50055/12MF01!.DOC              6
                                                   Exhibit 4.2(d)
                                                                 
                                
                                
                         LOAN AGREEMENT
                                
     THIS LOAN AGREEMENT, made and entered into this 24th day of
June, 1996, by and between ABERDEEN DEVELOPMENT CORPORATION, a
South Dakota Corporation, with offices at 514.5 South Main Street,
PO Box 1179, Aberdeen, South Dakota  57402-1179, hereinafter
called "LENDER", and APA OPTICS, INC., a Minnesota for profit
corporation with principal offices at 2950 N.E. 84th Lane,
Blaine, Minnesota  55449, hereinafter called "BORROWER",

                      W I T N E S S E T H:
                                
     THAT IN CONSIDERATION OF THE COVENANTS AND CONDITIONS
HEREINAFTER CONTAINED IT IS HEREBY MUTUALLY AGREED AS FOLLOWS:

     1.   That LENDER agrees to loan to BORROWER and BORROWER
agrees to borrow funds from the Aberdeen Development Corporation
pursuant to the terms and conditions of this Loan Agreement, the
sum of $300,000.00 which shall be evidenced by APA Optics, Inc.
signing a Promissory Note in favor of Aberdeen Development
Corporation in the sum of $300,000.00 to be paid over twenty (20)
years with interest at the rate of 3% per annum.  Balloon payment
after 5th year.  Interest shall be calculated from January 1st to
December 31st each year and predicated on 365 days.  Payments
shall be applied first to interest then to principal as payments
are made and required hereunder.

     Payments in the amount of $1,663.79 to begin on or before
July 24, 1996 and a like amount thereafter due and payable on the
24th day of each and every month.  Balance of $240,926.52 due at
end of 5th year or after 60th payment.

     Payments shall be made by BORROWER to LENDER at LENDER'S
address hereinafter set forth.

     Borrower may prepay the obligation represented by this
agreement, both principal and interest, at any time without any
penalty whatsoever.

     Borrower will establish a budget for construction of
facility and acquisition of equipment, etc. for that facility for
an amount of $3,200,000.00.  Borrower further covenants and
agrees that for the first 24 months following execution of this
Agreement it will provide Lender with an accounting reflecting
expenditures made under budget from the proceeds provided by
Lender to Borrower under this Agreement.

     2.   Whenever and wherever time appears herein time shall be
considered of the essence.

     3.   For purpose of this agreement all notice or notices
given shall be sent as follows:

     To LENDER:

     Aberdeen Development Corporation
     514.5 South Main Street
     PO Box 1179
     Aberdeen, SD  57402-1179

     To BORROWER:

     APA Optics, Inc.
     2950 N.E. 84th Lane
     Blaine, MN  55449

     4.   The Borrower agrees with Lender and represents as
follows:

     A.   Borrower shall carry key man life insurance on Dr. Anil
          Jain, as principal officer, in an amount of
          $2,000,000.00 and shall give proof of the carrying of
          such coverage to Lender and, if requested, shall
          provide a duplicate or specimen policy and, similarly,
          Borrower shall give proof on an annual basis of the
          payment of premiums on said life insurance policy so
          long as this agreement and the debt represented thereby
          is outstanding.
          
     B.   Borrower represents its current senior management are:
          Jain, Khan, Olsen and Becker and that these individuals
          are management and any change in management for
          whatever reason shall result in Borrower being required
          to give notice to the that effect to Lender.
          
     C.   Borrower covenants that as of the date of this
          agreement the company is free from any union
          representation and that as of the date of this
          agreement there is not active organizational campaign
          going on seeking representation for Borrower's
          employees.
          
     D.   Borrower covenants that as of the date of this
          agreement the equipment both at its Blaine operation
          and at Aberdeen, or to be acquired for Aberdeen, will
          be provided by exhibit to this agreement and that
          current equipment as represented has not changed as to
          ownership or placement or location nor is any exhibited
          equipment subject to any lease with Borrower being the
          lessee thereof except for leases of equipment with an
          aggregate book value not in excess of $100,000.00.
          Borrower covenants further that if any or all of the
          equipment from either the Blaine, Minnesota plant or
          Aberdeen, South Dakota plant, at any time during the
          term of this agreement while said loan is in place and
          remains unpaid, is removed without the permission or
          consent of Lender that this will constitute a condition
          of default and Borrower may declare the full sum due
          and owing payable immediately.  Provided, however, that
          Borrower may remove for resale or trade-in purposes
          equipment having for that purpose a value of $15,000.00
          per transaction with the further understanding that in
          no event will Borrower remove property for resale or
          trade or for surplus or obsolescence having annually a
          total value of $75,000.00 while this Agreement is still
          in full force and effect.
          
