I have been using the 253 tuner for several years now, though its no
longer in production. It was discontinued several years ago and it
cost around $1200 (I think); I got mine for much less in a UK company
bankruptcy sale, brand new, but ex-demo and not working (only a loose
coupling screw on the coil drive motor). Yes, it covers all bands, and
is directly connectable to the OMNIs and Herc II amplifier (probably all
TT amps as well) TT supplied me with a cable for this. BUT see B.
below...
(i) there is an official mod to reduce the RF power needed to tune up -
I did this and it generally tunes with less than 50 watts
(ii) there is also an official mod to improve the SWR accuracy between
the tune condition and the in-use condition. Previously there was a
clear discrepancy between the two (on my version anyway). This mod
requires some fiddling around to set up a new ground connection for the
SWR bridge. After the mod, the indicated SWR is more or less the same
under tune and in-use conditions.
Problems: A. The band data is stored in an e-squared prom chip which has
a finite life. (100k cycles). Its not difficult to replace; they cost in
UK around $15 each. This reflects the difficulty of getting the things
(from a strictly trade outlet) and my location outside the US. They
ought to cost less than ten bucks in the US, where they are made. TT
certainly have them.
B. It covers all bands, but normally only remembers settings
for some of them. Note that the band data output from the radio is the
same on some bands. Solution: use the antenna selector switch. Each
position can hold several different settings. I store band info for CW
on 160/80/40/20/10 on position 1. I store SSB frequencies for these
bands on position 2. Finally I store my preferred settings for the WARC
bands on position 3. In every case I store data for a target frequency,
e.g. 14025 for 20 CW, 14200 for 20 SSB. Choose your own favourites. If I
need to adjust within a band I use the up/down buttons.
Position 4 is used for the dummy load; the ATU is programmed to by-pass
in this position.
Of course, this means three cables to a main antenna selector switch.
I use a couple of old Heathkit coax switch boxes.
C. Since I did the SWR mod and also replaced the CPU chip
with the one with the latest software (thanks, TT) I have noticed an
occasional failure to return exactly to a programmed setting. I think
this is partly my fault - I re-wired the shack and need to make up some
longer cables so I can use the antenna selector switch again. Right now
I'm stuck with position 1.
I am very lazy. I like the 253. It replaced a home brew Ultimate
Transmatch and finally eliminated RF in the shack. Its worked well for
me. It gets a LOT of use; I run 400w through it into a 40m dipole on all
bands 80-10, via 20 ft of coax, a Centaur balun and 60 ft of heavy duty
ladderline. (160m is out of its range with this setup). When I used a
40m quad loop I had a match on 160 as well. A DXCC score of 357 is not
too bad, I guess. (Before you ask, I do not use the internal balun
because of the problems inherent in getting ladderline through two
solid brick walls).
If the price is right, then the 253 is an interesting device. Currently
still available competitive products seem to use switched
inductors/capacitors; the 253 has a roller coaster and a bank of
switched capacitors. Its an L-network and therefore electrically
a 238 with very elaborate control system, including a vacuum relay to
reverse the L.
Confession: I really wanted a 238; there were none in UK at the time, so
I took the one and only available 253 (mainly because TT do not have a
rice device limited support policy and I knew I could get help if
necessary). Get a 238 and don't be as lazy as me.
Hope these notes are some help. Now can someone tell me how to
reduce/eliminate the clicks/thumps from my Omni-V speaker when
working fast QSK ?? Its not too bad on my phones, but I like to use the
speaker from time to time. That reminds me; there is a brief and
almighty blip of RF output when I press the PTT switch on the TT desk.
mike. Is the switch that noisy ?
On 19-Jul-99 John Dvoracek wrote:
>
> I would really appreciate any info on when Ten-Tec ceased producing
> the 253
> automatic antenna tuner, what the price was how well it worked
> (reliable?),
> and if it covered the WARC bands. Thanks and please reply to
> jdvoracek@vvm.com .
>
> 73, de ke5c, op John
>
>
>
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E-Mail: jac <patents@dx0man.prestel.co.uk>
To: <tentec@contesting.com>
Date: 19-Jul-99
Time: 21:58:24
This message was sent by XFMail
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