<PAGE>   1

                                                                   EXHIBIT 10.16

                            UNSECURED PROMISSORY NOTE



$5,750,000                                               Los Angeles, California
                                                               December __, 2000


        FOR VALUE RECEIVED, Communications & Power Industries Holding
Corporation, a Delaware corporation (the "Borrower"), hereby absolutely and
unconditionally promises to pay to the order of Communications & Power
Industries, Inc., a Delaware corporation (the "Lender"), at such place as Lender
may designate to Borrower in writing, in lawful money of the United States, the
principal sum of Five Million Seven Hundred Fifty Thousand Dollars ($5,750,000)
(the "Principal Amount") on December __, 2009 (the "Maturity Date").

        In addition, Borrower hereby absolutely and unconditionally promises to
pay to the order of Lender interest on the Principal Amount, together with any
amounts otherwise owing under this Unsecured Promissory Note (this "Note"),
quarterly in arrears on December 31, March 31, June 30, and September 30 of each
year commencing December 31, 2000 and if different, on the Maturity Date (each,
an "Interest Payment Date") at the rate of 15.5% per annum, until the Principal
Amount is paid. Such interest shall accrue from the most recent date to which
interest has been paid or duly provided for or, if no such interest has been
paid or duly provided for, from December __, 2000 until the Maturity Date.
Interest shall be paid in cash, except that, on any Interest Payment Date,
Borrower will have the option to pay up to 35.25% of the interest payable on
such date by issuing additional notes which shall contain similar terms as
contained herein (the "Additional Notes"), in a principal amount equal to the
interest Borrower elected not to pay in cash.

        This Note and all Additional Notes, are each pre-payable, in whole or in
part, without premium or penalty, at any time, at the option of the Borrower;
provided, however, that all accrued interest on the principal amount so pre-paid
shall also be paid on the date of prepayment.

        Notwithstanding anything to the contrary herein, if any one or more of
the following events shall occur (each, an "Event of Default"): (a) failure to
pay any amount owing by the Borrower hereunder when due and payable within 15
business days following the date such payment is due, (b) with notice or passage
of time, or both, requisite holders of any of the Lender's 12% Senior
Subordinated Notes due 2005 (the "Senior Subordinated Notes") or, the Trustee
under the Indenture dated as of August 11, 1995, under which such Senior
Subordinated Notes were issued, shall have the right to cause such notes to
accelerate and become immediately payable, (c) the initiation of any voluntary
bankruptcy, insolvency, moratorium, receivership, assignment for the benefit of
creditors generally or reorganization proceeding by or against the Borrower, or
(d) the entry of a bankruptcy decree or initiation of any involuntary
bankruptcy, insolvency, moratorium, receivership, or reorganization proceeding
in respect to the Borrower and such proceeding or decree described in this
clause (d) shall continue for sixty (60) days without having been dismissed,
bonded or discharged;


<PAGE>   2

then, (1) upon the occurrence of any Event of Default described in clauses (c)
or (d), automatically, and (2) upon the occurrence of any other Event of
Default, at Lender's option, the entire unpaid principal balance of this Note
and all of the unpaid interest accrued thereon shall be immediately due and
payable, together with all costs, fees and expenses payable in respect hereof.

        No delay or omission on the part of the Lender or any holder hereof in
exercising any right hereunder shall operate as a waiver of such right or any
other right of the Lender or of such holder, nor shall any delay, omission or
waiver of any one occasion be deemed a bar to or waiver of the same or any other
right or any other occasion. The Borrower and every endorser and guarantor of
this Note regardless of the time, order or place of signing hereby waives
presentment, demand, protest and notice of every kind, and assents to any
extension or postponement of the time for payment or any other indulgence, to
any substitution, exchange or release of collateral, and to the addition or
release of any other party or person or entity primarily or secondarily liable.

        All costs incurred in any litigation arising from this Note shall be
borne by the prevailing party. All other expenses of enforcement of the Lender's
rights hereunder (including reasonable legal and other professional fees) shall
be for the account of the Borrower.

        THIS NOTE SHALL FOR ALL PURPOSES BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF CALIFORNIA (WITHOUT REFERENCE TO
CONFLICTS OF LAW).

        This Note shall be binding upon the Borrower's successors and assigns,
and shall inure to the benefit of the Lender's successors and assigns.

        IN WITNESS WHEREOF, the Borrower has caused this Note to be executed by
its duly authorized officer to take effect as of the date first herein above
written.

                                       COMMUNICATIONS & POWER INDUSTRIES
                                       HOLDING CORPORATION


                                       By: ___________________________________

                                       Title: ________________________________



                                      -2-