<PAGE>   1
                                                                  EXHIBIT 10.1.2

                      AMENDMENT NO. 2 TO CREDIT AGREEMENT

     This AMENDMENT No. 2 TO CREDIT AGREEMENT (this "Amendment"), is made and
entered into as of April 1, 1997, among COMMUNICATIONS & POWER INDUSTRIES, INC.
(the "Borrower"), COMMUNICATIONS & POWER INDUSTRIES HOLDING CORPORATION, CPI
SUBSIDIARY HOLDINGS, INC., COMMUNICATIONS & POWER INDUSTRIES INTERNATIONAL INC.,
COMMUNICATIONS & POWER INDUSTRIES ASIA INC., COMMUNICATIONS & POWER INDUSTRIES
ITALIA S.R.L., COMMUNICATIONS & POWER INDUSTRIES EUROPE LIMITED, COMMUNICATIONS
& POWER INDUSTRIES  CANADA INC., COMMUNICATIONS & POWER INDUSTRIES AUSTRALIA PTY
LIMITED, CPI SALES CORP., (collectively, the "Obligors"), BANKERS TRUST COMPANY,
as agent (the "Agent"), and the various lenders (the "Lenders") from time to
time party to the Credit Agreement, dated as of August 11, 1995 (as the same has
been amended and modified through the date hereof, the "Agreement"), among the
Obligors, the Agent and the Lenders.

     WHEREAS, the Obligors, the Agent and the Lenders desire to amend certain
provisions of the Agreement.

     NOW, THEREFORE, in consideration of the foregoing, the premises and mutual
covenants contained herein and for other valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto hereby agree as
follows:

     1.   Defined Terms. Unless otherwise defined herein, capitalized terms used
herein shall have the meanings given thereto in the Agreement.

     2.   Effectiveness of this Agreement. This Amendment shall become effective
and the Agreement shall be amended as provided herein on the first date on which
the Agent receives an executed copy of this Amendment from each Obligor and the
Required Lenders (the "Effective Date").

     3.   Amendments. As of the Effective Date:
     
     (a)  The reference to "$35,500,000" under the caption Consolidated EBITDA
set forth opposite Q2, 1997 in paragraph 1 of Annex F of the Agreement shall be
amended to read "$34,500,000".

     (b)  The reference to "1.10:1.00" under the caption "Ratio" set forth
opposite Q2, 1997 in paragraph 2 of Annex F of the Agreement shall be amended to
read "1.02:1.00".

     4.   Representations and Warranties. Each Obligor makes, as of the
Effective Date, each of the representations and warranties set forth in Section
3 of the Agreement, and such representations and warranties are, by this
reference, incorporated herein as if set forth herein in their entirety,
provided that references to "Loan Documents" shall, for purposes of this
paragraph, be deemed to include this Amendment.
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     5.   Miscellaneous.

     (a)  Except as expressly modified by this Agreement, the Agreement shall
continue to be and remain in full force and effect in accordance with its terms.
Any future reference to the Agreement shall from and after the Effective Date by
deemed to be a reference to the Agreement as amended by this Amendment.

     (b)  This Amendment may be executed in any number of counterparts, each of
which shall constitute an original, but all of which when taken together shall
constitute but one instrument.

     (c)  THIS AMENDMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH
THE LAWS OF THE STATE OF NEW YORK.

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


                                              COMMUNICATIONS & POWER
                                                INDUSTRIES, INC.


                                              By: /s/ LYNN E. HARVEY
                                                  ------------------------------
                                                  Name:  Lynn E. Harvey
                                                  Title: Chief Financial Officer
                                                         Treasurer and Secretary



                                              COMMUNICATIONS & POWER
                                              INDUSTRIES HOLDING CORPORATION


                                              By: /s/ LYNN E. HARVEY
                                                  ------------------------------
                                                  Name:  Lynn E. Harvey
                                                  Title: Chief Financial Officer
                                                         Treasurer and Secretary



                                              CPI SUBSIDIARY HOLDINGS, INC.


                                              By: /s/ LYNN E. HARVEY
                                                  ------------------------------
                                                  Name:  Lynn E. Harvey
                                                  Title: Secretary

                                       2

<PAGE>   3
                                        COMMUNICATIONS & POWER
                                        INDUSTRIES INTERNATIONAL INC.


