[R-390] Fw: R-390/URR PTO calibration

Tue Nov 26 23:59:35 EST 2019

I sent an email to Tom but want to also send it to the list:

Bob
kb1okl

Bob,

I think you are talking about two different things.

The most common problem is the endpoint adjustment.  You want your PTO to have an output range of exactly 1000 kcs in 10 turns.  You can detect this with your crystal calibrator (provided it is accurate).

Typically as the PTO ages it takes a tad more than ten turns to get the full 1000 kcs of output range.  It sounds like yours is doing about 997 kcs in ten turns.

The way to adjust this is to turn the endpoint adjustment screw at the front of the PTO and check it again.

If this is in fact your problem it is separate from the 7000+ or 2.000 stuff you mentioned.

Look up endpoint adjustment in the literature.

73 N5OFF Tom

________________________________
From: Bob Young <bobyoung53 at hotmail.com>
Sent: Tuesday, November 26, 2019 11:57 PM
To: Tom M. <courir26 at yahoo.com>
Subject: Re: [R-390] R-390/URR PTO calibration

Thanks Tom, I got that from this:

" Before you replace the PTO check the setting of the 10 turn stop. In its fully counterclockwise position the dial should read between -963 and -972. If it is outside this range adjust the ten turn stop until it does. If the error is minimal the best way to do this is to loosen the small bevel gear on the counter and reset it. After doing this be sure to check the mechanical synchronization. The check point is 2.000 MHz for the R-390 and 7.000+ for the R-390A."

http://r-390.com/pto.htm

I did use 7.000+. I have two PTO's and neither of them seem to adjust very much if at all using S701 to adjust the endpoint. I took the cover off one of them and the round inductor doesn't seem to be attached to the round metal cover and the whole thing twists when you turn the shaft, I assume this is not the way it is supposed to work but can't see how it is supposed to be attached, glued maybe? I have adjusted R-390A's before and had no problems setting the end point with them. I assume it should work as in an R-390A. Could I be doing something wrong? Maybe I used too much pressure turning it in and broke whatever bond was there? I have looked up the procedure in two different places, this is the one I'm using:

http://amfone.net/Amforum/index.php?topic=25191.0;wap2

Thanks,

Bob kb1okl
Collins 390 PTO calibration for newbies - AM Fone<http://amfone.net/Amforum/index.php?topic=25191.0;wap2>
Collins 390 PTO calibration for newbies (1/2) > >> iw5ci: I would like to align the pto linearity in my collins 390 non A. From start to end of any mhz segment i have 3 - 4 khz of disalignment on the mechanical digital readout.
amfone.net

pto - r-390.com<http://r-390.com/pto.htm>
THAT PESKY ENDPOINT. (Revised 6/6/99) When I do this I use a jig to make the procedure more accurate.. This jig is a simple mounting for
r-390.com

________________________________
From: Tom M. <courir26 at yahoo.com>
Sent: Tuesday, November 26, 2019 7:56 PM
To: r-390 at mailman.qth.net <r-390 at mailman.qth.net>; Bob Young <bobyoung53 at hotmail.com>
Subject: Re: [R-390] R-390/URR PTO calibration

Bob,