[TenTec] 238 Tuner Mod

[Denton]

Easiest way for me to rework a 229 tuner..
Take off top cover.
Take off the 4 screws holding the roller inductor and main tuning capacitor 
(bread slicer to us old timers) to the bottom of the chassis.
Take a folded towel and place it on top of the capacitor and roller 
inductor...to fill up the space between to the top of the tuner.
Replace top cover and secure with screws.
Flip tuner over, remove bottom cover. Plenty of room to work!
Be sure when replacing the ceramic caps not to stress the tabs on the 
capacitor switch too much!

----- Original Message ----- 
From: "Jack Mandelman" <modeler at bellsouth.net>
To: <tentec at contesting.com>
Sent: Tuesday, March 04, 2008 6:55 AM
Subject: Re: [TenTec] 238 Tuner Mod


>I made a similar mod to my 229B tuner.  However, instead of using
> doorknob caps I replaced the originals with 6KV 470pF Y5P ceramics.
> These capacitors are physically larger than the originals, having a
> thicker dielectric for increased breakdown voltage and larger plate
> surface area for increased current carrying capacity.  The drift problem
> was nearly completely, but not entirely, mitigated.  Complete
> disassembly of the tuner was unnecessary, since I was able to work in
> the tight space around the switch with small forceps.
>
> Now, I'm considering using the doorknob caps.  Would appreciate any
> suggestions about disassembly of the tuner for easier installation of
> the doorknob caps.
>
> 73,
>
> Jack K1VT
>
>
>> I few months back, I modified my TT 238 tuner by changing out the disc
>> ceramic
>> caps with surplus Soviet military doorknob caps, which dramatically
>> improves
>> the power handling capability on 160 and 80 meters.  Heating used to
>> cause the
>> SWR to 'drift', even at 100 Watts in some situations on 160.  The mod
>> worked
>> well, and if anyone is interested, I have all the details and pictures
>> on my
>> website at www.n6ie.com.
>>
>> 73,
>>         Ron N6IE
>>      www.N6IE.com
>
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