[R-390] R390A VFO backlash problem,

[Roger Ruszkowski]

Fellows,
I was asked this question and I do not know how to cure the back lash problem in these VFOs. May we have some help please?

Roger, You are going about the end point adjustment the right way. It takes time
and is boring. Tweak it a big bit to get closer faster. You may find starting from the other end helps you get the adjustment done. 

Hi Roger,
I hope you can shed some light on this PTO problem. I'm asking you because 
you seem to have had more experience than anyone else on the 390 list.
I have a Collins type PTO manufactured by Progressitron Corp. for Capehart. 
The PTO seems to have some backlash. If I set it for zero beat, it will jump 
back about 300Hz when I let go of the knob or shaft (with PTO removed). I 
have cleaned and lubricated the leadscrew and put a drop of oil in the front 
bearing, but it still does this. Any suggestions??
I have the PTO on the bench, coupled to a counter. The freq. was off quite a 
bit (~2kHz) after 10 turns. I have adjusted the endpoint slug and now have 
it within 700Hz. I have a pointer knob on the shaft, and have been setting 
the PTO at 3455.0 and marking the front plate, then after exactly 10 turns 
(2455.?) I see where I am relative to the starting mark and make another 
tweek of the slug. Back to 3455.0, another mark and do it all over again. Is 
there an easier way to make this adjustment?? I'd like to get it closer, but 
all this back and forth is driving me to drink!!
Looking forward to your comments and suggestions.
Roger Gates, W7KVT 

Thank you Fellows, 
Merry Christmas to all

Roger Ruszkowski  AI4NI