[TenTec] Stabilizing drift in Corsair II PTO or any Ten-Tec PTO design...

[Jerry Volpe]

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 at 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