<PAGE>
 
                                                                   EXHIBIT 10.84

                            SAHARA LAS VEGAS CORP.

                     TRANCHE A NOTE DUE DECEMBER 15, 1999


                                                                   July 31, 1997
$15,000,000                                              Los Angeles, California

          FOR VALUE RECEIVED, the undersigned, SAHARA LAS VEGAS CORP. (herein
called the "Company"), a corporation organized and existing under the laws of
the State of Nevada, hereby promises to pay to OKGBD & Co., as nominee for
SUNAMERICA, INC. or registered assigns ("Holder"), the principal sum of FIFTEEN
MILLION DOLLARS ($15,000,000) on December 15, 1999 with interest (computed on
the basis of actual days elapsed and a 360-day year of twelve 30-day months) on
the unpaid balance thereof at 12% per annum from the date hereof, payable semi-
annually on June 20 and December 20, commencing on December 20, 1997, and the
stated maturity of this Note, and, to the extent permitted by law, upon the
occurrence of and continuation of an Event of Default (as defined in the Note
Purchase Agreement), interest, payable, on demand, at a rate per annum from time
to time equal to 2% per annum above the interest rate specified above.  In
addition to interest as set forth herein, if any payment of principal and/or
interest or any other amount payable hereunder or under the other Basic
Documents (as defined in the Note Purchase Agreement) is not paid when due,
Company shall pay to each Holder, on demand, a late charge of five cents ($0.05)
for each dollar so overdue in order to compensate such Holder for its loss of
the timely use of the money and frustration of such Holder in the meeting of its
financial commitments.  Nothing contained herein shall constitute an extension
of any due date for, or a waiver of any obligation to pay, any amounts payable
hereunder or under the other Basic Documents.

          Payments of principal of, interest on and late charges with respect to
this Note are to be made in lawful money of the United States of America as
provided in the Securities Purchase Agreement referred to below.

          This Note is one of the Tranche A Notes (herein called the "Notes")
issued pursuant to the Amended and Restated Note Purchase Agreement, dated as of
July 29, 1997 (as from time to time amended, modified or otherwise supplemented,
the "Note Purchase Agreement"), among the Company, Santa Fe Gaming Corporation
(formerly named Sahara Gaming Corporation), SunAmerica Life Insurance Company,
as Collateral Agent, and the Holders party thereto and is entitled to the
benefits thereof.  Each holder of this Note will be deemed, by its acceptance
hereof, to have made the representation set forth in Section 2.9 of the Note
Purchase Agreement.

          This Note, together with the other notes issued pursuant to the Note
Purchase Agreement, are secured by the Company Deed of Trust, the Company
Security Agreement and certain other Basic Documents (as such terms are defined
in the Note Purchase Agreement) and is guaranteed by the SGC Guaranty, the
Sahara Resorts Guaranty and the other Guaranties (as such terms are defined in
the Note Purchase Agreement).

                                       1
<PAGE>
 
          This Note is a registered Note and, as provided in the Note Purchase
Agreement, upon surrender of this Note for registration of transfer, duly
endorsed, or accompanied by a written instrument of transfer duly executed, by
the registered holder hereof or such holder's attorney duly authorized in
writing, a new Note for a like principal amount will be issued to, and
registered in the name of, the transferee.  Prior to due presentment for
registration of transfer, the Company may treat the person in whose name this
Note is registered as the owner hereof for the purpose of receiving payment and
for all other purposes, and the Company will not be affected by any notice to
the contrary.

          The Company will make required prepayments of principal on the dates
and in the amounts specified in the Note Purchase Agreement.  This Note is also
subject to optional prepayment, in whole or from time to time in part, at the
times and on the terms specified in the Note Purchase Agreement.

          If an Event of Default, as defined in the Note Purchase Agreement,
occurs and is continuing, the principal of this Note may be declared or
otherwise become due and payable in the manner, at the price and with the effect
provided in the Note Purchase Agreement.

                                       2
<PAGE>
 
          This Agreement shall be construed and enforced in accordance with, and
the rights of the parties shall be governed by, the law of the State of Nevada
excluding choice-of-law principles of the law of such State that would require
the application of the laws of a jurisdiction other than such State.


                                    SAHARA LAS VEGAS CORP.


                                    By  /s/ Thomas K. Land
                                      ----------------------------------------
                                         Thomas K. Land

                                    Title:  Treasurer and Assistant Secretary


                                    By  /s/ Paul W. Lowden
                                      ----------------------------------------
                                         Paul W. Lowden

                                    Title:  President


                                      S-1
<PAGE>
 
                      OPTION OF HOLDER TO ELECT REPURCHASE



          If you want to elect to have this Note purchased by Company pursuant
to Section 2.5C(v) of the Note Purchase Agreement, check the box:  [_]
   ---------------                                                  


          If you want to elect to have only part of this Note purchased by
Company pursuant to Section 2.5C(v) of the Note Purchase Agreement, state the
                    ---------------                                          
amount (which must be $1,000 or an integral multiple of $1,000):

                                       $____________________


Date: ___________________              Signature:_____________________________
                                                  (Sign exactly as your name
                                                   appears on the other side of
                                                   this Note)

Signature Guarantee: