[R-390] setting the PTO endpoints (long)

[David Wise]

My cut-down diddle stick is 3-1/4".

"Mechanic's creeper"... Need to warm up brain before
engaging mouth.  Turn the set over, duh.  But it's
still hard to see, and if your eyes can't handle
the mirror and close quarters, then you have little
choice but to remove the PTO.  (I wouldn't
drill an adjustment port in the front panel.)

My set has a Collins PTO.  I bought a Cosmos
spare a while back, and looking at it now, I
can see that it would be harder to do in situ.
(Mine needs repair first; the slug must have
frozen, because the slot is completely chewed
away.)

My Cosmos has the odd linearity screws.
I didn't put a magnifier on them, but
they look like Robertson (square) head.
I'll put it under a microscope and report back.

Dave Wise

-----Original Message-----
From: David Wise
Sent: Tuesday, March 10, 2009 3:18 PM
To: R-390 at mailman.qth.net
Subject: RE: [R-390] setting the PTO endpoints (long)

Thanks, Ed!

So you can even do Cosmos linearity in the radio, though it's
hard.  How about a frame to suspend it a foot or so off the
floor, and you go in on a mechanic's creeper?  Of course the
consequences are dire if the frame isn't solid...

Were you able to use the same tool for linearity and endpoint?
I seem to remember that Cosmos used more than one screw-head type.

Dave Wise

-----Original Message-----
From: DJED1 at aol.com [mailto:DJED1 at aol.com]
Sent: Tuesday, March 10, 2009 2:27 PM
To: David Wise; R-390 at mailman.qth.net
Subject: Re: [R-390] setting the PTO endpoints (long)

Yep, adjustments can be done with the PTO in the radio.  As  noted, I removed
the PTO to take out the nut which covers the adjusting screw,  then used a
cut down jewelers screwdriver to do the adjustment.  I even  went one better and
did all 42 adjustments on a Cosmos with the PTO in the  radio.  In that case,
adjustment was unmanageable while pulling the PTO  out, as I was trying to
get resettability to 100 cycles or so.  It was a  case of doing it in the radio
or making a special test fixture.  But it was  an undertaking, using a small
mirror to see where the slot was on each adjusting  screw.  By the time I got
done, I swore I would do whatever it took to  build a test fixture next time.
Ed