[R-390] Dangling PTO

[Tom M.]

The R-388 is not very PTO friendly, but that said, the endpoint can be adjusted
from the outside.

What I do is to uncouple the PTO (don't move anything) and access and turn the
endpoint adjusting screw on the front of the unit until the endpoint error
improves.  You may want to overshoot a tad because the 388 PTO endpoint moves
rapidly (in boatanchor years anyway).

If you are out of adjustment range with the endpoint adjusting screw then
you'll need to open the PTO can and take one turn off the endpoint adjustment
coil, and then start the endpoint adjustment all over again.

Some purists don't like opening the PTO because you expose the inards to moist
air.  What you can do before reassembly is to bake the PTO in any oven at about
110 F for several hours to dry it (and the dessicant bag) out and then
reassemble.  

Bonne chance.

Tom

--- Rick Brashear <rickbras at airmail.net> wrote:

> I realize this is a R-390 list, but I am sure the PTO in my R-388 is 
> about the same if not identical.  I have it dangling inside the 388 and 
> I felt it better if I ask a question or two before I go further.  I need 
> to adjust the end calibration, I think that what it's called, as I am 
> unable to correct the dial with the "ZERO" adjustment on either end of 
> all bands.  The 388 manual is very limited on information, suggesting to 
> simply exchange the defective VFO for a properly functioning one.  I 
> understand there is an adjustment under the can to take care of this.  I 
> have yet to remove the can, so I' don't know.  It is a Collins PTO 
> #70E-15.  Any help or direction would be most appreciated.  Do I need to 
> remove the PTO completely from the circuit by taking the wires loose or 
> can the adjustment be performed as is?
> 
> Thanks,
> Rick
> 
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