<PAGE>
 
RF POWER PRODUCTS, INC.
----------------------------------------

____________________________("Borrower")

has requested Mellon Bank, N.A.
                         ---------------

__________________("Bank") to make loans (the "Loans") to Borrower from time
to time during the period set forth below (the "Commitment Period") in an 
aggregate principal amount outstanding at any one time not to exceed Bank's 
commitment set forth below (the "Commitment Amount") and, subject to the terms 
and conditions set forth herein and in the Note and other Credit Documents 
(hereinafter defined) and, relying upon the representations and warranties 
herein and therein set forth, Bank is willing to make such Loans.

Commitment                           From the date hereof to but not
Period:
                                     including        May       , 1998.
                                              ------------------    --

Commitment                           The lesser of (i) $ 4,000,000.00
Amount:                                                 ----------------,
                                     or (ii) the sum of 80 % of Eligible
                                                       ---- 
                                     Accounts (as hereinafter defined)

                                     and N/A % of Eligible Inventory 
                                        -----
                                     (as hereinafter defined).

Within the limits of time and amount set forth above and subject to the terms 
and conditions set forth herein and in the Note and the other Credit Documents,
Borrower may borrow, repay and reborrow hereunder.  Borrower may at any time 
from time to time reduce the Commitment Amount to an amount not less than the 
sum of the unpaid principal amount of the Loans then outstanding plus the 
principal amount of all Loans not yet made as to which notice has been given by 
Borrower under Section 2 hereof, by providing not less than five days' prior 
written notice (which notice shall be irrevocable) to such effect to Bank.  If 
Bank allows Loans above Commitment Amount, all the terms and conditions set 
forth herein and in the Note and the other Credit Documents will apply to such 
Loans.

The obligation of Borrower to repay the Loans, to pay interest thereon and pay 
fees, if any, with respect to the Commitment Amount shall be evidenced by one or
more promissory notes, note and security agreements, letter of credit 
applications, of other instruments or documents (collectively, the "Note"), 
which together with this Agreement, including any Supplement hereto, and any 
security agreements, instruments and other documents executed by Borrower in 
connection herewith are sometimes referred to herein as the "Credit Documents".

In consideration of the foregoing and intending to be legally bound, Borrower 
agrees with Bank as follows:

1.  Representations and Warranties.  In addition to the representations and 
warranties contained in the Note and any other Credit Documents, Borrower hereby
makes the following representations and warranties which shall be true and 
correct on the date hereof and shall continue to be true and correct at the time
of the creation of any of the Loans and until the Loans shall have been paid in
full, or of there are no Loans outstanding so long as the Commitment Period has
not expired:

    (a)  Organization-Corporation and Partnership.  If Borrower is a corporation
or a partnership, Borrower is duly organized, validly existing, and in good 
standing under the laws of the jurisdiction in which Borrower is incorporated or
was formed; Borrower has the power and authority to own its properties and
assets, to carry on its businesses as now being conducted and is qualified to do
business in every jurisdiction in which it is required to qualify to do
business.

    (b)  Validity and Binding Nature.  Borrower has the power to execute, 
deliver, and perform this Agreement, the Note and all other Credit Documents, 
and when executed and delivered, this Agreement, the Note and all other Credit 
Documents will be valid and binding obligations of Borrower, enforceable in
accordance with their terms; provided, however, that this representation with
respect to enforceability is limited by bankruptcy, insolvency, or other laws of
general application relating to or affecting the enforcement of creditors'
rights.

    (c)  Due Authorization-Corporation and Partnership.  The execution, delivery
and performance of this Agreement, the Note and all other Credit Documents have 
been duly authorized by all corporate or partnership action required for the 
lawful creation and issuance and performance thereof and will not violate any 
provision of law, any order of any court or governmental agency, the charter 
documents and by-laws of, or partnership agreement of Borrower.

    (d)  Conflicting Instruments.  The execution, delivery and performance of 
this Agreement, the Note and all other Credit Documents will not violate any 
provisions of any indenture, agreement, or other instrument to which Borrower or
any of Borrower's properties or assets are bound, and will not be in conflict 
with, result in a breach of, or constitute (with due notice and/or lapse of 
time) a default under any such indenture, agreement, or other instrument, or 
result in the creation or imposition of any lien, charge or encumbrance of any 
nature whatsoever upon any of the properties or assets of Borrower.

    (e)  Authorization and Consents.  No authorization, consent, approval, 
license or exemption of, and no registration, qualification, designation, 
declaration or filing with any court or governmental department, commission, 
board, bureau, agency or instrumentality, domestic or foreign, is necessary to 
the valid execution, delivery and performance of this Agreement, the Note or any
other Credit Document.

