I once opened up a telrex box balun to find it full of sand - or something
akin to it....was very distressed!
I may be able to help you with a lead on some parts for the TB6EM...let me
know what you need if any.
73,
Jim, K4OJ
----- Original Message -----
From: "Rush Johnson" <RushJohnson@carolina.rr.com>
To: <towertalk@contesting.com>
Cc: <w4qa@arrl.net>
Sent: Thursday, March 14, 2002 5:12 AM
Subject: [Towertalk] Telrex TB6EM
> Before I climb the tower and start taking things apart, I would appreciate
> any thoughts from those who have had prior experience with SWR changes on
> the Telrex TB6EM. I have had this particular tribander installed at the
> 100' level for about 5 years now with no problems until this past week.
We
> have had a good bit of rain recently -- so weatherproofing of connections
is
> the first thing I may check.
>
> 15 meters seems to be somewhat OK, but the SWR on 10 and 20 meters seems
to
> be out of line. On the low end of 10 meters (CW portion 28.025) -- the
SWR
> is over 3:1 -- dropping to under 1.5:1 at around 28.600 mHz. The SWR on
20
> Meters is about 3:1 at 14.000 mHz dropping only to 1.6:1 at 14.300 MHz.
The
> SWR is not lower than this on 10 and 20 -- 15 meters seems to be ok (1.1 :
> 1) on the low end -- rising to 2.8:1 at 21.200 mHz.
>
> Unfortunately, I can't find the original SWR curves when the antenna was
> installed -- and the auto-tuner may have been masking this issue for a
while
> now. However, it seems to me that I was experiencing less than 2:1 across
> all the bands when the antenna was first up. I recall the antenna being
> relatively broadbanded -- but used the auto-tuner in the 761 as a matter
of
> course.
>
> Of course, this could be: a) normal for the TB6EM, b) a feedline problem,
c)
> a balun problem, d) a trap problem -- etc. But, before I start tinkering,
I
> thought I would get some advice from those out there that either have a
TB6
> or have worked on them in the past. Also -- those that have not had a TB6
> but something similar -- maybe you can give me some troubleshooting
> guidance.
>
> Related to this -- I am wondering if the Balun that Telrex supplied with
> this antenna is a 1:1 balun or not? I would like to replace it with
another
> one sometimes in the future as a matter of maintenance anyway, but I don't
> know what characteristics the balun currently has.
>
> Thanks in advance for any advice!
>
> 73,
> Rush -- W4QA
>
>
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