It's possible that the fixed capacitors in the tuning network, C15 - C20,
are heating on the low bands, much like the problem that has been discussed
on this list regarding the fixed caps in the 238 tuner. Another possibility
is heating in the L5, the core-wound coil which could get fairly hot under
long use which would change its inductance.
Ron N6IE
www.N6IE.com
----- Original Message -----
From: "Roy" <royanjoy@ncn.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, February 07, 2009 8:49 AM
Subject: Re: [TenTec] Ig drift on amps
"I seem to have a bit of Ig drift on the low bands, not so much if at
all on the upper bands.
I recently heard there can be an issue with one of the caps in the
tank causing this but didn't get any specifics on which one or what
to replace it with.
A google for Ig drift & the titan came up nil. Anyone have info to
help me out?"
Thanks.
Gary
KA1J
Gary,
Ig drift, and Ip drift for that matter on the low bands is, as noted by
others, usually due to changes in capacity of tank padder caps from heat.
Often times cheap, non-temp-compensated ceramic caps are used as tank
padders. I have replaced mine with quality, compensated 'transmitting
ceramics' or better yet with transmitting micas. Excessive drift
disappeared.
73, Roy, K6XK
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