EXHIBIT 10.4

NEITHER THIS CONVERTIBLE PROMISSORY NOTE NOR THE VOTING COMMON STOCK INTO WHICH
IT IS CONVERTIBLE HAS BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR ANY APPLICABLE STATE SECURITIES LAWS. THEY MAY NOT BE SOLD, OFFERED
FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF A REGISTRATION STATEMENT IN
EFFECT WITH RESPECT TO THE SECURITIES UNDER SUCH ACT AND APPLICABLE LAWS OR SOME
OTHER EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF SUCH ACT AND APPLICABLE
LAWS OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION
IS NOT REQUIRED.

                            PINNACLE TOWERS III INC.
                           CONVERTIBLE PROMISSORY NOTE

$826,005                                                        January 27, 2000
                                                              New York, New York

         PINNACLE TOWERS III INC., a Florida corporation (the "Company"), the
principal office of which is located at 1549 Ringling Boulevard, Third Floor,
Sarasota, Florida 34236, for value received hereby promises to pay to Pinnacle
Towers Inc., or its registered assigns, the sum of Eight Hundred Twenty-six
Thousand Five Dollars ($826,005), or such lesser amount as shall then equal the
outstanding principal amount hereof and any unpaid accrued interest hereon, as
set forth below. The outstanding principal under this Note shall be due and
payable in full within 30 days of the date demand is made therefor by the
Holder. Demand under this Note shall be given by the Holder to the Company by
written notice thereof in accordance with Section 11 below. Payment for all
amounts due hereunder shall be made at the Company's option by either wire
transfer or by mail to the registered address of the Holder.

         The following is a statement of the rights of the Holder of this Note
and the conditions to which this Note is subject, and to which the Holder
hereof, by the acceptance of this Note, agrees:

         1. Definitions. As used in this Note, the following terms, unless the
context otherwise requires, have the following meanings:

            (a) "Company" includes any corporation which shall succeed to or
assume the obligations of the Company under this Note.

            (b) "Holder," when the context refers to a holder of this Note,
shall mean any Person who shall at the time be the registered holder of this
Note.

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            (c) "Person" means any individual, Company, partnership, joint
venture, trust, unincorporated organization or government or any agency or
political subdivision thereof.

         2. Interest. Commencing on March 31, 2000, and on each June 30,
September 30, December 31 and March 31 thereafter until all outstanding
principal and interest on this Note shall have been paid in full, the Company
shall pay interest at the rate of thirteen percent (13%) per annum (the "Initial
Interest Rate") on the principal of this Note outstanding during the period
beginning on the date of issuance of this Note and ending on the date that the
principal amount of this Note becomes due and payable. In the event that the
principal amount of this Note is not paid in full when such amount becomes due
and payable, interest at the same rate as the Initial Interest Rate plus two
percent (2%) shall continue to accrue on the balance of any unpaid principal
until such balance is paid.

         3. Conversion.

            3.1 Conversion. Any Holder of this Note has the right, at the
Holder's option (the "Option"), at any time prior to payment in full of the
principal balance of this Note, to convert this Note, in accordance with the
provisions of Section 3.2 hereof, in whole or in part, into fully paid and
nonassessable shares of the Company's Voting Common Stock, par value $0.001 per
share or Nonvoting Common Stock, par value $0.001 per share (the "Common
Stock"), at the option of the Holder from time to time. The number of shares of
Common Stock into which this Note may be converted ("Conversion Shares") shall
be determined by dividing the aggregate principal amount of this Note together
with all accrued interest to the date of conversion elected to be converted by
the Holder by the Conversion Price (as defined below) in effect at the time of
such conversion. The initial Conversion Price shall be equal to $25 (the
"Conversion Price").

            3.2 Notice of Conversion Pursuant to Section 3.1. Before the Holder
shall be entitled to convert this Note into shares of Common Stock, it shall
surrender this Note at the office of the Company and shall give written notice
to the Company at its principal corporate office of the election to convert all
or a portion of the same pursuant to this Section 3 ("Notice of Conversion"),
and shall state therein the amount of the Note to be converted and the name or
names in which the certificate or certificates for shares of Common Stock are to
be issued. Such conversion shall be deemed to have been made immediately prior
to the close of business on the date of such surrender of the Note, and the
Person or Persons entitled to receive the shares of Common Stock issuable upon
such conversion shall be treated for all purposes as the record holder or
holders of such shares of Common Stock as of such date.

