Two wires work even better. I've used small piano wire, AKA music wire.
Greasing the shaft where it passes through your wipers will reduce the
problems caused by oxidation and corrosion over the years (which would not
damage anything except the quality of the electrical contact.
73, Mike N4NT
----- Original Message -----
From: "k9ew - Ed" <k9ew57@gmail.com>
To: "QRP-L" <QRP-L@mailman.qth.net>; "TenTec List" <tentec@mailman.qth.net>;
"TenTec Contesting" <tentec@contesting.com>
Sent: Tuesday, October 25, 2005 12:11 AM
Subject: [TenTec] PTO HAND CAPACITANCE EFFECT - ELIMINATED
For anyone using an TenTec rig that has PTO tuning, here's good news... I
was rebuilding the PTO in my Argosy 525, and decided to try grounding the
tuning shaft to eliminate the sometimes irritating frequency change that
occurs as you bring your fingers near the tuning knob on the older TenTec
rigs. This might be more a CW issue, but perhaps it shows up in digital
operation also. I wanted some kind of a springy wiper contact, and I wound
up using a piece of #22 copperweld wire. I wrapped one turn around a small
drill bit to form a loop, and mounted it under the LEFT PTO screw on the
inner front panel. I had to make a couple of bends to get the wire to lay on
the larger diameter portion of the tuning shaft, making a half-loop at the
"wiper" end to ride on the shaft. This grounding wire must clear the dial
cord, but it must also avoid interfering with the outer front panel. It's
easier than it sounds. And the best part is that it works! There is
absolutely NO CHANGE in receive frequency no matter where my fingers are.
The next time you're doing a PTO rebuild, I highly recommend making this
simple mod.
73,
ed - k9ew
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