[TenTec] Ig drift on amps

[Duane Calvin]

Yes, Ron, I've experienced the same symptoms in my 238B which I have not
opened it up to diagnose yet.  As I recall, it happens most often on 160m
and maybe 80m, but I can't swear to that.  It happens few enough times that
I haven't had to open 'er up to see what's going on.  Sorry I can't help
more than just confirming your symptoms.

	73, Duane

Duane Calvin, AC5AA
Austin, Texas
www.ac5aa.com  
 
-----Original Message-----
From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
On Behalf Of Ron Castro
Sent: Saturday, February 07, 2009 2:37 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Ig drift on amps

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 at ncn.net>
To: "Discussion of Ten-Tec Equipment" <tentec at 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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