I have one of these installed on a D=104 that has been retrofitted to an electret cartridge (never found a decent original element that survived!) I installed a K7DYY Mk II processor board to take advantage of the all phase filter and compressor. The noise gate feature is disabled. I noted on the Wireless Girl's webpage she suggests reducing the value of R-17 to limit the compression control range. I can easily do that. I also noticed the board's response curves offer a good peak at about 3-5 kHz, with a sharper roll-off than "stock" above 4.5 kHz. I've read some negative comments about this board on this forum, and I'm curious as to why this board is supposedly only usable with the K7DYY transmitter? The design seems reasonable??