You're welcome. The spurs I was referring to weren't from the PA either. They were generated in the exciter. The PA just appeared to amplify them.
Moving the exciter output from the PA and into the service monitor, showed the spurs. After installing the inductor where the ptt line enters the exciter pcb, caused the spur to be lost in the noise floor. Then after moving the exciter output back to the PA, the spurs appeared clearly above the noise floor. Installing the inductors on the PA reduced them back into the noise floor. That is probably why GE put the inductors on their problematic PA version's voltage Supply. Again, the spurs were actually being generated in the exciter, by the icom's osc, from noise on the ptt line feeding it. The sources of that noise could be many -- even external to the MII. -Steve ----- Original Message ----- From: [EMAIL PROTECTED] To: [email protected] Sent: Friday, December 14, 2007 7:57 AM Subject: Re: [Repeater-Builder] Re: MastrII Mobil repeater spur At 12/13/2007 09:48, you wrote: >Randy, > >I've experienced problems similar to what you describe on several MII and >found it to be harmonic noise on the ptt (osc 10v) line. Installing >a >10 uh inductor where the line enters the exciter pcb did wonders for >mine. You may also want to install a pair of inductors on the 12v lines in >the PA (at the feed through caps). The original GE design has this on a >number of their PAs. > >While, once I did have a spur that required me to move the entire mobile >radio away from another mobile cased unit, I've never had a desense >problem internally between the tx and rx in a mobile. NO6B may want to >revisit his problem MII and look at the ptt line. He may be pleasantly >surprised. I'll have to try that next time I have the radio in front of me; thanks Steve. The spurs I'm seeing are not being manufactured in the PA, as they're present on the exciter output. I tried capacitive bypassing on the OSC 10V line, but perhaps that wasn't enough. Bob NO6B Yahoo! Groups Links
