Hi to all. I Want to Buy a 6Khz filter for my Collins 51S-1, in good work order. Is F 500 Y 60 7148, P/N 526 9378 00 Does anyone have one for sell, or know where to buy it?. Of course I would pay too all USPS cost to my QTH in Europe. very 73's Bruno Ortega-EA7FEB