    (f)  Financial Condition.  The most recent financial statements of Borrower 
delivered to the Bank are true and correct and represent fairly its financial
position as of the date thereof; and the results of its operations for the
period or periods indicated; and as required by GAAP, show all known
liabilities, direct or contingent, of Borrower as of the date thereof. Since the
date of such financial statements, there has been no material adverse change in
the condition, financial or otherwise, of Borrower or in the operations,
business, prospects or properties of Borrower and, since such date, Borrower has
not incurred, other than in the ordinary course of business, any indebtedness,
liabilities, obligations or commitments, contingent or otherwise, other than
indebtedness created hereunder.

    (g)  Compliance with Laws.  Neither the Borrower nor any subsidiary is in 
violation of or subject to any contingent liability on account of any law or any
order or regulation issued by any court or governmental authority, state or 
federal, including but not limited to the Employee Retirement Income Security  
Act of 1974, as amended ("ERISA"), the Internal Revenue Code of 1986, as
amended (the "Code"), any applicable occupational and health or safety law,
environmental protection or pollution control law or hazardous waste or toxic 
substances management, handling or disposal law which would have an adverse 
effect on the Borrower in excess of $100,000.

    (h)  Litigation.  Except as previously disclosed in writing to Bank prior to
the date of this Agreement, there is no action, suit or proceeding at law or in
equity or by or before any governmental instrumentality or other agency now 
pending, or to the knowledge of Borrower, threatened by or against or affecting 
Borrower or any of the properties or rights of Borrower which, if adversely 
determined, would impair the right of Borrower to carry on its business 
substantially as now conducted or would adversely affect the financial 
condition, business or operations of Borrower in an amount in excess of 
$100,000.

    (i)  Misrepresentation.  Neither this Agreement, the Note, the other Credit 
Documents, nor any other document, statement, financial statement, or
certificate furnished to Bank by or on behalf of Borrower in connection
herewith, contains an untrue statement of a material fact or omits to state a 
material fact necessary to make the statements contained therein not misleading
and, insofar as Borrower can now foresee, there is no event or condition which
may in the future materially adversely affect the financial condition,
operations or properties of Borrower which has not been set forth in this
Agreement or in a document, statement, financial statement, or certificate
furnished to Bank in connection herewith.

2.  Conditions.  The obligation of Bank to make any Loan hereunder is subject to
the performance by Borrower of its obligations to be performed hereunder and
under the Note and the other Credit Documents on or before the date of


<PAGE>
 
--------------------------------------------------------------------------------
such Loan and to the satisfaction of the following further conditions:

     (a)  The representations and warranties contained herein, in the Note and
     in the other Credit Documents shall be true on and as of the date of each
     Loan hereunder with the same effect as though made on and as of each such
     date; on each such date no "Event of Default" under and as defined in the
     Note and no event, act or condition which with notice or the passage of
     time or both would constitute such an Event of Default shall have occurred
     and be continuing or exist or shall occur or exist after giving effect to
     the Loan to be made on such date; and any request for borrowing under
     Section 2.(b) below shall constitute a certification by Borrower to both
     such effects.

     (b)  Borrower shall have provided Bank with written notice (or telephonic 
     notice confirmed in writing) of the proposed Loan specifying the principal
     amount thereof and the proposed date thereof, which notice shall be
     received by Bank at its designated office no later than 1:00 p.m., local
     time at the place where the proposed Loan is to be payable, on the date
     (which shall be a day on which Bank is opened for business) of such
     proposed Loan. Such notice shall contain a certification as to the amounts
     of the then current Eligible Accounts and Eligible Inventory. In the event
     Bank receives telephonic notice, Bank may act in reliance upon such
     telephonic notice, provided Bank has acted in good faith. 

     (c)  The conditions, if any, specified in any Supplement hereto and in the
     Note or any Credit Document shall have been met to the satisfaction of
     Bank.

     (d)  All legal details and proceedings in connection with the transactions 
     contemplated by this Agreement shall be satisfactory to Bank and Bank shall
     have received all such counterpart originals or certified or other copies
     of such documents and records of proceedings in connection with such
     transactions, in form and substance satisfactory to Bank, as Bank may from
     time to time request.