                                        By /s/ Lynn E. Harvey
                                           ------------------------------
                                           Name:  Lynn E. Harvey
                                           Title: Secretary


                                        COMMUNICATIONS & POWER
                                        INDUSTRIES ASIA INC.         


                                        By /s/ Lynn E. Harvey
                                           ------------------------------
                                           Name:  Lynn E. Harvey
                                           Title: Treasurer


                                        COMMUNICATIONS & POWER
                                        INDUSTRIES ITALIA S.R.L.     


                                        By /s/ Lynn E. Harvey
                                           ------------------------------
                                           Name:  Lynn E. Harvey
                                           Title: (Per Power of Attorney)

                                        COMMUNICATIONS & POWER
                                        INDUSTRIES EUROPE LIMITED    


                                        By /s/ Lynn E. Harvey
                                           ------------------------------
                                           Name:  Lynn E. Harvey
                                           Title: Secretary


                                        COMMUNICATIONS & POWER
                                        INDUSTRIES CANADA INC.       


                                        By /s/ Lynn E. Harvey
                                           ------------------------------
                                           Name:  Lynn E. Harvey
                                           Title: Vice President



                                       3
<PAGE>   4
                                        COMMUNICATIONS & POWER
                                        INDUSTRIES AUSTRALIA
                                        PTY LIMITED



                                        By  /s/ LYNN E. HARVEY
                                           -----------------------------
                                           Name: Lynn E. Harvey     
                                           Title: (Per Power of Attorney)



                                        CPI SALES CORP.



                                        By  /s/ LYNN E. HARVEY
                                           -----------------------------
                                           Name: Lynn E. Harvey     
                                           Title: Secretary and Treasurer



                                        BANKERS TRUST COMPANY,
                                        as Lender and as Agent



                                        By -----------------------------
                                           Name:
                                           Title:



                                       4

<PAGE>   5
                                        COMMUNICATIONS & POWER
                                        INDUSTRIES AUSTRALIA
                                        PTY LIMITED



                                        By 
                                           -----------------------------
                                           Name: 
                                           Title: 



                                        CPI SALES CORP.



                                        By 
                                           -----------------------------
                                           Name: 
                                           Title: 



                                        BANKERS TRUST COMPANY,
                                        as Lender and as Agent



                                        By  /s/ ROBERT R. TELESCA     
                                           -----------------------------
                                           Name: Robert R. Telesca
                                           Title: Assistant Vice President



                                       4
<PAGE>   6
                                        DRESDNER BANK AG,
                                        New York Branch and 
                                        Grand Cayman Branch



                                        By  /s/ JOHN W. SWEENEY
                                           -----------------------------
                                           Name: John W. Sweeney    
                                           Title: Assistant Vice President


                                        By  /s/ CHRISTOPHER E. SARISKY
                                           -----------------------------
                                           Name: Christopher E. Sarisky
                                           Title: Assistant Treasurer



                                       5
<PAGE>   7
                                   FIRST BANK NATIONAL ASSOCIATION


                                   By /s/ ROBERT W. MILLER
                                     --------------------------
                                     Name: Robert W. Miller
                                     Title: Vice President





                                       6
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                                   MERRILL LYNCH SENIOR FLOATING
                                   RATE FUND, INC.

                                   
                                   By
                                     ---------------------------
                                     Name:
                                     Title:





                                       7
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                                   SENIOR DEBT PORTFOLIO
                                  
                                   By BOSTON MANAGEMENT AND RESEARCH,
                                      as Investment Adviser

                                   
                                   By /s/ [SIG]
                                     ---------------------------
                                     Name:
                                     Title:





                                       8
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                                   THE NIPPON CREDIT BANK, LTD.
                                   Los Angeles Agency

                                   
                                   By /s/ BERNARDO E. CORREA-HENSCHKE
                                     --------------------------------
                                     Name: Bernardo E. Correa-Henschke
                                     Title: Vice President & Senior Manager





                                       9
<PAGE>   11
                                   UNION BANK OF CALIFORNIA, N.A.

                                   
                                   By /s/ STEPHEN R. SWEENEY
                                     ---------------------------
                                     Name: Stephen R. Sweeney
                                     Title: Vice President





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