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                                                                   EXHIBIT 10.75

                                  P-Com, Inc.
                                 PROMISSORY NOTE

November 16, 1999                                                       $400,000

            P-Com, Inc., a Delaware corporation (the "Company"), hereby promises
to pay to the order of Castle Creek Technology Partners LLC the principal amount
of $400,000 together with interest thereon calculated from the date hereof in
accordance with the provisions of this Note.

            This Note was issued pursuant to a Penalty Settlement Agreement,
entered into as of November 16, 1999 (as amended and modified from time to time,
the "Agreement"), between the Company and the original holder of this Note.

            1. Payment of Interest. Except as otherwise expressly provided in
paragraph 3(b) hereof, interest shall accrue at the rate of twelve percent (12%)
per annum on the unpaid principal amount of this Note outstanding from time to
time, or (if less) at the highest rate then permitted under applicable law. The
Company shall pay to the holder of this Note all accrued interest on the date
the principal amount of this Note is due (whether at maturity or otherwise).
Unless prohibited under applicable law, any accrued interest which is not paid
on the date on which it is due and payable shall bear interest at the same rate
at which interest is then accruing on the principal amount of this Note until
such interest is paid. Interest shall accrue on any principal payment due under
this Note and, to the extent permitted by applicable law, on any interest which
has not been paid on the date on which it is due and payable until such time as
payment therefore is actually delivered to the holder of this Note.

            2. Payment of Principal on Note.

                  (a) Scheduled Payments. The Company shall pay the principal
amount of $400,000 (or such lesser principal amount then outstanding) to the
holder of this Note on November 15, 2000, together with all accrued and unpaid
interest on the principal amount being repaid.

                  (b) Prepayments. The Company may not prepay this Note without
the prior written consent of the Holder which may be withheld for any or no
reason. In connection with each prepayment of principal hereunder, the Company
shall also pay all accrued and unpaid interest to the date of prepayment on the
principal amount of this Note being repaid.

            3. Events of Default.

                  (a) Definition. For purposes of this Note, an Event of Default
shall be deemed to have occurred if:

                        (i) the Company fails to pay when due and payable
(whether at maturity or otherwise) the full amount of interest then accrued on
this Note or the full amount of any principal payment on this Note;


                                  Exhibit A-1
<PAGE>

                        (ii) the Company fails to perform or observe any other
material provision contained in this Note or in the Agreement, and such failure
is not cured within 5 days after the occurrence hereof;

                        (iii) any representation, warranty or information
contained in the Agreement is false or misleading in any material respect on the
date made;

                        (iv) the Company or any subsidiary makes an assignment
for the benefit of creditors or admits in writing its inability to pay its debts
generally as they become due; or an order, judgment or decree is entered
adjudicating the Company or any subsidiary bankrupt or insolvent; or any order
for relief with respect to the Company or any subsidiary is entered under the
Federal Bankruptcy Code; or the Company or any subsidiary petitions or applies
to any tribunal for the appointment of a custodian, trustee, receiver or
liquidator of the Company or any subsidiary, or of any substantial part of the
assets of the Company or any subsidiary, or commences any proceeding (other than
a proceeding for the voluntary liquidation and dissolution of any subsidiary)
relating to the Company or any subsidiary under any bankruptcy reorganization,
arrangement, insolvency, readjustment of debt, dissolution or liquidation law of
any jurisdiction; or any such petition or application is filed, or any such
proceeding is commenced, against the Company or any subsidiary and either (A)
the Company or any such subsidiary by any act indicates its approval thereof,
consent thereto or acquiescence therein or (B) such petition, application or
proceeding is not dismissed within 60 days;

                        (v) a judgment in excess of $250,000 is rendered against
the Company or any subsidiary and, within 60 days after entry thereof, such
judgment is not discharged in full or execution thereof stayed pending appeal,
or within 60 days after the expiration of any such stay, such judgment is not
discharged in full; or

                        (vi) the Company or any subsidiary defaults in the
performance of any obligation if the effect of such default is to cause an
amount exceeding $250,000 to become due prior to its stated maturity or to
permit the holder or holders of such obligation to cause an amount exceeding
$250,000 to become due prior to its stated maturity.

            The foregoing shall constitute Events of Default whatever the reason
or cause for any such Event of Default and whether it is voluntary or
involuntary or is effected by operation of law or pursuant to any judgment,
decree or order of any court or any order, rule or regulation of any
administrative or governmental body.

                  (b) Consequences of Events of Default.

