On Sun, 7 Sep 2008, mecograph wrote:

Hi Scott,

It's a Capehart R-390A. I'm not sure who made the PTO....I don't have
anyone to help me lift it out of the case so I can look at it this
evening.

I hope to have a friend help me extract it from the cabinet in the
next few days...I'll try to figure out which PTO it is.


I don't know how much of it might apply to the R-390, but Ham Radio
magazine ran a couple of articles about Collins PTOs, that might provide
some background information or help.

Bill Orr had an article in the December 1969 issue about the PTO in
the 51J-series receivers, including if I recall properly how to get
the PTO out and open it up.

Then, there was an article in the December 1974 issue about the PTO
in the 75A4.

The only Collins PTOs I've looked inside of were some 1 to 1.5MHz
ones I got at a hamfest decades ago. The circuit was really simple,
of course the mechanics were what made them really good.

Michael VE2BVW