3.  General Covenants. In addition to the covenants contained in the Note and
the other Credit Documents, Borrower hereby covenants and agrees that, so long
as any of the Loans are outstanding, or if there are no Loans outstanding so
long as the Commitment Period has not expired, Borrower shall, except as Bank 
may otherwise agree in writing:

     (a)  Financial Statements-Annual. Furnish to Bank, within                
                                                               -----------------
     days after the end of each fiscal year of Borrower, a financial statement
     of Borrower's profit and loss and surplus for such fiscal year and a
     balance sheet as of the end of such fiscal year, in each case setting forth
     in comparative form the corresponding figures for the preceding fiscal
     year, all in reasonable detail and  
                                        ----------------------------------------

     See Supplement to Revolving Line of Credit Agreement
     ---------------------------------------------------------------------------

     ---------------------------------------------------------------------------

     ---------------------------------------------------------------------------

     (b)  Accounts Receivable and Inventory Reporting.  Furnish to Bank, on or 
     before the       day of each calendar month, a report, as at the end of the
                ------
     preceding calendar month, containing Borrower's account receivable aging
     and a description of raw material and finished goods inventory, including a
     listing of Eligible Accounts and Eligible Inventory, all in reasonable
     detail and in form and content satisfactory to Bank.

     (c)  Financial Statements-Other. Furnish to Bank each financial statement 
     required to be delivered to Bank by any supplement, addendum or amendment
     hereto, and such other information concerning the financial or business
     affairs of Borrower as may be requested by Bank from time to time.
     
     (d)  Property. Maintain and keep all its property in good repair, working
     order and condition and make or cause to be made all necessary or
     appropriate repairs, renewals, replacements, substitutions, additions,
     betterments and improvements thereto so that the efficiency of all such
     properties shall at all times be properly preserved and maintained.

     (e)  Taxes and Assessments. Duly pay and discharge all taxes, assessments
     and governmental charges levied upon or assessed against it or against its
     properties or income prior to the date on which penalties are attached
     thereto, unless and except to the extent only that such taxes, assessments
     and charges shall be contested in good faith and by appropriate proceedings
     diligently conducted by Borrower (unless and until foreclosure, distraint,
     sale or other similar proceedings shall have been commenced) and provided
     that such reserve or their appropriate provisions, if any, as shall be
     required by generally accepted accounting principles shall have been made
     therefor.

     (f)  Litigation. Promptly give notice in writing to Bank of the occurrence
     of any material litigation, arbitration or governmental proceeding
     affecting Borrower, and of any governmental investigation or labor dispute
     pending or, to the knowledge of Borrower, threatened which could reasonably
     be expected to interfere substantially with normal operations of the
     business of Borrower or materially adversely, affect the financial
     condition, business, or operations of Borrower.
    
     (g)  Books and Records. Maintain and keep proper records and books of
     account in conformance with generally accepted accounting principles
     applied on a consistent basis in which full, true and correct entries shall
     be made of all its dealings and business affairs.

     (h)  Access to Properties, Books and Records. Permit any of the officers,
     employees or representatives of Bank to visit and inspect any of the
     properties of Borrower and to examine its books and records and discuss the
     affairs, finances and accounts of Borrower with representatives thereof,
     during normal business hours, and as often as Bank may request.

     (i)  Financial Information-Guarantors. Cause any third party guarantor of
     the Loans to submit annually or at any time there is a material change in
     their financial position, personal or business financial statements
     containing such financial information as may be requested by Bank from time
     to time.

     (k)  Continuance of Business. Not engage in any line of business other than
     those in which it is actively engaged in on the date hereof.

     (l)  Compliance with Laws. Comply, and shall cause any subsidiary to
     comply, with all laws, and all regulations or orders issued pursuant
     thereto, including but not limited to ERISA, the Code, any applicable
     occupational, and health or safety law, environmental protection or
     pollution control law or hazardous waste or toxic substances management,
     handling or disposal law.

     (m)  Sale of Assets. Except for sales or other dispositions of inventory in
     the ordinary course of business, not sell, lease, transfer, or otherwise
     dispose of in a single transaction, or a series of related transactions,
     all or a substantial part of the property and assets of Borrower, whether
     now owned or hereafter acquired, to any person, firm or corporation.

     (n)  Acquisition of Assets. Not purchase or otherwise acquire all or
     substantially all of the operating assets of any other person, firm or
     corporation and, if Borrower is a corporation, not merge or consolidate
     with or into any other person, firm or corporation, or permit any other
     person, firm or corporation to merge with or into it, or acquire all or
     substantially all of the property or assets of any other person, firm or
     corporation.

     (o)  Selling Accounts Receivable. Not sell, assign or discount any of its
     accounts receivable or any promissory note held by it, with or without
     recourse, other than the discount of such receivables or notes in the
     ordinary course of business for collection.



<PAGE>
 
   (p) Payments on Outstanding Stock. Pursuant to or in contemplation of
   termination, liquidation, dissolution or winding up of Borrower, not
   purchase, redeem or retire or make any dividend on or distribution on account
   of, if Borrower is a corporation, any shares of the capital stock of Borrower
   or if Borrower is a partnership, any capital account of any partner of such
   partnership.

