a Delaware corporation
L-3 Communications SafeView, Inc., a Delaware corporation
L-3 Communications Security and Detection Systems, Inc., a Delaware corporation
L-3 Communications Sonoma EO, Inc., a California corporation
L-3 Communications SSG-Tinsley, Inc., a Delaware corporation
L-3 Communications TCS, Inc., a Delaware corporation
L-3 Communications Titan Corporation, a Delaware corporation
L-3 Communications Westwood Corporation, a Nevada corporation
MCTI Acquisition Corporation, a Maryland Corporation
Microdyne Communications Technologies Incorporated, a Maryland corporation
Microdyne Corporation, a Maryland corporation
Microdyne Outsourcing Incorporated, a Maryland corporation
MPRI, Inc., a Delaware corporation
Pac Ord Inc., a Delaware corporation
Power Paragon, Inc., a Delaware corporation



SPD Electrical Systems, Inc., a Delaware corporation
SPD Switchgear Inc., a Delaware corporation
SYColeman Corporation, a Florida corporation
Tinsley Laboratories, Inc., a California corporation
Titan Facilities, Inc., a Virginia corporation
Troll Technology Corporation, a California corporation
Wescam Air Ops Inc., a Delaware corporation
Wescam Holdings (US) Inc., a Delaware corporation
Wolf Coach, Inc., a Massachusetts corporation

L-3 Communications Flight Capital LLC, a Delaware limited liability company
L-3 Communications Flight International Aviation LLC, a Delaware limited
   liability company
L-3 Communications Integrated Systems L.P., a Delaware limited partnership
L-3 Communications Vector International Aviation LLC, a Delaware limited
   liability company
L-3 Communications Vertex Aerospace LLC, a Delaware limited liability company
Wescam Air Ops LLC, a Delaware limited liability company
Wescam LLC, a Delaware limited liability company

                                        As Guaranteeing Subsidiaries


                                        By: /s/ Christopher C. Cambria
                                            ------------------------------------
                                            Name: Christopher C. Cambria
                                            Title: Vice President and Secretary