At 5/31/2008 13:55, you wrote: >Hello Ron, > >The audio emphasis for FM is a different issue. When I put the >discriminator output from the Mastr II receiver on a analyzer you can >clearly see a spike way out at 455khz which I believe is the IF >frequency in the receiver. > >This controller has a auto-squelch feature (it does not use a COS/RUS >line at all) and it listens for the presence of high-frequency noise >coming off of the receiver to control the squelch. When a nice, full >quieting FM signal shows up the high frequency noise goes away and the >controller will detect this and kick on the transmitter. > >This detection circuit is behaving poorly on the Mastr II because this >strong 455khz component is throwing it off and making it shut down the >squelch because it thinks there's a lot of high-frequency noise even >when the signal is actually full quieting.
Perhaps this was covered earlier in the thread, but are you getting your discriminator output from VOL/SQ HI? I've never seen any significant 455 kHz at this point, yet it still contains all the high frequency unde-emphasized noise your outboard squelch circuit needs. Bob NO6B
