If the promissory note is an installment or balloon note, this section will detail the amount of each payment or the final lump sum due, respectively. Use this unsecured promissory note (installment with balloon final payment) to make your loan official.Create and download a promissory note for free! The Illinois Unsecured Promissory Note Template is a legal document that is available in . How Do You Fill Out an Illinois Note? A promissory note is a written, signed document containing a borrower's unconditional promise to pay a specific sum to a lender. A balloon payment is an inflated one-time amount owed, usually after interest-only payments have been remit over the life of the loan. Step 2 Secured or Unsecured?