J.J. deposited $1680 at the beginning of every 6 months for 8 years into a fund paying 5.5% compounded semi-annually. Seven years after the first deposit, he converted the balance into an annuity paying him equal monthly payments for 20 years. If the payments are made at the end of each month and interest on the annuity is 6% compounded monthly, what is the size of the monthly payments?