   (q) Affiliated Entities. Not establish any partnership, subsidiary,
   corporation, joint venture or other form of business combination without 
   providing prior written notice to Bank.

   (r) Insurance. Keep all insurable property, real and personal, now owned or
   hereafter acquired, insured at all times against loss or damage by fire and
   extended coverage risks and other hazards of the kinds customarily insured
   against and in amounts customarily carried by businesses engaged in
   comparable businesses and comparably situated; effect all such insurance
   under valid and enforceable policies issued by insurers of recognized
   responsibility not unacceptable to Bank, and, promptly from time to time upon
   request of Bank, deliver to Bank a summary schedule indicating all insurance
   then in effect.

   (s) Investments. Not purchase, own, invest in or otherwise acquire, directly
   or indirectly, any stock or other securities, or make or permit to exist any
   investment or capital contribution or acquire any interest whatsoever in any
   other person , firm or corporation or permit to exist any loans or advances
   for such purposes except for investments in direct obligations of the United
   States of America or any agency thereof, obligations guaranteed by the United
   States of America, certificates of deposit issued by a bank or trust company,
   organized under the laws of the United States, or any state thereof, or
   marketable securities which are publicly traded on a nationally recognized
   market.

   (t) Patents. Preserve and protect its patents, franchises, licenses,
   trademarks, trademark rights, tradenames, tradename rights, and copyrights
   used or useful in the conduct of its business.

   (u) Guarantees and Contingencies. Not endorse, assume, guarantee, become
   surety for, or otherwise become or remain liable in connection with the
   obligations of any person, firm or corporation, except Borrower may endorse
   negotiable or other instruments for deposit or collection or similar
   transactions in the ordinary course of its business.

   (v) Transactions with Affiliates. Not enter into any transaction, including,
   without limitation, the purchase, sale, leasing or exchange of property, real
   or personal, or the rendering of any service, with any person, firm or
   corporation affiliated with Borrower, except in the ordinary course of and
   pursuant to the reasonable requirements of Borrower's business and upon fair
   and reasonable terms no less favorable to Borrower than would be obtained in
   a comparable arm's-length transaction with any other person, firm or
   corporation not affiliated with Borrower.

   (w) Modifications to Other Agreements. Not amend or modify any existing
   agreement with any person, firm or corporation in any manner materially
   adverse to Borrower.

   (x) Notice of Event of Default. Promptly give notice in writing to Bank of
   the occurrence of any Event of Default under and as defined in the Note, and
   of any condition, event, act or omission which, with the giving of notice
   of the lapse of time or both, would constitute such an Event of Default.

4. General Provisions.

   (a) Waivers. The provisions of this Agreement may from time to time be waived
   in writing by Bank in its sole discretion. Any such waiver of any kind on the
   part of Bank of any breach or default under this Agreement or any waiver of
   any provision or condition of this Agreement must be in writing and shall be
   effective only to the extent set forth in such writing. No delay by Bank in
   exercising any right or remedy hereunder shall operate as a waiver thereof.

   (b) Financial Covenants. Compliance or non-compliance with all financial
   covenants of Borrower contained herein, or in any supplement, addendum or
   amendment hereto, shall be determined in accordance with generally accepted
   accounting principles applied on a consistent basis. All financial statements
   of Borrower required to be delivered to Bank hereby, or by any written
   supplement now or hereafter executed by Borrower in which reference to this
   Agreement is made, shall be prepared on the basis of generally accepted
   accounting principles applied on a consistent basis.

   (c) Binding Nature. The rights and privileges of Bank contained in this
   Agreement shall inure to the benefit of its successors and assigns, and the
   duties of Borrower shall bind all heirs, personal representatives,
   successors, and assigns. "Borrower" refers individually and collectively to
   all signers of this Agreement, including, in the case of any partnership, all
   general partners of such partnership individually and collectively, whether
   or not such partners sign below. Each of the signers shall be jointly and
   severally bound by the terms hereof, and with respect to any partnership
   executing this Agreement, each general partner shall be bound hereby both in
   such general partner's individual and partnership capacities.

   (d) Governing Law. Time of performance hereunder is of the essence of this
   Agreement. This Agreement and any written supplement hereto executed by
   Borrower in which reference to this Agreement is made shall in all respects
   be governed by the laws of the state where the Note is payable (except to the
   extent that federal law governs).

   (e) Severability. If any provision hereof shall for any reason be held
   invalid or unenforceable, no other provision shall be affected thereby, and
   this Agreement shall be construed as if the invalid or unenforceable
   provision had never been a part of it. The descriptive headings hereof are
   for convenience only and shall not in any way affect the meaning or
   construction of any provision hereof.

   (f) Definitions. i) "Eligible Accounts" shall be defined as trade accounts
                    receivable created or acquired by Borrower in the ordinary
                    course of business which are and at all times continue to be
                    acceptable to Bank and in which Bank has a Prior Security
                    Interest at all times. Standards of acceptability shall be
                    fixed and may be revised from time to time solely by Bank in
                    its exclusive judgment. As of the date hereof, accounts
                    receivable aged less than 90 days from the date of invoice
                    shall be acceptable as Eligible Accounts.

                    ii) "Eligible Inventory" shall be defined as Borrower's
                    inventory excluding work in process, of saleable raw
                    materials and finished goods manufactured or acquired by
                    Borrower in the ordinary course of business, in its sole
                    possession or control, stored in a location or locations and
                    in a manner acceptable to Bank, valued at the lower cost or
                    market value, which inventory is an at all times continues
                    to be acceptable to Bank and in which Bank has a Prior
                    Security Interest at all times. Standards of acceptability
                    shall be fixed and may be revised from time to time solely
                    by Bank in its exclusive judgment.

                    iii) "Prior Security Interest" shall be defined as an
                    enforceable, perfected security interest (under the Uniform
                    Commercial Code), which interest is senior and prior to all
                    liens (including without limitation all security interests,
                    pledges, bailments, leases, mortgages, conditional sales and
                    title retention agreements, charges, claim encumbrances,
                    judgments, levies and all other types of liens whatsoever.

5. Loans Above Commitment Amount. Notwithstanding any other provision of this
   Agreement, the Note or the other Credit Documents, if, in Bank's sole
   determination, the principal balance of the Loans hereunder shall at any time
   exceed the Commitment Amount, Borrower shall pay such excess to Bank on
   demand.

<PAGE>
 
--------------------------------------------------------------------------------
6.  Special Covenants.  In addition to the covenants contained herein and in the
Note and the other Credit Documents, Borrower hereby agrees that, so long as any
of the Loans are outstanding, or if there are no Loans outstanding so long as 
the Commitment Period has not expired, Borrower shall, except as Bank may grant 
its prior written consent, comply with the special provisions or covenants set 
forth in any written supplement, now or hereafter executed by Borrower, in which
reference to this Agreement is made.

--------------------------------------------------------------------------------
Signatures
--------------------------------------------------------------------------------

Witness the due execution hereof intending to be legally bound this 24th day of 
May, 1996.
--------------------------------------------------------------------------------
Witness:                                   Individual:
x                                          x                             (Seal)
-------------------------------------      -------------------------------------
                                           Address

-------------------------------------      -------------------------------------
Witness                                    Individual:
x                                          x                             (Seal)
-------------------------------------      -------------------------------------
                                           Address
                                           -------------------------------------
                                           Corporation or Other Entity
                                            RF POWER PRODUCTS, INC.
-------------------------------------      -------------------------------------
Attest/Witness:                            By: (Signature and Title) 
                                           Domenic Golato, CFO 
x                                          x /s/ Domenic Golato - VP+CFO (Seal) 
-------------------------------------      -------------------------------------
                                           By: (Signature and Title)

                                           x                             (Seal)
                                           -------------------------------------
                                           Business Address
(Corporate Seal)                            502 Gibbsboro-Marlton Road
                                           -------------------------------------
                                            Voorhees, NJ 08043


                                           MELLON BANK   N.A.
                                                      --------------------------

                                           -------------------------------------
                                           By: (Signature and Title)
                                           Anthony W. LaMarca, V.P.
                                           x /s/ Anthony W. LaMarca 
                                           -------------------------------------
                                           Office Address 
                                            Plymouth Meeting Executive Campus
                                           -------------------------------------
                                            610 W. Germantown Pike, Suite 200
                                            Plymouth Meeting, PA 19462
<PAGE>
 
               SUPPLEMENT TO REVOLVING LINE OF CREDIT AGREEMENT
               ------------------------------------------------

     The following constitutes the special provisions and/or special covenants 
and/or modifications referred to in the Revolving Line of Credit Agreement dated
May 24th, 1996 (the "Credit Agreement") covering the Borrowings (as that term is
defined in the Credit Agreement) of the undersigned (the "Borrower") from Mellon
Bank, N.A. ("Bank"). The following shall supercede any special provision or 
covenant contained in any prior Supplement to Revolving Line of Credit Agreement
and shall be applicable to all Borrowings in existence on the date hereof or 
incurred hereafter.

     1.  The provisions of this Supplement shall, as of the date hereof, be 
deemed to be fully incorporated by reference in, constitute a part of, and 
supplement the provisions of, the Credit Agreement, which, except as 
supplemented hereby, shall continue in full force and effect in accordance with 
its terms and conditions.

     2.  The Borrower hereby covenants and decrees that, so long as any 
Borrowings are outstanding, the Borrower shall, except as Bank may grant its 
prior written consent:

           (a)  Financial Statements-Annual.  Furnish to Bank, within ninety 
                ---------------------------
(90) days after the end of each fiscal year of the Borrower, the annual 
consolidated financial statements of the Borrower, audited and certified without
material qualification by an independent certified public accountant acceptable 
to Bank.

           (b)  Financial Statements-Quarterly.  Furnish to Bank, within 
                ------------------------------
forty-five (45) days after the end of each quarter of each fiscal year of the 
Borrower, a statement of the Borrower's profit and loss, a statement of cash 
flow and a balance sheet as of the end of such period, in each case setting 
forth in comparative form the corresponding figures from the corresponding 
period of the preceding fiscal year and comparative year-to-date presentations, 
all in reasonable detail and in a form acceptable to Bank, and prepared on an 
unaudited basis.

           (c)  Borrowing Base.  Furnish to Bank, within fifteen (15) days after
                --------------
the end of each month of the Borrower, an accounts receivable aging and a 
borrowing base certificate, each in reasonable detail and in a form acceptable 
to Bank.

           (d)  Compliance Certificate.  Together with the quarterly and annual 
                ----------------------
financial statements, furnish to Bank an Officer's Compliance Certificate,
signed by the Chief Financial Officer of the Borrower, certifying that no
default or Event of Default has occurred as of the date of such certificate and
setting forth in reasonable detail the calculations required to establish
whether the Borrower was in compliance with the applicable requirements of the
financial covenants hereof, on the date of such financial statement.









<PAGE>
 
          (e)  Certain Other Reports and Information.  Promptly upon their 
               -------------------------------------
becoming available to the Borrower, the Borrower shall deliver to Bank a copy 
of (i) all regular or special reports, registration statements and amendments to
the foregoing which the Borrower shall file with the Securities and Exchange 
Commission (or any successor thereto) or any securities exchange, (ii) all 
reports, proxy statements, financial statements and other information 
distributed by the Borrower to its stockholders, bondholders or the financial 
community generally, and (iii) all accountants' management letters pertaining 
to, all other reports submitted by accountants in connection with any audit of, 
and all other material reports from outside accountants with respect to, the 
Borrower.

          (f)  Negative Pledge.  Not incur, create, assume or permit to exist, 
               ---------------
any mortgage, pledge, lien, charge or other encumbrance of any nature whatsoever
on any of the assets of the Borrower, whether now or hereafter owned, other than
(i) security interests granted in favor of Bank, (ii) pledges or deposits under
workers' compensation, unemployment insurance and social security laws, or to 
secure the performance of bids, tenders, contracts (other than for the repayment
of borrowed money) or leases or to secure statutory obligations or surety or 
other similar bonds used in the ordinary course of business, (iii) tax liens 
which are being contested in good faith and by appropriate proceedings 
diligently conducted (unless and until foreclosure, sale or other similar 
proceedings have been commenced) and provided that such reserve or other 
appropriate provisions, if any, as shall be required by GAAP shall have been 
made therefor, and (iv) any unfiled materialmen's, mechanic's, workmen's and 
repairmen's liens (provided, that if such a lien shall be perfected, it shall 
be discharged of record immediately by payment, bond or otherwise).

          (g)  Additional Indebtedness.  Not create or incur any additional 
               -----------------------
indebtedness except loans from Bank and any term loans from the New Jersey 
Economic Development Authority which in aggregate do not exceed $500,000.

          (h)  Financial Covenants.  Comply with the following financial 
               -------------------
covenants which shall be tested on the Borrower on a quarterly basis and in 
accordance with GAAP:

               (i)  Leverage Ratio.  The Borrower's ratio of (a) total 
                    --------------
liabilities, determined in accordance with GAAP, divided by (b) Tangible Net 
                                                 ----------
Worth, shall not exceed 1.25 to 1.00.

               (ii)  Cash Flow Ratio.  The Borrower's ratio of (a) Cash Flow to
                     ---------------
(b) current maturities on long term debt (including capitalized leases and as 
determined in accordance with GAAP) which were reported on the balance sheet of
the Borrower for the period ending one year prior to the calculation date, plus
                                                                           ----
capital expenditures, as measured on a rolling four-quarter basis and as
determined in accordance with GAAP, shall not be less than 1.25 to 1.00 as
measured as of the fiscal quarters ending May 31, 1996,



                                      -2-
<PAGE>
 
August 31, 1996 and November 30, 1996, and shall not be less than 1.50 to 1.00 
at any fiscal quarter end thereafter.

          (i)  Management. The Borrower shall retain capable executive 
               ----------
management personnel at all times satisfactory to Bank, it being understood that
the management personnel of the Borrower as of the date hereof is satisfactory 
to Bank.

