Ah ha!! I have finally found the problem. Skipp and Kevin both suggested that I look long and hard at the channel element, and just to be sure, I ordered a new one today from ICM. But that was not the problem ;o) That's okay, as I really would prefer a new ICM element anyway.
Went down to the shop tonite to conduct some tests on the channel element that Skipp suggested to me, injecting a high level PL tone into the PL tone input of the exciter. I figured I would first disconnect the TS-64 tone board, and monitor that point with a scope to see exactly what was hitting the "splatter filter" in the exciter's audio chain. As soon as I plugged the radio in, I knew we had found the problem as the deviation increased several fold. For some reason, the TS-64 was pulling down the audio line. Disconnect it and now the modulation is clean as a whistle (grin) at 1 KHz to over 6 KHz deviation. No distortion is evident on the service monitor scope at all. In thinking back over all the symptoms, the fact that I was seeing increasing deviation with increasing audio frequency feeding an audio generator directly into the exciter should have been the tip off. All of the pre-emphasis I believe is done external to the exciter, yet I was seeing obvious pre-emphasis, and could not make rated deviation at 1 KHz audio frequency. I've got several brand new TS-64's on the shelf, and will install a new one tomorrow. To put it mildly, I am really stoked that the problem is finally solved. Thanks very much to those who tried to help me with this. Ah, life is good! 73, Army - AE5P --- In [email protected], "Army Curtis - AE5P" <[EMAIL PROTECTED]> wrote: > Good point. The channel element was simply recrystalled by the folks > we bought the MSR-2000 from, and I also am looking hard at it. I did > try another channel element I had on hand that was done by Channel > Element Headquarters, and it did the same thing. I believe I will > send one of them off to ICM and have them do a new one that I KNOW > will be right, and see if that makes a difference. > > We bought 4 of these repeaters, and I'm about at my wits end with > them. I believe my next step while I'm waiting on the new channel > element to come from ICM will be to convert one of the other 3, and > see what it does. And I believe I may give the Squelch Gate card > interface a try, at least for the audio interface. Can't hurt ;o) > > Thanks for the ideas. > > Army - AE5P > > --- In [email protected], Kevin Custer <[EMAIL PROTECTED]> > wrote: > > Army Curtis - AE5P wrote: > > > > >No. The output of the controller goes to the Squelch-Gate card, > and > > >through the several stages of audio amplification there before > going > > >on to the exciter. Since that was the way Motorola designed it, > it > > >seemed like the best way to keep it. > > > > > > > Who did the channel element? If you re-crystaled it yourself, it > likely > > isn't working correctly. Try another (factory) channel element to > see > > if the problem goes away. If it does, consider having ICM or > Bomar redo > > your element. > > > > Kevin Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
