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@bellsouth.net>
To: <tentec@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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