Exhibit 10.28


 





PROMISSORY NOTE


 


 


	$350,000	As of December 10, 2018


 


 


Black Ridge Acquisition
Corp. (“Maker”) promises to pay to the order of Black Ridge Oil & Gas, Inc. or its successors or assigns (“Payee”)
the principal sum of Three Hundred Fifty Thousand Dollars and No Cents ($350,000) in lawful money of the United States of America,
on the terms and conditions described below.


 


1.              
Principal. The principal balance of this Note shall be repayable on the consummation of the Maker’s initial
merger, capital stock exchange, asset acquisition or other similar business combination with one or more businesses or entities
(a “Business Combination”). Payee understands that if a Business Combination is not consummated, this Note will not
be repaid and all amounts owed hereunder will be forgiven except to the extent that the Maker has funds available to it outside
of its trust account established in connection with its initial public offering.


 


2.              
Interest. No interest shall accrue on the unpaid principal balance of this Note.


 


3.              
Application of Payments. All payments shall be applied first to payment in full of any costs incurred in the collection
of any sum due under this Note, including (without limitation) reasonable attorneys’ fees, then to the payment in full of
any late charges and finally to the reduction of the unpaid principal balance of this Note.


 


4.              
Events of Default. The following shall constitute Events of Default:


 


(a)           
Failure to Make Required Payments. Failure by Maker to pay the principal of this Note within five (5) business days
following the date when due.


 


(b)           
Voluntary Bankruptcy, Etc. The commencement by Maker of a voluntary case under the Federal Bankruptcy Code, as now
constituted or hereafter amended, or any other applicable federal or state bankruptcy, insolvency, reorganization, rehabilitation
or other similar law, or the consent by it to the appointment of or taking possession by a receiver, liquidator, assignee, trustee,
custodian, sequestrator (or other similar official) of Maker or for any substantial part of its property, or the making by it of
any assignment for the benefit of creditors, or the failure of Maker generally to pay its debts as such debts become due, or the
taking of corporate action by Maker in furtherance of any of the foregoing.


 


(c)           
Involuntary Bankruptcy, Etc. The entry of a decree or order for relief by a court having jurisdiction in the premises
in respect of maker in an involuntary case under the Federal Bankruptcy Code, as now or hereafter constituted, or any other applicable
federal or state bankruptcy, insolvency or other similar law, or appointing a receiver, liquidator, assignee, custodian, trustee,
sequestrator (or similar official) of Maker or for any substantial part of its property, or ordering the winding-up or liquidation
of its affairs, and the continuance of any such decree or order unstayed and in effect for a period of 60 consecutive days.


 


5.              
Remedies.


 


(a)           
Upon the occurrence of an Event of Default specified in Section 4(a), Payee may, by written notice to Maker, declare this
Note to be due and payable, whereupon the principal amount of this Note, and all other amounts payable thereunder, shall become
immediately due and payable without presentment, demand, protest or other notice of any kind, all of which are hereby expressly
waived, anything contained herein or in the documents evidencing the same to the contrary notwithstanding.


 


(b)           
Upon the occurrence of an Event of Default specified in Sections 4(b) and 4(c), the unpaid principal balance of, and all
other sums payable with regard to, this Note shall automatically and immediately become due and payable, in all cases without any
action on the part of Payee.


 


 


 






    	 	1	 



     


    

 


6.              
Conversion. Upon consummation of a Business Combination, the Payee shall have the option, but not the obligation,
to convert the principal balance of this Note, in whole or in part at the option of the Payee, into units (“Units”)
of the Maker at a price of $10.00 per Unit, each Unit being identical to the “private units” (as defined in Maker’s
final prospectus dated October 4, 2017). As promptly after notice by Payee to Maker to convert the principal balance of this Note,
which must be made at least 24 hours prior to the consummation of the Business Combination, as reasonably practicable and after
Payee’s surrender of this Note, Maker shall have issued and delivered to Payee, without any charge to Payee, a certificate
or certificates (issued in the name(s) requested by Payee) for the number of Units of Maker issuable upon the conversion of this
Note.


 


7.              
Waivers. Maker and all endorsers and guarantors of, and sureties for, this Note waive presentment for payment, demand,
notice of dishonor, protest, and notice of protest with regard to the Note, all errors, defects and imperfections in any proceedings
instituted by Payee under the terms of this Note, and all benefits that might accrue to Maker by virtue of any present or future
laws exempting any property, real or personal, or any part of the proceeds arising from any sale of any such property, from attachment,
levy or sale under execution, or providing for any stay of execution, exemption from civil process, or extension of time for payment;
and Maker agrees that any real estate that may be levied upon pursuant to a judgment obtained by virtue hereof, on any writ of
execution issued hereon, may be sold upon any such writ in whole or in part in any order desired by Payee.


 


8.              
Unconditional Liability. Maker hereby waives all notices in connection with the delivery, acceptance, performance,
default, or enforcement of the payment of this Note, and agrees that its liability shall be unconditional, without regard to the
liability of any other party, and shall not be affected in any manner by any indulgence, extension of time, renewal, waiver or
modification granted or consented to by Payee, and consents to any and all extensions of time, renewals, waivers, or modifications
that may be granted by Payee with respect to the payment or other provisions of this Note, and agree that additional makers, endorsers,
guarantors, or sureties may become parties hereto without notice to them or affecting their liability hereunder.


 


9.              
Notices. Any notice called for hereunder shall be deemed properly given if (i) sent by certified mail, return receipt
requested, (ii) personally delivered, (iii) dispatched by any form of private or governmental express mail or delivery service
providing receipted delivery, (iv) sent by telefacsimile or (v) sent by e-mail, to the following addresses or to such other address
as either party may designate by notice in accordance with this Section:


 


If to Maker:


 


Black Ridge Acquisition Corp.


c/o Black Ridge Oil & Gas,
Inc.


110 North 5th Street, Suite 410


Minneapolis, MN 55403


 


If to Payee:


 


Black Ridge Oil & Gas, Inc.


110 North 5th Street, Suite 410


Minneapolis, MN 55403


 


Notice shall be deemed
given on the earlier of (i) actual receipt by the receiving party, (ii) the date shown on a telefacsimile transmission confirmation,
(iii) the date on which an e-mail transmission was received by the receiving party’s on-line access provider (iv) the date
reflected on a signed delivery receipt, or (vi) two (2) Business Days following tender of delivery or dispatch by express mail
or delivery service.


 


10.           
Construction. This Note shall be construed and enforced in accordance with the domestic, internal law, but not the
law of conflict of laws, of the State of New York.


 


11.           
Severability. Any provision contained in this Note which is prohibited or unenforceable in any jurisdiction shall,
as to such jurisdiction, be ineffective to the extent of such prohibition or unenforceability without invalidating the remaining
provisions hereof, and any such prohibition or unenforceability in any jurisdiction shall not invalidate or render unenforceable
such provision in any other jurisdiction.


 


IN WITNESS WHEREOF,
Maker, intending to be legally bound hereby, has caused this Note to be duly executed the day and year first above written.


 


	 	BLACK RIDGE ACQUISITION CORP.
	 	 
	 	 
	 	 
	 	By: /s/ James A. Moe
	 	Name:  James A. Moe
	 	Title: CFO


 


 


 






    	 	2