[R-390] re: Dangling PTO

[Al Parker]

Hi Rick,
    If the end-to-end span is more than 7 or 8 kc off, you probably won't
be able to adjust it externally to get within reasonable dial "zero"
adjustment.  They drift over the yrs, usually by now at least 7kc.  The
compensating coil slug can be moved externally, without doing more than
removing the panel, or less if you have u-joint fingers and some small
tools.  There's a hex cap over the coil slug adjustment, on the front end,
top, of the PTO.
    I have remedied a number of them, from R-388's, 51J-'s and 75A's,
after removing them from the chassis, which can be a little dicey, but not
hazardous to anything.  1 or 1-1/2 turns need to be removed from the
compensating coil.  Take a look on my website under the "Collins" links to
see some of it.
http://www.boatanchors.org
    There have been some articles written in past QST or CQ, etc., I have
some cc's, will scan for you if you'd like.  Don't worry about the
"WARNING" about breaking the seal, somebody's probably done it anyway, and
even if not, the desiccant is long past it's usefulness, and I haven't
been able to reclaim it ever.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.boatanchors.org
http://www.hammarlund.info

======================
Message: 6
Date: Sat, 19 Aug 2006 15:25:52 -0500
From: Rick Brashear <rickbras at airmail.net>
Subject: [R-390] Dangling PTO
To: R-390 at mailman.qth.net
Message-ID: <44E773D0.7050205 at airmail.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

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