Bob, The info you need is contained in FMR-1735A-1 dated June 1996
The Audio squelch board in the radio is replaced with HLN5342ESP01 >From Pin 9 on the front connector (the former busy light line) on the interconnect board, the signal feeds through JU1510 to pin 12 of J21 the audio board connector. JU1509 and 1511 are open, JU1512 is in. J21 pin 12 is the pin 2 input of U1103. JU1202 is out. IIRC busy light is not used on A7 heads with the remote squelch control option. It's possible that you have a missmatch between the head and audio squelch board. Milt N3LTQ ----- Original Message ----- From: "Bob M." <[EMAIL PROTECTED]> To: <[email protected]> Sent: Monday, February 04, 2008 6:26 AM Subject: Re: [Repeater-Builder] Re: Low-band MaraTrac Squelch Pots > Thanks to the people who posted the link. I had seen > that page earlier but didn't follow the signal off the > board. > > The pot in the control head seems to have its arm and > one end connected to ground. The other end goes > through some resistors before leaving the control > head. I can see the effect of turning the pot down at > pin 9 of the control cable; it varies from about 3-5 > kOhms. I thought it was just a DC signal or just a > varying resistance to ground. > > The schematic posted doesn't show the wiring from the > audio board out to the pot on the control head. I'm > guessing that the signal coming into the squelch pot > on the audio board is detected audio, since it then > feeds the internal squelch pot which sets the gain and > threshold of the squelch circuit. > > I'll have to rethink and evaluate this new > information. > > Bob M. > ====== > --- sgreact47 <[EMAIL PROTECTED]> wrote: > >> Bob, >> >> Look here for the modified audio board. >> >> http://www.batlabs.com/images/marsqsch.jpg >> >> The squelch control circuit is there, uses the >> Micor, MSF, high >> speed squelch. >> >> "Bob M." <[EMAIL PROTECTED]> wrote: >> > >> > I'm working on a 42-50 MHz MaraTrac with the A7 >> > advanced head that has a squelch pot on it. The >> > squelch is open all the time, and neither the >> control >> > head pot or the pot inside the radio will close >> the >> > squelch. > > > > ____________________________________________________________________________________ > Never miss a thing. Make Yahoo your home page. > http://www.yahoo.com/r/hs > > > > > > Yahoo! Groups Links > > >