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            3.3 Mechanics and Effect of Conversion. No fractional shares of
Common Stock shall be issued upon conversion of this Note. In lieu of the
Company issuing any fractional shares to the Holder upon the conversion of this
Note, the Company shall pay to the Holder the amount of outstanding principal
that is not so converted, such payment to be in the form as provided below. Upon
the conversion of this Note pursuant to Section 3.1 above, the Holder shall
surrender this Note, duly endorsed, at the principal office of the Company. At
its expense, the Company shall, as soon as practicable thereafter, issue and
deliver to such Holder at such principal office a certificate or certificates
for the number of shares of such Common Stock to which the Holder shall be
entitled upon such conversion (bearing such legends as are required by
applicable state and federal securities laws in the opinion of counsel to the
Company), together with any other securities and property to which the Holder is
entitled upon such conversion under the terms of this Note, including a check
payable to the Holder for any cash amounts payable as described above and a
replacement Note representing any amount of the Note not converted. Upon the
complete conversion of all of this Note, the Company shall be forever released
from all its obligations and liabilities under this Note, except that the
Company shall be obligated to pay the Holder, within ten (10) days after the
date of such conversion, any interest accrued and unpaid or unconverted to and
including the date of such conversion, and no more.

         4. Prepayment. Prepayment of the principal of this Note is permitted,
in whole or in part, without premium or penalty of any kind; provided the
Company provides the Holder with thirty (30) days' prior written notice (unless
notice is waived in writing by the Holder) of its intention to prepay the
principal of this Note, in whole or in part, during which time the Holder may
exercise the Option by delivering to the Company the Notice of Conversion.

         5. Conversion Price Adjustments.

            5.1 Adjustments for Stock Splits and Subdivisions. In the event the
Company should at any time or from time to time after the date of issuance
hereof fix a record date for the effectuation of a split or subdivision of the
outstanding shares of Common Stock or the determination of holders of Common
Stock entitled to receive a dividend or other distribution payable in additional
shares of Common Stock or other securities or rights convertible into, or
entitling the holder thereof to receive directly or indirectly, additional
shares of Common Stock (hereinafter referred to as "Common Stock Equivalents")
without payment of any consideration by such holder for the additional shares of
Common Stock or the Common Stock Equivalents (including the additional shares of
Common Stock issuable upon conversion or exercise thereof), then, as of such
record date (or the date of such dividend distribution, split or subdivision if
no record date is fixed), the Conversion

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Price of this Note shall be appropriately decreased so that the number of shares
of Common Stock issuable upon conversion of this Note shall be increased in
proportion to such increase of outstanding shares.

            5.2 Adjustments for Reverse Stock Splits. If the number of shares of
Common Stock outstanding at any time after the date hereof is decreased by a
combination of the outstanding shares of Common Stock, then, following the
record date of such combination, the Conversion Price for this Note shall be
appropriately increased so that the number of shares of Common Stock issuable on
conversion hereof shall be decreased in proportion to such decrease in
outstanding shares.

            5.3 Notices of Record Date, etc. In the event of:

                (a) Any taking by the Company of a record of the holders of any
class of securities of the Company for the purpose of determining the holders
thereof who are entitled to receive any dividend (other than a cash dividend
payable out of earned surplus at the same rate as that of the last such cash
dividend theretofore paid) or other distribution, or any right to subscribe for,
purchase or otherwise acquire any shares of stock of any class or any other
securities or property, or to receive any other right; or

                (b) Any capital reorganization of the Company, any
reclassification or recapitalization of the capital stock of the Company or any
transfer of all or substantially all of the assets of the Company to any other
Person or any consolidation or merger involving the Company; or

                (c) Any voluntary or involuntary dissolution, liquidation or
windingup of the Company, the Company will mail to the holder of this Note at
least seven (7) days prior to the earliest date specified therein, a notice
specifying:

                    (i) The date on which any such record is to be taken for the
purpose of such dividend, distribution or right, and the amount and character of
such dividend, distribution or right; and

                    (ii) The date on which any such reorganization,
reclassification, transfer, consolidation, merger, dissolution, liquidation or
windingup is expected to become effective and the record date for determining
shareholders entitled to vote thereon.

