[ICOM] 718 Speech Compressor

[Rick Robinson]

I looked at the IC-78 service manual and  I found a reference to the 
compressor circuit.  It should be the same as in the 718. Audio from the 
mic goes to the mic amplifier circuit, IC2201. This IC consists of a mic 
amp, mic gain controller,  speech compressor, and vox circuit.   In  AM 
mode the ALC circuit limits the output of IC2201. The maximum modulation 
level is set by R2385. I looked at IC 2201 on the schematic and it looks 
to me like there is some circuitry associated with the compressor input 
and output. Someone with more circuit knowledge than me will need to 
take a closer look. Maybe this will get a "fix" so to speak started. I 
am thinking about getting a 718 as I foolishly sold mine a couple of 
years ago. I split the tx and rx sections and made a set of Icom "twins" 
using my R75 for a receiver. With the remote and mute lines it made a 
really neat setup. Anyway I hope this help. 73, Rick, W8ZT.