[TenTec] 238 tuner on 160? (long)

[Tom Delker]

Lara & Mike Pagel (KU9W) wrote:

K1KY Note: Here are his questions and my replies as found with my unit
that is 4 years old.

> Hello all:
> 
> I'm looking for a tuner, one that will enable me to cover more of 160
> meters with my dipole and CTSVR antennas.  I have been thinking about
> pouncing on one of the #238 tuners that pop up here from time to time.
> 
> 
> I then reviewed the archive for the TOPBAND reflector and read 
> Someone favorably mentioned the #238, and that message was answered by
> another ham who offered an unfavorable analysis - mostly about the
> hardware.
> 
> Here is a portion of his message about the #238:
> ==========================================
> I don't like:
> * the anemic range (capacitor) switch--a conventional ceramic wafer easily
> destroyed by a hotswitch at moderate power.
Not a problem here yet, don't hot switch it!

> * the roller inductor--the coil form is ceramic, and the coil has a
> variable pitch, but the end plates are epoxy/glass PC board, and the roller
> tap wheel is skimpy. I wore mine out (the tap wheel literally wobbled on
> the shaft) and replaced it with a roller inductor and counter mechanism
> from a BC375E.
No problem here yet.

> * the sliderule dial mechanism--I repaired it countless times until I just
> threw it away, and it was not readable without the dial lights--nor was the
> meter.
No problem with the sliderule yet... lighting is a bit skimpy.

> * the SWR/power meter--very inaccurate and nonlinear. Good for relative
> indication only.
I might agree on this, especially at higher frequencies >21Mhz.  

> * the case--typical TenTec. Frequent disassembly lunched the end trim
> pieces--I threw them away. 
I find the case construction adequate.  Just be careful.

>Coax connectors were pop-riveted, but worked
> loose over time, creating intermittent ground connections. Replaced all
> rivets with screws, starwashers and nuts.
No problem here yet, but I would agree with this and will probably do
the 
same some day.

> * the balun, a 4:1 unit. Most baluns in single-ended tuners---if not
> all--are useless unless operated near the design center. This one smoked
> early on, and I tore it out. If you want to use balanced line, build a
> balanced-line tuner.
I recently obtained a Titan Amp, and managed to smoke some wires coming
off 
the balun because they were too close together.  The balun does get warm
when using on my 240' loop on 160m.  The unit will not tune my 80m
dipole 
on 160.  Am planning on using an external heavy duty balun soon.

> General construction reminds one of a homebrew project--useable but
> cheaply-made couplings, shafts. knobs and other components. In short: good
> electrical concepts, mediocre execution. This unit has helped dissuade me
> from buying other TenTec gear.
I think this is a bit extreme - I find the construction to be better
than most
tuners I have seen on the market.  There was discussion about tuners in
general
about 6 months ago here, and I believe it was generally said that the
L-network
circuit employed is the more favorable.

The isolation between the 4-position band switch leaves a little to be
desired.

In summary, I also use a 4229 tuner, which is a kit version of the 238,
and would
not mind purchasing another 238 sometime.  


-- 
Thomas M. Delker - K1KY CFO#395 - Smyrna / Gallatin / Short Mtn. TN
C.A.T.S. (W4CAT) - 147.30 (114.8) / 145.23 / 223.98 / 444.45 & 444.65
Stones River A.R.C. (K4FUN) - http://www.Voy.net/~rfi/stones.html
Tennessee Contest Group (K4TCG) - http://geo1.tdec.state.tn.us/tcg.html
Fistfighters United Nashville (NT4L) 146.955 (114.8)


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