     E.   Borrower further covenants that as of the date of this
          agreement all tax obligations and liabilities on
          properties whether at Blaine, Minnesota or to be used
          in the Aberdeen, South Dakota project are current and
          paid and no deficiency or delinquency exists and that
          Borrower covenants and agrees that it will continue to
          keep all tax payments and liabilities, whether real
          property or personal property, paid and current so that
          the same are not in default and in the event of default
          acknowledges that Lender may make those payments and
          add any of those payments to the obligation under this
          agreement, shall add interest thereto and it shall
          become a continuing and ongoing obligation of Borrower
          until paid.
          
     F.   Borrower covenants and agrees that it will maintain
          life insurance as previously in this agreement
          mentioned and will similarly carry general liability in
          the amounts as set forth in Certificate of Insurance
          exhibit attached to this agreement and as set forth as
          follows:
          
          General aggregate                 $1,000,000
          Products-comp aggregate            $1,000,000
          Personal and ADY injury            $1,000,000
          Each occurrence                   $1,000,000
          Fire damage (any one fire)         $100,000
          Medical expenses (any one person) $5,000
          Automobile liability - combined single limit
$1,000,000
          Excess liability (each occurrence).     $3,000,000

          
          Borrower covenants and agrees that it will furnish
          proof of coverage and proof of payment so long as this
          agreement shall remain in full force and effect.
          
     G.   Borrower covenants and agrees that it has a reporting
          obligation to Lender so long as the obligation under
          this agreement remains in effect to report as to the
          business condition and in addition agrees that it will
          provide to the observer, who will be an agreed party to
          represent the interest of Lender, all financial data
          and information reasonably sought by such observer and
          further covenants and agrees that information shall be
          prepared in accordance with accepted accounting
          standards consistent with FASBE regulations and shall
          no less frequently than quarterly provide a statement
          of operations of the business of APA OPTICS, INC. at
          both its Blaine, Minnesota and Aberdeen, South Dakota
          operations.
          
     H.   Borrower covenants that so long as this agreement is
          outstanding or any debt represented thereby is still
          due and owing that it will indemnify and hold harmless
          Lender from any cause of action, claim or proceeding
          brought by any person, partnership, corporation or any
          entity whatsoever against Lender for any claim or
          demand arising out of the operation of APA OPTICS,
          INC., Blaine, Minnesota or Aberdeen, South Dakota, and
          further agrees to provide defense costs, including
          reasonable attorney's fees to Lender, by reason of it
          being involved in such litigation.
          
     I.   In addition to this agreement Borrower covenants and
          agrees to execute appropriate security agreements
          covering only its equipment in the Blaine, Minnesota
          plant and its personal property in the ultimate
          Aberdeen, South Dakota facility, provided, however,
          that when Borrower's obligation to Lender for this
          Agreement, and for any and all other financial
          agreements cumulatively, has an unpaid balance of [not
          more than] $250,000.00 plus the remaining balance on
          the $250,000.00 note from the Borrower to the Lender
          dated as of the date hereof, then Lender covenants and
          agrees to satisfy and cancel the security agreements
          then in place and outstanding.
          
     J.   Borrower covenants and agrees that it will pay all
          costs, expenses and fees in connection with this and
          other loan agreements as relates to the Aberdeen, South
          Dakota project, which includes but is not necessary
          limited to recording fees, filing fees or other costs
          incurred by any public entity by reason of
          acknowledgment of any documentation or records
          supporting this loan environment.
          
     K.   Borrower covenants and agrees that in the event of
          default of any of the warranties, representatives,
          conditions or covenants of Borrower that Lender at its
          sole option and discretion shall have the right to
          determine whether or not such default shall constitute
          significant default for the purpose of declaring the
          full sum due under this agreement immediately due and
          payable or whether to allow or permit Borrower to
          correct such default.  Such action on the part of
          Borrower in any case shall be no later than 30 days
          from the date of the occurrence of such default.
          
     5.   This agreement shall be governed by the laws of the
state of South Dakota regardless of the residence, personal or
corporate, of any of the parties to this agreement.

     6.   This agreement may be executed in original and in one
or more counterparts but shall constitute one and in the same
agreement.



     IN WITNESS WHEREOF, the parties hereto have caused this
agreement to be executed the day and year first above written.

                              ABERDEEN DEVELOPMENT CORPORATION
                              
                                    
ATTEST                        By:   /s/ Rodney Fouberg
:
                                    Its President
/s/ James C. Barringer              
Its Executive Vice                  LENDER
President
                                    
WITNESS:                            
                                    
/s/ Cheryl A. Olson                 
                              APA OPTICS, INC.    
                                    
ATTEST                        By:   /s/ Anil K. Jain
:
                                    Dr. Anil Jain
/s/ Kenneth A. Olsen                Its President
Its Vice President                  
                                    BORROWER
WITNESS:                            
                                    
/S/ Randal J. Becker                





Prepared by:
MALONEY & MALONEY
PO Box 755
Aberdeen, SD  57402-0755
605/229-2752