{Collins} S-Line PTO Frequency Stability Tip

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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