Stu - Three more suggestions: - remove the paint along the inside edges of the box where the lids meet the box sides and the C shaped front/back panels, and remove the paint under the screw heads (I used a dremel bit to grind a nice circle under the head). - try increasing the PA Bias a bit, so that you are reading 30-40mV instead of 20mV at the test points TP3/4. Gary S suggested this. - replace the grey heatsink thermal pads with Thermalcote conductive heatsink grease. In my case, this stabilized the power output over time, as well as improved the output instability.
I also had done the PCBoard mod to ground top/bottom sides near the relay down in front, suggested by someone else. I was able to work a handful for the spring sprint - including Steve VE3SMA - as a result of these changes. Good luck Colin Haig VE3MSC At 07:19 PM 2011-05-10, Stu2 wrote: >Thanks guys! > >It's quite weird. When I say key up, I mean activate the XV432 PTT with >the rig (exciter) in CW mode without pressing the CW key. That is, no >RF goes into the transverter. Just the simple fact of keying the >transverter while it is connected to something other than a 50 Ohm load >seems to set up an oscillation. > >Several people have suggested a pad. The output of the XV432 is a low >pass pi circuit. Since I don't want to reduce the RX gain, it would seem >this either needs to be in the amp's TX chain or the XV432's TX chain. >(i.e. before the TR relay) > >After I wrote my first message, I installed an SWR meter between the >XV432 and amp so I could adjust the Henry for the best SWR. >Unfortunately, this didn't cure the problem. The XV432 still oscillated. >I have another amp I can try. I also have a TS2000 to try to help set >the amp up. > >Thanks again for the ideas. > >Stu2 >______________________________________________________________ >Elecraft mailing list >Home: http://mailman.qth.net/mailman/listinfo/elecraft >Help: http://mailman.qth.net/mmfaq.htm >Post: mailto:Elecraft@mailman.qth.net > >This list hosted by: http://www.qsl.net >Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
