EXHIBIT 10.22

                             ASSUMPTION AGREEMENT



     ASSUMPTION AGREEMENT, dated as of May 21, 1998 (this "Agreement"), among
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DYNATECH CORPORATION, a Massachusetts corporation ("Holding"), TTC MERGER CO.
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LLC, a Delaware limited liability company wholly owned by Holding ("Newco"), and
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TELECOMMUNICATIONS TECHNIQUES CO., LLC, a Delaware limited liability company
wholly owned by Holding ("TTC"), and consented to by Morgan Guaranty Trust
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Company of New York, as administrative agent (in such capacity, the
"Administrative Agent") for the banks and other financial institutions (the
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"Lenders") from time to time parties to the Credit Agreement (as hereinafter
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defined).


                              W I T N E S S E T H:
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     WHEREAS, Holding, Newco and the Administrative Agent are parties to the
Credit Agreement, dated as of May 21, 1998 (as amended, supplemented, waived or
otherwise modified from time to time, the "Credit Agreement"), among Holding,
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Newco, the Lenders, the Administrative Agent, Credit Suisse First Boston, as
syndication agent (in such capacity, the "Syndication Agent"), and The Chase
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Manhattan Bank, as documentation agent (in such capacity, the "Documentation
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Agent"); and
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     WHEREAS, each of Holding and Newco wishes to assign, transfer and convey to
TTC all of Holding's and Newco's rights, respectively, as "Borrower" under, and
TTC wishes to assume from Holding and Newco all of Holding's and Newco's
obligations and liabilities as "Borrower" under, the Credit Agreement and any
Notes, any Letters of Credit and the other Credit Documents (as each of such
terms is defined in the Credit Agreement); and

     WHEREAS, pursuant to subsection 12.11 of the Credit Agreement, Holding and
Newco have agreed to execute and deliver, and to cause, TTC to execute and
deliver, this Agreement; and

     WHEREAS, pursuant to subsection 12.11 of the Credit Agreement, the
Administrative Agent is authorized to consent to this Agreement on behalf of the
Lenders;

     NOW, THEREFORE, the parties hereto hereby agree as follows:

     I.  Defined Terms.  Terms defined in the Credit Agreement and used herein
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shall have the meanings given to them in the Credit Agreement.

 
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     II.  Assignment and Assumption.
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     1.   Assignment of Rights and Obligations.  Effective as of 12:01 A.M. (New
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York City time) on May 21, 1998, each of Holding and Newco hereby irrevocably
assigns, transfers and conveys to TTC all of Holding's and Newco's rights,
obligations, covenants, agreements, duties and liabilities as "Borrower" under
or with respect to the Credit Agreement, any Notes, any Letters of Credit, any
of the other Credit Documents (other than this Agreement and the Collateral
Agreement) and any and all certificates and other documents executed by Holding
and Newco in connection therewith; provided, however, that each of Holding and
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Newco understands and agrees that such assignment, transfer and conveyance shall
not be effective with respect to, or in any way release Holding or Newco from
any of its obligations, covenants, agreements, duties and liabilities under or
with respect to this Agreement and the Collateral Agreement.

     2.   Assumption of Agreements and Obligations.  Effective as of 12:01 A.M.
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(New York City time) on May 21, 1998 (the "Effective Date"), TTC hereby
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expressly assumes, confirms and agrees to perform and observe all of the
indebtedness, obligations (including, without limitation, all obligations in
respect of the Loans and the Letters of Credit), covenants, agreements, terms,
conditions, duties and liabilities of Holding and Newco as "Borrower" under and
with respect to the Credit Agreement, any Notes, any Letters of Credit, any of
the other Credit Documents (other than this Agreement and the Collateral
Agreement) and any and all certificates and other documents executed by Holding
and Newco in connection therewith as fully as if TTC were originally the obligor
in respect thereof and the signatory thereto; provided, however, that each of
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Holding and Newco understands and agrees that such assumption shall not be
effective with respect to, or in any way obligate TTC to perform and observe any
obligations, covenants, agreements, terms, conditions, duties or liabilities of
Holding or Newco under or with respect to this Agreement and the Collateral
Agreement.  At all times after the effectiveness of such assumption, with
respect to all Loans made to or for the account of Holding or Newco prior to the
effectiveness of such assumption, TTC shall have the obligations of, and Holding
and Newco shall no longer be or have the obligations of, the "Borrower" within
the meaning of and for all purposes of the Credit Agreement.  In addition, at
all times after the effectiveness of such assumption, all references to the
"Borrower" in the Credit Agreement, any Notes, any Letter of Credit, any of the
other Credit Documents and any and all certificates and other documents executed
by Holding and Newco in connection therewith shall be deemed to be references to
TTC.

     3.   Amendment to the Credit Agreement.  The Credit Agreement is hereby
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deemed to be amended to the extent, but only to the extent, necessary to effect
the assignment and assumption provided for hereby.

