Paul:
PTO's incorporate temperature compensating components that theoretically cancel
the drift changes of other components.... bringing relative stability. Trouble
is they are never perfect and they change their characteristics with age.
There is an alternative and that is incorporating a circuit that compares the
current tuned PTO frequency with a stable crystal standard and then provide a
slight control voltage to a compensating varactor. A simple concept that can
really make a difference.
Phil Chambley has an addon VFO 'Stabilizers' that can eliminate warm up and
temperature change drift on rig's using VFO or PTOs....Check out his site. His
addon board has been used successfully with PTO equipped Ten-Tecs... or so I am
told. If you send him an email he will send you an attacment detailing
installation instructions so you can see how easy it is to incorporate it into
your Corsair.
Phil Chambley
K4DPK
k4dpk@comcast.net
http://home.comcast.net/~k4dpk
By the way, using an external circuit to provide PTO stabilization is what
Ten-Tec used with the Scout to compensate for PTO drift problems. The Scout
though, did this via the main CPU and therefore had to share processor
resorces, timing, etc., so as a result there are some operating conditions with
a Scout where the drift compensation doesn't always work. Even so it is very
effective (I have two Scouts). Chambley's circuit is a fully dedicated design.
It has only one purpose and is always there so should work significantly better
than the one in the Scout.
It is a small board that mounts inside the PTO case and has four wire
attachments (if I remember correct). Totally non-destructive so can be easily
removed leaving no trace.
Hope this is useful information.
73,
Jerald, KG6TT
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