            5.4 Reservation of Stock Issuable Upon Conversion. The Company shall
at all times reserve and keep available out of its authorized but unissued
shares of Common Stock solely for the purpose of effecting the conversion of
this Note such number of its shares of Common Stock as shall from time to time
be

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sufficient to effect the conversion of the Note; and if at any time the number
of authorized but unissued shares of Common Stock shall not be sufficient to
effect the conversion of the entire outstanding principal amount of this
Note, in addition to such other remedies as shall be available to the holder of
this Note, the Company will use its best efforts to take such corporation action
as may, in the opinion of its counsel, be necessary to increase its authorized
but unissued shares of Common Stock to such number of shares as shall be
sufficient for such purposes.

        6.  Representations and Warranties of the Holder.

            (a) The Holder by its acceptance of this Note acknowledges that it
is aware that this Note and the shares of Common Stock issuable to it by the
Company upon conversion of this Note have not been registered under the
Securities Act of 1933, as amended ("Act"), or the securities laws of any state
or other jurisdiction.

            (b) The Holder warrants and represents to the Company that it has
acquired this Note, and, upon conversion of the Note, it will be acquiring the
Common Stock, for investment and not with a view to or for sale in connection
with any distribution of this Note or such Common Stock or with any intention of
distributing or selling this Note or such Common Stock.

            (c) The Holder has no right to demand that the Company register this
Note or the shares of Common Stock issued or issuable under this Note.

         7. Assignment. Subject to the restrictions on transfer described in
Section 11 below, the rights and obligations of the Company and the Holder of
this Note shall be binding upon and benefit the successors, assigns, heirs,
administrators and transferees of the parties.

         8. Waiver and Amendment. Any provision of this Note may be amended,
waived or modified upon the written consent of the Company and the Holder.

         9. Transfer of This Note or Securities Issuable on Conversion Hereof.
With respect to any offer, sale or other disposition of this Note or securities
into which such Note may be converted, the Holder will give written notice to
the Company prior thereto, describing briefly the manner thereof, together with
a written opinion of such Holder's counsel, to the effect that such offer, sale
or other distribution may be effected without registration or qualification
(under any federal or state law then in effect). Promptly upon receiving such
written notice and reasonably satisfactory opinion, if so requested, the
Company, as promptly as practicable, shall notify such Holder that such Holder
may sell or otherwise dispose of this Note or such securities, all in accordance
with the terms of the notice delivered to the Company. If a determination has
been made pursuant to this

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Section 9 that the opinion of counsel for the Holder is not reasonably
satisfactory to the Company, the Company shall so notify the Holder promptly
after such determination has been made. Each Note thus transferred and each
certificate representing the securities thus transferred shall bear a legend as
to the applicable restrictions on transferability in order to ensure compliance
with the Act, unless in the opinion of counsel for the Company such legend is
not required. The Company may issue stop transfer instructions to its transfer
agent in connection with such restrictions.

         10. Treatment of Note. To the extent permitted by generally accepted
accounting principles, the Company will treat, account and report the Note as
debt and not equity for accounting purposes and with respect to any returns
filed with federal, state or local tax authorities.

         11. Notices. Any notice, request or other communication required or
permitted hereunder shall be in writing and shall be deemed to have been duly
given if personally delivered or if (and then two business days after) mailed by
registered or certified mail, postage prepaid, at the respective addresses of
the parties as set forth herein. Any party hereto may by notice so given change
its address for future notice hereunder.

         12. No Shareholder Rights. Nothing contained in this Note shall be
construed as conferring upon the Holder or any other Person the right to vote or
to consent or to receive notice as a shareholder in respect of meetings of
shareholders for the election of directors of the Company or any other matters
or any rights whatsoever as a shareholder of the Company; and no dividends or
interest shall be payable or accrued in respect of this Note or the interest
represented hereby or the Conversion Shares obtained hereunder until, and only
to the extent that, this Note shall have been converted.

         13. Governing Law. This Agreement shall be governed by and construed in
accordance with the laws of the State of Florida, excluding that body of law
relating to conflict of laws.

         14. Heading; References. All headings used herein are used for
convenience only and shall not be used to construe or interpret this Note.
Except where otherwise indicated, all references herein to Sections refer to
Sections hereof.

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         IN WITNESS WHEREOF, the Company has caused this Note to be issued this
27th day of January, 2000.

                                               PINNACLE TOWERS III INC.


                                               By_______________________________
                                                 Steven R. Day, Vice President


                                               Name of Holder:__________________

                                               Address:_________________________
                                                       _________________________