     4.   Replacement Notes.  TTC agrees to execute and deliver, on the 
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effective date of the assumption provided for by subsection II.2. hereof, to 
each of the Lenders then holding Notes, if any, new Notes payable to the order 
of such Lender (such new Notes, "Replacement Notes") in exchange for the Notes 
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of Holding or Newco then held by such Lender (the "Old Notes"). Each Replacement
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Note shall be identical in all respects to the corresponding Old Note or Old
Notes, as the case may be, except that the obligor on such Replacement Notes
shall be TTC instead of Holding and Newco.

 
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     III.  General.
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     1.    Representation and Warranties.  To induce the Administrative Agent,
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acting on behalf of the Lenders, to consent to the assignment and assumption
provided for in Section II. above, each of Holding, Newco and TTC hereby
represents and warrants to the Administrative Agent and each Lender as of the
date hereof and as of the date of such assignment and assumption that:

     (a)   Corporate Power; Authorization; Enforceable Obligations.  (i) Such
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party has the corporate power and authority, and the legal right, to make,
deliver and perform this Agreement and, in the case of TTC, each of the
Replacement Notes, and to perform each of the other Credit Documents to which it
is a party, as amended hereby, and has taken all necessary corporate action to
authorize the execution, delivery and performance of this Agreement and, in the
case of TTC, each of the Replacement Notes, and the performance of such other
Credit Documents, as so amended.

     (ii)  No consent or authorization of, approval by, notice to, filing with,
or other similar act by or in respect of, any Governmental Authority or any
other Person is required to be obtained or made by or on behalf of Holding,
Newco or TTC in connection with the execution and delivery of this Agreement or,
in the case of TTC, each of the Replacement Notes, or with the performance,
validity or enforceability of each of the other Credit Documents to which it is
a party, as amended hereby, except for (w) consents, authorizations, notices and
filings described in Schedule 10.4(a) to the Credit Agreement, all of which have
been obtained or made or have the status described therein, (x) filings to
perfect the Liens created by the Security Documents, (y) filings pursuant to the
Assignment of Claims Act of 1940, as amended (31 U.S.C. (S) 3727 et seq.), in
respect of Accounts of Holding and its Subsidiaries the obligor on which is the
United States of America or any department, agency or instrumentality thereof
and (z) consents, authorizations, notices and filings which the failure to
obtain or make would not reasonably be expected to have a Material Adverse
Effect.

     (iii) This Agreement and, in the case of TTC, each of the Replacement
Notes, has been or will have been duly executed and delivered on behalf of such
party.

     (iv)  This Agreement, each of the other Credit Documents to which it is a
party, as amended hereby, and, in the case of TTC, each of the Replacement
Notes, constitutes or will constitute, as the case may be, a legal, valid and
binding obligation of such party enforceable against such party in accordance
with its terms, except as enforceability may be limited by applicable
bankruptcy, insolvency, reorganization, moratorium or similar laws affecting the
enforcement of creditors' rights generally and by general equitable principles
(whether enforcement is sought by proceedings in equity or at law).

     (b)   No Legal Bar.  Except as previously disclosed in writing to the
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Lenders on or prior to the Effective Date, the execution, delivery and
performance of this Agreement and, in the case of TTC, each of the Replacement
Notes, and the performance of each of the other Credit Documents to which it is
a party, as amended hereby, (i) will not violate any Requirement of Law or
Contractual Obligation of such party or of any of its Subsidiaries in
any respect that 

 
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would reasonably be expected to have a Material Adverse Effect and (ii) will not
result in, or require, the creation or imposition of any Lien (other than Liens
created by the Security Documents or permitted under subsection 14.2 of the
Credit Agreement) on any of its or their respective properties or revenues
pursuant to any such Requirement of Law or Contractual Obligation.

     (c)  Representations and Warranties.  TTC hereby represents and warrants
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that the representations and warranties made by Holding, Newco and TTC (each in
its capacity as Holding, Newco or TTC, as the case may be, and in its capacity
as the "Borrower") in the Credit Documents are true and correct in all material
respects on and as of the date hereof, before and after giving effect to the
effectiveness of this Agreement, as if made on and as of the date hereof.

     2.  No Other Amendments; Confirmation.  Except as expressly amended,
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modified and supplemented hereby, the provisions of the Credit Agreement and the
other Credit Documents are and shall remain in full force and effect.

     3.  Affirmation of Credit Documents.  Each of the Credit Parties hereby
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consents to the execution and delivery of this Agreement and any Replacement
Notes and confirms, reaffirms and restates its obligations under each of the
Credit Documents to which it is a party pursuant to the terms thereof.

