[TenTec] Corsair Model 561 PTO (incl. caution about petroleum lubricants)

[Mike Hyder -N4NT-]

Hi, Mike--

What you describe sounds precisely like my experiences with all Ten-Tec
PTO's when the grease inside them has become old, sticky and gummy.  The
solution is to remove and disassemble the PTO, then thoroughly clean the
grease from all its parts.  Once clean and dry, all moving parts ought be
liberally regreased, the PTO reassembled and installed in the rig again.  On
Saturday I visited my uncle who has repaired clocks for many years.  I asked
him what lubricant to use on old clocks.  He said fish oil or a synthetic
lubricant.  He said, "NEVER USE A PETROLEUM BASED LUBRICANT ON BRASS!"  He
said that it will damage the brass by chemical reaction.  I never knew that!

Here are some tricks:
1. Using a pencil or Sharpie marker, label the feed-thru capacitors on the
side so you can easily determine how to reconnect the wires when you are
done.

2. The PTO's in Corsair models can be removed easily without removing the
front panel.  Here's how:
  a. Sit the rig upon its heat sink.
  b. Remove the main tuning knob and dial skirt.
  c. Remove the two screws beside the main tuning shaft along with the wiper
wires they secure.
  d. Remove any other screws that secure the PTO to the chassis (if any).
  e. Remove the PTO from the rig.

3. A screw-starter that will hold the screw will be of value both in the
removal and reinstallation of the PTO.

4. Disassembling the PTO is best done in a large, flat pan with a lip around
it.  This keeps parts from getting lost.

A very nice fellow has put the rebuilding instructions for the Ten-Tec
Century PTO rebuild on a website.  The PTO's are surely similar.  Here is
the link:

http://www.io.com/~n5fc/c21_pto.htm

73, Mike N4NT

----- Original Message ----- 
From: "Michael Shortland" <michaelgs at dsl.pipex.com>
To: <tentec at contesting.com>
Sent: Monday, July 26, 2004 12:54 PM
Subject: [TenTec] Corsair Model 561 PTO

> I have just acquired a Corsair Model 561.  Fine rig, but I get PTO
> instability on CW all bands.  Not slow drift, but frequent step changes up
> and down of a few 10s of Hertz over long periods.  Also, warbling can be
> heard as band is tuned.  Have checked that the regulated voltage supply is
> steady.  Frequency of PTO is not affected by vibration.
>
> Any suggestions on the source of the problem and a fix, please?  How do I
> remove the PTO to check components, solder joints, etc?
>
> Regards
>
> Mike G0EFO
>
> Guildford UK