                        (i) If any Event of Default has occurred the interest
rate on this Note shall increase immediately to the lesser of 18% or the highest
interest rate permitted by law.

                        (ii) If an Event of Default of the type described in
subparagraph 3(a)(iv) has occurred, the aggregate principal amount of this Note
(together with all accrued interest thereon and all other amounts due and
payable with respect thereto) shall become immediately due and payable without
any action on the part of the holders of this Note, and the Company shall
immediately pay to the holders of this Note all amounts due and payable with
respect to this Note.


                                  Exhibit A-2
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                        (iii) If any Event of Default has occurred (other than
under subparagraph 3(a)(iv)), the holder of this Note may declare all or any
portion of the outstanding principal amount of this Note (together with all
accrued interest thereon and all other amounts due and payable with respect
thereto) to be immediately due and payable and may demand immediate payment of
all or any portion of the outstanding principal amount of this Note (together
with all such other amounts then due and payable).

                        (iv) The holder of this Note shall also have any other
rights which such holder may have been afforded under any contract or agreement
at any time and any other rights which such holder may have pursuant to
applicable law.

                        (v) The Company hereby waives diligence, presentment,
protest and demand and notice of protest and demand, dishonor and nonpayment of
this Note, and expressly agrees that this Note, or any payment hereunder, may be
extended from time to time and that the holder hereof may accept security for
this Note or release security for this Note, all without in any way affecting
the liability of the Company hereunder.

            4. Amendment and Waiver. Except as otherwise expressly provided
herein, the provisions of this Note may be amended and the Company may take any
action herein prohibited, or omit to perform any act herein required to be
performed by it, only if the Company has obtained the written consent of the
holder of this Note.

            5. Payments. All payments to be made to the holder of this Note
shall be made in the lawful money of the United States of America in immediately
available funds.

            6. Place of Payment. Payments of principal and interest shall be
paid by wire transfer of immediately available funds to an account designated by
the holder of this Note.

            7. Business Days. If any payment is due, or any time period for
giving notice or taking action expires, on a day which is a Saturday, Sunday or
legal holiday in the State of New York, the payment shall be due and payable on,
and the time period shall automatically be extended to, the next business day
immediately following such Saturday, Sunday or legal holiday, and interest shall
continue to accrue at the required rate hereunder until any such payment is
made.

            8. Conversion.

                  (a) The Holder may, at any time and from time to time, convert
all or any part of this Note into fully paid and non-assessable shares of common
stock of the Company by delivery of a conversion notice to the Company. The
effective date of any conversion shall be the date of the conversion notice.
Upon any conversion the Company will within three business days of receipt of
this Note and the conversion notice, issue to the Holder such number of shares
of common stock equal to (i) the principal amount of this Note being converted
plus all accrued and unpaid interest thereon divided by (ii) $4.715625 (the
"Conversion Price"). If the Note is converted for less than the full amount of
principal, the Company shall cancel the original Note and issue to the Holder a
new Note, of like tenor, for the remaining principal balance.


                                  Exhibit A-3
<PAGE>

                  (b) The Company shall pay any and all taxes (other than
transfer taxes) which may be imposed with respect to the issuance and delivery
of the shares of common stock upon the conversion of this Note.

                  (c) No fractional shares of common stock are to be issued upon
the conversion of this Note, but the Company shall instead round up to the next
whole number the number of shares of common stock to be issued upon such
conversion.

                  (d) Notwithstanding anything to the contrary contained herein,
this Note shall not be convertible by a Holder to the extent (but only to the
extent) that, if convertible by such Holder, such Holder would beneficially own
in excess of 4.9% (the "Applicable Percentage") of the shares of common stock.
To the extent the above limitation applies, the determination of whether this
Note shall be exercisable (vis-a-vis other securities owned by Holder which
contain similar limitations on conversion) shall be made on the basis of the
earliest submission of this Note (vis-a-vis other securities owned by the Holder
which contain similar limitations on conversion), in each case subject to such
aggregate percentage limitation. No prior inability to convert this Note
pursuant to this paragraph shall have any effect on the applicability of the
provisions of this paragraph with respect to any subsequent determination of
convertibility. For the purposes of this paragraph, beneficial ownership and all
determinations and calculations, including without limitation, with respect to
calculations of percentage ownership, shall be determined in accordance with
Section 13(d) of the Securities Exchange Act of 1934, as amended, and Regulation
13D and G thereunder. The provisions of this paragraph may be implemented in a
manner otherwise than in strict conformity with the terms of this Section with
the approval of the Board of Directors of the Company and the Holder: (i) with
respect to any matter to cure any ambiguity herein, to correct this paragraph
(or any portion hereof) which may be defective or inconsistent with the intended
Applicable Percentage beneficial ownership limitation herein contained or to
make changes or supplements necessary or desirable to properly give effect to
such Applicable Percentage limitation; and (ii) with respect to any other
matter, with the further consent of the holders of a majority of the then
outstanding shares of common stock. For clarification, it is expressly a term of
this security that the limitations contained in this Section shall apply to each
successor Holder.

            9. Stock Splits, Stock Dividends, Etc. If at any time on or after
the date of issuance of this Note, the number of outstanding shares of Common
Stock is increased by a stock split, stock dividend, combination,
reclassification or other similar event, Conversion Price shall be
proportionately reduced, or if the number of outstanding shares of common stock
is decreased by a reverse stock split, combination or reclassification of
shares, or other similar event, the Conversion Price shall be proportionately
increased. In such event, the Company shall notify the Company's transfer agent
of such change on or before the effective date thereof.

            10. Adjustment Due to Distribution. If the Company shall declare or
make any distribution of its assets (or rights to acquire its assets) to holders
of common stock as a partial liquidating dividend, by way of return of capital
or otherwise (including any dividend or distribution to the Company's
shareholders in cash or shares (or rights to acquire shares) of capital stock of
a subsidiary) (a "Distribution") at any time, then the Holder shall be entitled,
upon any conversion of this Note after the date of record for determining
shareholders entitled to such Distribution, to receive the amount of such assets
(or rights) which would have been


                                  Exhibit A-4
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payable to the Holder had the Holder with respect to the shares of common stock
issuable upon such conversion (without regard to any limitations on conversion
or exercise herein or elsewhere contained) been the holder of such shares of
common stock on the record date for the determination of shareholders entitled
to such Distribution.

            11. Purchase Rights. If the Company issues any securities or rights
to purchase stock, warrants, securities or other property (the "Purchase
Rights") pro rata to the record holders of any class of common stock, then the
Holders will be entitled to acquire, upon the terms applicable to such Purchase
Rights, the aggregate Purchase Rights which each Holder could have acquired if
such Holder had held the number of shares of common stock acquirable upon
complete conversion of this Note (without regard to any limitations on
conversion or exercise herein or elsewhere contained) immediately before the
date on which a record is taken for the grant, issuance or sale of such Purchase
Rights, or, if no such record is taken, the date as of which the record holders
of common stock are to be determined for the grants, issue or sale of such
Purchase Rights.

            12. Governing Law. All issues and questions concerning the
construction, validity, enforcement and interpretation of this Note shall be
governed by, and construed in accordance with, the laws of the State of New
York, without giving effect to any choice of law or conflict of law rules or
provisions (whether of the State of New York or any other jurisdiction) that
would cause the application of the laws of any jurisdiction other than the State
of New York.

            13. Application of Payments. All payments shall be applied first, to
accrued and unpaid interest on the unpaid principal balance of this Note and
then to the unpaid principal balance of this Note.

            14. Late Charge. If a payment of principal or interest to be made
pursuant to this Note becomes past due for a period in excess of 5 days, The
Company shall pay on demand to the Holder a late charge of 2% of the amount of
such overdue payment.

            15. Costs of Collection. If any suit or action is instituted or
attorneys are employed to collect this Note or any part hereof, the Company
promises and agrees to pay all costs of collection, including all court costs
and reasonable attorneys' fees based upon customary hourly rates and not a
percentage of the indebtedness outstanding.

            16. WAIVER OF JURY TRIAL. THE COMPANY ACKNOWLEDGES AND AGREES THAT
ANY CONTROVERSY WHICH MAY ARISE UNDER THIS NOTE WOULD BE BASED UPON DIFFICULT
AND COMPLEX ISSUES AND THEREFORE, THE COMPANY AGREES THAT ANY COURT PROCEEDING
ARISING OUT OF ANY SUCH CONTROVERSY WILL BE TRIED IN A COURT OF COMPETENT
JURISDICTION BY A JUDGE SITTING WITHOUT A JURY.

            The Company has executed and delivered this Note on November 16,
1999.

                                       P-COM, INC.


                                       By: /s/ Robert E. Collins
                                           -------------------------------------
                                       Its: Robert E. Collins
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                                  Exhibit A-5