     4.  GOVERNING LAW; COUNTERPARTS.  (a) THIS AGREEMENT AND THE RIGHTS AND
         ---------------------------                                        
OBLIGATIONS OF THE PARTIES UNDER THIS AGREEMENT SHALL BE GOVERNED BY, AND
CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK,
WITHOUT GIVING EFFECT TO ITS PRINCIPLES OR RULES OF CONFLICTS OF LAWS TO THE
EXTENT SUCH PRINCIPLES OR RULES WOULD REQUIRE THE APPLICATION OF THE LAWS OF
ANOTHER JURISDICTION.

     (b)  This Agreement may be executed by one or more of the parties to this
Agreement on any number of separate counterparts, and all of said counterparts
taken together shall be deemed to constitute one and the same instrument.  A set
of the copies of this Agreement signed by all the parties shall be lodged with
each of Holding, Newco, TTC and the Administrative Agent.  This Agreement may be
delivered by facsimile transmission of the relevant signature pages hereof.

     5.  Integration.  This Agreement and the other Credit Documents represent
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the entire agreement of the parties hereto with respect to the subject matter
hereof and there are no promises or representations by the parties hereto
relative to the subject matter hereof not reflected or referred to herein or
therein.

     6.  Section Headings.  The section headings used in this Agreement are for
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convenience of reference only and are not to affect the construction hereof or
be taken into consideration in the interpretation hereof.

     7.  Submission To Jurisdiction; Waivers.  Each of the parties hereto hereby
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irrevocably and unconditionally:

 
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          (a)  submits for itself and its property in any legal action or
     proceeding relating to this Agreement and the other Credit Documents to
     which it is a party, or for recognition and enforcement of any judgment in
     respect thereof, to the non-exclusive general jurisdiction of the courts of
     the State of New York, the courts of the United States of America for the
     Southern District of New York, and appellate courts from any thereof;

          (b)  consents that any such action or proceeding may be brought in
     such courts and waives any objection that it may now or hereafter have to
     the venue of any such action or proceeding in any such court or that such
     action or proceeding was brought in an inconvenient court and agrees not to
     plead or claim the same;

          (c)  agrees that service of process in any such action or proceeding
     may be effected by mailing a copy thereof by registered or certified mail
     (or any substantially similar form of mail), postage prepaid, to such party
     at its address referred to in the other Credit Documents to which it is a
     party or at such other address of which the other parties shall have been
     notified pursuant thereto;

          (d)  agrees that nothing herein shall affect the right to effect
     service of process in any other manner permitted by law or shall limit the
     right to sue in any other jurisdiction; and

          (e)  waives, to the maximum extent not prohibited by law, any right it
     may have to claim or recover in any legal action or proceeding referred to
     in this subsection any punitive damages.

     8.  Successors and Assigns.  This Agreement shall be binding upon and inure
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to the benefit of Holding, Newco and TTC and their respective successors and
assigns, and the Administrative Agent and the Lenders and their respective
successors, indorsees, transferees and assigns.

     9.  WAIVER OF JURY TRIAL.  THE PARTIES HERETO HEREBY IRREVOCABLY AND
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UNCONDITIONALLY WAIVE TRIAL BY JURY IN ANY LEGAL ACTION OR PROCEEDING RELATING
TO THIS AGREEMENT OR ANY OTHER CREDIT DOCUMENT AND FOR ANY COUNTERCLAIM THEREIN.

 
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     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed and delivered by their respective proper and duly authorized
officers as of the day and year first above written.

                                      DYNATECH CORPORATION


                                      By:________________________________
                                        Name:
                                        Title:


                                      TTC MERGER CO. LLC

                                       By:  Dynatech Corporation, its sole 
                                            member
                                                        


                                      By:________________________________
                                        Name:
                                        Title:


                                      TELECOMMUNICATIONS TECHNIQUES CO., LLC

                                        By: Dynatech Corporation, its sole 
                                            member

                                      By:________________________________
                                        Name:
                                        Title:

 
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Consented and Agreed
(for purposes of subsection III.3. only):

AIRSHOW, INC.


By: _______________________________
  Name:
  Title:


COMCOTEC, INC.


By: _______________________________
  Name:
  Title:


DATAVIEWS CORPORATION


By: ________________________________
  Name:
  Title:


DA VINCI SYSTEMS, INC.


By: ________________________________
  Name:
  Title:


INDUSTRIAL COMPUTER SOURCE


By: _______________________________
  Name:
  Title:

 
                                                                               8

ITRONIX CORPORATION


By: _______________________________
  Name:
  Title:


PARALLAX GRAPHICS, INC.


By: _______________________________
  Name:
  Title:


SYNERGISTIC SOLUTIONS, INC.


By: _______________________________
  Name:
  Title:


TELE-PATH INSTRUMENTS, INC.


By: _______________________________
  Name:
  Title:


Consented to:


MORGAN GUARANTY TRUST COMPANY OF       
   NEW YORK, as Administrative Agent


By: _______________________________
  Name:
  Title: