<PAGE>

                                                                   Exhibit 4.1


SBIC License No. 05/05-5134                                 Loan No. 04647751-06
                 ----------                                          -----------

                                      DEBENTURE

$3,000,000                                       Date of Issuance  JUNE 25, 1997
 ---------                                                         -------------

         CAPITAL DIMENSIONS VENTURE FUND, INC.                  (the "Company")
----------------------------------------------------------------
    (Name of Licensee

    TWO APPLETREE SQUARE, SUITE 335, MINNEAPOLIS, MN  55425-1637
--------------------------------------------------------------------------------
    (Street)                         (City)    (State)  (Zip)

For value received, the Company hereby promises to pay to the order of Chase
Manhattan Bank, as Trustee (the "Trustee") under that certain Amended and
Restated Trust Agreement dated as of December 1, 1996, as same may be amended
from time to time, by and among the Trustee, the U.S. Small Business
Administration ("SBA") and SBIC Funding Corporation, and as the Holder hereof
the principal sum of THREE MILLION DOLLARS ($3,000,000) (the "Original Principal
Amount") on June 2, 1007 (the "Maturity Date") at such location as SBA, as
guarantor of this debenture, may direct and to pay interest semiannually on June
1st and December 1st (the "Payment Dates") of each year, as herein provided, at
the rate of 7.07% per annum (the "Stated Interest Rate"), and to pay a 1% per
annum fee to SBA on the above dates, on the basis of a year of 365 days, for the
actual number of days (including the first day but excluding the last day)
elapsed, on said principal sum from the date of the issuance hereof until
payment of such principal sum has been made or duly provided for.  The Company
shall deposit all payments with respect to this debenture not later than 12:00
noon (Washington, D.C. time) on the applicable Payment Date or the next business
day if the Payment Date is not a business day, all as directed by SBA.

This debenture is issued by the Company and guaranteed by SBA, pursuant and
subject to Section 303 of the Small Business Investment Act of 1958, as amended
(the "Act") (15 U.S.C. Section 683).  This debenture is subject to all of the
regulations promulgated under the Act, as amended from time to time, provided,
however, that 13 C.F.R. Sections 107.1810 and 107.1830 through 107.1850 as in
effect on the date of this debenture are incorporated herein as if fully set
forth.

The Company may elect to prepay this debenture, as a whole and not in part, on
any Payment Date, in the manner and at the price as next described.  The
prepayment price (the "Prepayment Price") shall be an amount equal to the
outstanding principal balance of this debenture, plus interest accrued and
unpaid thereon to the Payment Date selected for prepayment, plus a prepayment
premium (the "Prepayment Premium").  The Prepayment Premium amount is calculated
as a declining percentage (the "Applicable Percentage") multiplied by the
Original Principal Amount of this debenture in accordance with the following
table:


                                          1

<PAGE>

    Consecutive Payment Dates                    Applicable Percentage

         1st    or    2nd                                  5%

         3rd    or    4th                                  4%

         5th    or    6th                                  3%

         7th    or    8th                                  2%

         9th    or    (10th--If Not also Maturity Date)    1%

No Prepayment Premium is required to repay this debenture on its Maturity Date.
No Prepayment Premium is required when the prepayment occurs on a Payment Date
that is on or after the 11th consecutive Payment Date of this debenture, if this
debenture has a 20 consecutive Payment Date term.

The amount of the Prepayment Price shall be sent to SBA or such agent as SBA
shall direct, by wire payment in immediately available funds, not less than
three business days prior to the regular payment date.  Until the Company is
notified otherwise in writing by SBA, any Prepayment Price shall be paid to the
account maintained by the Trustee, entitled the SBA Prepayment Subaccount and
shall include an identification of the Company by name and SBA-assigned license
number, the loan number appearing on the face hereof, and such other information
as SBA or its agent may specify.

This debenture shall be deemed issued in the District of Columbia as of the day,
month, and year first stated above.  The terms and conditions of this debenture
shall be construed in accordance with, and its validity and enforcement governed
by, federal law.

The warranties, representations, or certifications made to SBA on the SBA Form
1022 or the Company's application letter for an SBA commitment related to this
debenture are incorporated herein as if fully set forth.

Should any provision of this debenture or any of the documents incorporated by
reference herein be declared illegal or unenforceable by a court of competent
jurisdiction, the remaining provisions shall remain in full force and effect and
this debenture shall be construed as if said provisions were not contained
herein.

All notices to Company which are required or may be given under this debenture
shall be sufficient in all respects if sent to the above-noted address of the
Company.  For the purposes of this debenture, the Company may change this
address only upon written approval of SBA.

COMPANY ORGANIZED AS CORPORATION

IN WITNESS WHEREOF, the Company has caused this debenture to be signed by its
duly authorized officer and its corporate seal to be hereunto affixed and
attested by its Secretary or Assistant Secretary as of the date of issuance
stated above.

<PAGE>

CORPORATE SEAL
    None

                             CAPITAL DIMENSIONS VENTURE FUND, INC.



                             By:  /s/ Thomas F. Hunt, Jr.
                                  ---------------------------------------
                                      Thomas F. Hunt, Jr., President


ATTEST:


  /s/ Brenda L. Leonard
-----------------------------------------
Brenda L. Leonard, Secretary