You stated, "I have the transmission line connected to the balanced inputs
plus the extra wire going from one balanced terminal to the single-wire
terminal."
Why is the "...the extra wire going from one balanced terminal to the
single-wire terminal." ??? It seems to me that this 'extra wire' is
unbalancing a balanced feedline.
Re-read the TT instruction manual... Try removing the "extra wire"...
73, Larry - W1GOR
----- Original Message -----
From: <k8jdc@sbcglobal.net>
To: <tentec@contesting.com>
Sent: Saturday, September 24, 2005 1:15 PM
Subject: [TenTec] TT 238B Question(s)
> Hi all. I just bought a used 238B from a ham in CA. (I'm in OH). I
> received the tuner yesterday and have been testing it out. I've never
> used a 238 before, nor have I used a tuner with a roller inductor before,
> so those are new items to me. I thought I would post a few points and get
> some feedback from other 238 owners. (My testing has been primarily done
> with a 135ft dipole fed with 450-ohm balanced line. I have the
> transmission line connected to the balanced inputs plus the extra wire
> going from one balanced terminal to the single-wire terminal. Thus far, I
> have only run 100W thru the unit).
>
> 1. I opened the tuner and have not noted any burn marks or evidence of
> arcing or abuse. The only thing I noted visually was that the roller
> inductor wheel seems to be a little rough to me. The coil turns are
> perfectly smooth, but the traveling wheel doesn't seem to be as smooth as
> I would expect. The unit overall is in perfect condition cosmetically, so
> I don't see any signs that the previous owner abused it.
>
> 2. This tuner doesn't seem to be 100% healthy to me. The 1.5:1 bandwidth
> (>5% of the band) reported by ARRL in their QST review doesn't seem to be
> available in my unit. On 40m, 5% equates to about 350 KHz, or coverage of
> the entire band with 1.5:1 or better. My 238B is showing about 115 KHz,
> which is LESS THAN HALF of the expected value. Is this because I may be
> using an improper switch setting on the High/Low-Z switch? (For the
> record, my 40m settings were High #1, Cap @ 4.8, and Inductor @ 9.9 using
> the antenna I described above.)
>
> 3. I found tuning to be VERY difficult. I followed Tentec's
> instructions, but it was a lengthy process. Once I found matches on the
> various bands, they have been repeatable, so this difficulty should
> hopefully be a one-time problem, but it was not as intuitive as I
> expected. When I tried different switch settings on the High/Low-Z
> switch, it didn't seem to make much difference in most cases. Most of the
> matches that I found used either Low #1 or High #1 settings. Does this
> sound right? Finding a match in most cases involved several minutes of
> hunting.
>
> 4. The meter on my unit was totally out of whack in terms of accuracy.
> The SWR readings are way too low and the forward power readings were way
> low. I was able to adjust the pots to fix the forward power discrepancy,
> but I have not been able to fix the SWR reading. It is still too low. I
> have the set knob adjusted correctly and have tweaked C16 as described in
> the manual. While my radio and external Palstar meters are showing a 2:1
> VSWR, the 238B meter is showing about 1.3:1 or so. I can't seem to get it
> to get any closer.
>
> 5. The roller inductor is not nearly as smooth as I expected. I've
> already mentioned that I've never used a roller inductor tuner before, so
> I'm not certain what I should expect. When I spin the knob on the roller
> inductor using the little knob protrusion, it takes enough force that I
> usually move the tuner around physically. It doesn't spin effortlessly.
> I usually have to hold the tuner with one hand to keep it still while I
> adjust the inductor. If I just adjust the knob slowly using the entire
> knob instead of the little protrusion, this obviously isn't a problem. I
> have opened up the unit to inspect the roller inductor while I adjust it
> and can't really see anything out of alignment. What should I expect on
> this?
>
> I would appreciate your feedback on this. I hate to think that I may have
> bought somebody else's problem child. So far, the tuner is certainly
> usable, but I would have to say that it's not what I expected in terms of
> quality and performance.
>
> Thanks and 73,
>
> Dave / K8JDC
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