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Ward Silver and Tom, W8JI wrote, and put out on the Topband Reflector
what is below the line. My comments:
I know they are no longer made, but the TenTec Models 229 and 238
tuners are not all bad. Being L-network tuners, they cover a very
wide range. They have an internal 500 pf 2 KV air variable capacitor
and padding in four steps of 440 pfd, so the internal capacitors can
have a total value from 40 to 2260 pfd. Also both models have an
external terminal for another 1000 pfd parallel padder for 160 meters
which raises the total shunt capacitance up to 3360 pfd!
The roller inductor is good quality and covers 20+ uhy.
So, although QST cannot review it, these models make sense, and have
the ability to be used effectively on 10 through 160 meters.
There is a Collins model 180-U reversible L network tuner in a smaller
box that is about the same, but only up to about 10 uhy and 1500 pfd.
Using a coaxial T on the capacitor side, another 1000 or 1500 pfd can
be paralleled across the internal capacitor. They were rated, by the
military, for 500 watts SSB and RTTY, and have been used for a KW by
hams. The model 180-S has a vacuum variable of similar construction,
but uses plugs and jacks to add capacitive padders, instead of a
ceramic rotary switch like the 108-U and TenTec models.
I am also reminded that someone made a "Unique Wire Tuner" It had a
series capacitor and shunt inductor L-network inside. It could be
rewired to shunt capacitor and series inductor, if one is willing to
add capacitance externally across the internal 2 KV air variable, it
would work OK on 160 as well. The current in the coil would be the
limiting factor. It should be good for 500+ watts.
Hope this helps.
73 George K8GG
______________________________ Reply Separator _________________________________
Subject: Re: TopBand: QST Antenna Tuner Review
Author: W8JITom@aol.com at BC_INTERNET
To: <topband@contesting.com>
Date: 2/25/97 11:59 AM
In a message dated 97-02-25 10:19:42 EST, hwardsil@wolfenet.com (Ward Silver)
writes:
<<
To be sure, there are some tuners that are better than others. N4XM's
looks like the best of the bunch. But a little extra work outside means
less expensive shack heating inside.
>>
Actually if you added higher value capacitors to any of the other T network
tuners they would work as well as the Xmatch.
If you read carefully, you will see it is a T network tuner with large C.
That hurts
ten and fifteen meter performance, but improves 160 a whole bunch.
The problem with most T network tuners is they do not have enough
capacitance,
so Q is too high on 160. This was all covered in rec.radio.amateur.antenna
<<
Meters, switches would not hurt, so what about the Heath SA2060?
Anyone have performance data?
>>
Look at the amount of capacitance. That will govern 160 performance
into low impedance or capacitive reactive loads.
73 Tom
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