     3.  Conditions to Initial Loans. The obligation of Bank to make loans on 
         ---------------------------
the date hereof is subject to the satisfaction, immediately prior to or 
concurrently with the making of any Borrowing, of the following conditions:

          (a)  All documentation, instruments, and proceedings shall be 
satisfactory to Bank;

          (b)  No material adverse change shall have occurred in the business, 
products or prospects of the Borrower;

          (c)  The Borrower shall provide Bank with evidence that the Borrower 
has purchased and currently maintains policies of insurance, satisfactory to 
Bank and designating Bank as the loss payee, to protect the personal property 
pledged as collateral to Bank;

          (d)  No material adverse change shall have occurred in the financial 
condition of the Borrower, as such financial condition was depicted in the 
Borrower's financial statements dated November 30, 1995 and February 29, 1996.

          (e)  The Borrower will provide Bank with an option of counsel for the 
Borrower regarding the execution, delivery, validity and enforceability of the 
loan documents and the liens granted thereto.

     4.  Adoption of Certain Terms or Covenants. The Borrower shall give notice 
         --------------------------------------
in writing to Bank of the occurrence of any default under any debt instruments 
or under any material contractual obligations or agreements with governmental 
authorities, and of the incurrence of new or additional debt obligations and the
terms thereof, and of any change, whether by addition or modification in the 
terms or covenants of any debt obligation. In the event that the terms or 
covenants of any debt obligation of the Borrower existing on the date hereof or 
incurred by the Borrower subsequent to the date hereof are more restrictive than
the terms and covenants of the Credit Agreement, such terms and covenants shall 
be deemed to be incorporated into the Credit Agreement for the benefit of Bank 
and shall be binding upon the Borrower and enforceable by Bank hereunder, at its
discretion, as if such more restrictive terms and conditions were herein fully 
set forth.

     5.  Definitions.  In addition to other words and terms defined elsewhere in
         -----------
the Credit Agreement, as used herein, the following words and terms shall have 
the following meanings:

                                      -3-
<PAGE>
 
          (a)  "Cash Flow" means net income minus dividends or withdrawals plus 
                ---------                   -----                          ----
depreciation and amortization, as measured on a rolling four-quarter basis and 
as determined in accordance with GAAP.

          (b)  "GAAP" means generally accepted accounting principals of the 
                ----
United States of America.


          (c)  "Tangible Net Worth" shall mean shareholders' equity less 
                ------------------                                  ----
intangible assets, each determined in accordance with GAAP.

     Witness the due execution hereof intending to be legally bound this 24th 
                                                                         ----
day of May, 1996.


ATTEST:                                     RF POWER PRODUCTS, INC.


/s/ Paul S. Zaun                            By: /s/ Domenic N. Golato
--------------------------------               --------------------------------
By: Paul S. Zaun                               Domenic N. Golato
Title: Director Cost Accounting                Chief Financial Officer


                                            MELLON BANK, N.A.

                                            Accepted by:

                                            /s/ Anthony W. LaMarca
                                            -----------------------------------
                                            Anthony W. LaMarca
                                            Vice President



                                      -4-
<PAGE>
 
             FIRST AMENDMENT TO REVOLVING LINE OF CREDIT AGREEMENT
             -----------------------------------------------------

         THIS FIRST AMENDMENT TO REVOLVING LINE OF CREDIT AGREEMENT (this
"Agreement") made as of this 17th day of January, 1997 between RF POWER
PRODUCTS, INC. a New Jersey corporation (the "Borrower"), and MELLON BANK, N.A.,
a national banking association (the "Bank").


                             W I T N E S S E T H:

         WHEREAS, the Borrower and the Bank are parties to a Revolving Line of
Credit Agreement dated May 24th, 1996 (the "Credit Agreement"), pursuant to
which the Bank agreed to extend to the Borrower a Four Million Dollar
($4,000,000) revolving credit facility (capitalized terms used herein but not
defined in this Agreement shall have the meaning ascribed to them in the Credit
Agreement);

         WHEREAS, the Borrower has requested that the Bank amend certain 
provisions of the Credit Agreement in order to, among other things, gain 
permission to obtain equipment financing in the amount of $500,000; and

         WHEREAS, the Bank is willing to grant such request, subject to the 
terms and conditions of this Agreement.

