Silent Key Estate Sale: 1. 200 Hz 16 pole plug-in crystal filter for 75S-3B/C $300 2. 500 Hz mechanical plug in filter for 75S-3B/C $250 3. 2.1 kHz plug-in mechanical filter for 75S-3B/C or later KWM-2/2A $100 4. 2.1 kHz plug-in mechanical filter, I think for 75A4, P/N 455-J-21 5. 2 F500Z-11 3,2 kHz LSB $50 each or $90 for both. 73, Jerry W7BUN