Re: {Collins} S-Line PTO Frequency Stability Tip



 Hi Dave
Thanks for the tip.
I tighteded everything around the PTO and watching
the VFO Out put with my Freq Counter.
That Did not solve the Problem.
                 Stan K6RMR

Maybe others have discovered this or it has been discussed, but I will pass
it along for anyone fighting PTO stability problems.



I recently had trouble with my 75S-3B PTO.  For months I noticed an
occasional momentary large frequency jump, then a return to the correct
frequency.  The warm up drift seemed much worse than I remembered.
Stability seemed to be deteriorating. Finally, the PTO either quit working
or went way off frequency.



While poking around inside the radio, I moved the PTO case back and forth,
flexing the unit.  The frequency changed noticeably when doing this.
Remembering the common recommendation to re-tighten screws on the band
switch cans to improve stability,  I thought I would try loosening and
re-tightening the two screws holding the PTO to the case.  And. Voila, the
problems went away!  A two minute job.



Now the warm up frequency drift is 200 Hz or less. It is quite stable after about 20-25 minutes and drifts very little after that. So, as a precaution,
I did this on all my S-Line gear.



So, before you tear into an unstable PTO to rebuild it, try this trick.



Dave Jennings WJ6W



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