         NOW, THEREFORE, in consideration of the mutual promises contained 
herein and intending to be legally bound, the Borrower and the Bank hereby 
covenant and agree as follows:

         1.  Amendments.  Upon the execution and delivery by the Borrower and 
             ----------
the Bank of this Agreement and the First Amendment to Note and Security
Agreement dated of even date herewith, (the "Note Amendment"), the Credit
Agreement shall be amended as follows:

         (a)  The Supplement to Revolving Line of Credit Agreement (the
"Supplement") shall be amended by deleting Section 2(f) in its entirety and
replacing it with the following:

              (f)  Negative Pledge.  Not incur, create, assume or permit to
                   ---------------
         exist, any mortgage, pledge, lien, charge or other encumbrance of any
         nature whatsoever on any of the assets of the Borrower, whether now or
         hereafter owned, other than (i) security interests granted in favor of
         Bank, (ii) security interests granted in favor of the New Jersey
         Economic Development Corporation to secure equipment purchases in an
         amount not to exceed $500,000, (iii) pledges or deposits under workers'
         compensation, unemployment insurance and social security laws, or to
         secure the performance of bids, tenders, contracts (other than for the
         repayment of borrowed money) or leases or to secure statutory
         obligations or surety or other similar bonds used in the ordinary
         course of business, (iv) tax liens which are being contested in good

<PAGE>
 
    faith and by appropriate proceedings diligently conducted (unless and until 
    foreclosure, sale or other similar proceedings have been commenced) and
    provided that such reserve or other appropriate provisions, if any, as shall
    be required by GAAP shall have been made therefor, and (v) any unfiled
    materialmen's, mechanic's, workmen's and repairmen's liens (provided, that
    if such a lien shall be perfected, it shall be discharged or record
    immediately by payment, bond or otherwise).

        (b) Section 2(h) of the Supplement, Financial Covenants, shall also be
                                            --------- ---------
further amended by adding the following additional provision as Subsection 
2(h)(iii):

            (iii) Minimum Tangible Net Worth.  The Tangible Net Worth of the 
                  --------------------------
Borrower shall be greater than or equal to the following amounts as of the 
following dates:

Fiscal Quarters Ending                          Tangible Net Worth
----------------------                          ------------------

  February 28, 1997 and                         $7,800,000
     May 31, 1997

  August 31, 1997                               $8,000,000

  November 30, 1997                             $8,500,000

  All times thereafter                          No requirement

        (c) The Credit Agreement shall be amended to reflect that references in 
the Credit Agreement to the "Note" shall be references to the Note and Security 
Agreement as amended by the Note Amendment and as may be still further amended, 
modified or supplemented from time to time.

        2.  One-Time Covenant Waiver.  The Bank hereby agrees that it shall not 
            ------------------------
measure the Cash Flow Ratio covenant set forth in Section 2(h)(ii) of the 
Supplement for the fiscal quarters ending February 28, 1997, May 31, 1997, 
August 31, 1997 or November 30, 1997.  However, the Borrower specifically 
acknowledges that the waiver of such covenant compliance represents a one-time 
only, limited waiver and that the covenant shall be measured again beginning 
with the fiscal quarter ending February 28, 1998, and shall not be less than 
1.50 to 1.00 as of such date and as of each fiscal quarter thereafter.

        3.  Representations and Warranties.  The Borrower hereby represents and 
            ------------------------------
warrants to the Bank that the Borrower is not in default under the Note, the 
Credit Agreement or any other document executed in connection therewith.

        4.  Other Terms Confirmed.  All other terms and conditions of the Credit
            ---------------------
Agreement, including, without limitation, the Supplement attached thereto, are 
hereby confirmed and shall remain in full force and effect without modification.
From and 

                                                                         path-2-

<PAGE>
 
after the effectiveness of the amendments set forth in Section 1 hereof, all 
references in any document or instrument to the Credit Agreement shall mean the 
Credit Agreement as amended by this Agreement.

        5.  No New Indebtedness.  The Borrower specifically acknowledges and 
            -------------------
agrees that this Agreement shall not represent in any way the extension of any
new credit by the Bank to the Borrower, or the satisfaction of any indebtedness
evidenced by the Credit Agreement as amended hereby or the Note.

        6.  Counterparts.  This Agreement may be executed in any number of 
            ------------
counterparts, each of which shall be deemed an original, but all such 
counterparts together shall constitute but one and the same instrument.

        7.  Headings.  The descriptive headings which are used in this Agreement
            --------
are for convenience only and shall not affect the meaning of any provision of 
this Agreement.

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

Attest:                                         RF POWER PRODUCTS, INC.


[SIGNATURE APPEARS HERE]                        /s/ Domenic N. Golato
-----------------------------                   ------------------------------
Name:                                           By:  Domenic N. Golato
Title:                                               Chief Financial Officer

[Corporate Seal]                                MELLON BANK, N.A.



                                                By: /s/ Anthony W. LaMarca
                                                   ---------------------------
                                                   Anthony W. LaMarca
                                                   Vice President



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