We all know that you can't just stick a balun on the input of a single ended
tuner like the 238. The tuner would have to be totally redesigned. Instead
of only one roller inductor, you would need two if one wanted to match the
same range of impedances. Fussing at TenTec because they don't just move the
balun to the input just doesn't make sense.
Secondly. The fact that you have a wire 1/2 wave length on 80 meters fed
with open wire line and the Johnson tuner can match it doesn't mean that it
will work for everyone. Feeder length is just as important and some lengths
will give even the Johnson problems. I know because I've got one setting
right here on the shelf. Of course one can always add to remove some feeder
to bring the impedance within range of the tuner. The impedance range of the
Matchbox and the Johnson is no secret. It's published in the manuals plus
QST ran an extensive test on tuners a few years ago. The old Matchbox was
near the top of the heap as far as loss goes. The TenTec wasn't tested.
If the 238 has some weak points it's these:
Hard to read coil scale.
Dial lights burn out often.
Flimsy construction.
Crank Crank and Crank
Good points:
Widest matching range on the market.
Matches looks and construction of other TT stuff.
Johson Matchbox Good points:
Built like a tank
Balanced output with no balun loss.
No coil to crank and crank and crank
No dial lights needed.
Johnson Bad points:
No 160 meter coverage
No antenna selector switch
KW model is huge
Doesn't match looks of TT stuff. (like I care)
Sometimes works ok on WARC bands, maybe.
So you may have noticed I hate to crank those inductors. That's why I'm
using a new Ameritron ATR-15.
Steve
N4LQ
----- Original Message -----
From: "Sherrill WATKINS" <SEWATKINS@dgs.state.va.us>
To: <tentec@contesting.com>; <reid.w.simmons@intel.com>;
<jmlowman@ix.netcom.com>
Sent: Wednesday, March 29, 2000 1:35 PM
Subject: RE: [TenTec] Re: Ten Tec antenna tuners
>
> As I understand it, the tuner problem is not because it is a T or an L
network type. The problem is because the balun is feeding
> power into a high reflected wave (swr). Moving the balun to the input
corrects this problem. If Ten Tec does not do this in their
> most recient model, then their tuner still has the basic problem. I have
used my Johnson Matchbox Antenna Tuner to operate o any
> h.f. band, as well on 10 meters, while feeding my 80 meter antenna with
excellent results. - 73's- Sherrill W. k4own
>
> --
> FAQ on WWW: http://www.contesting.com/tentecfaq.htm
> Submissions: tentec@contesting.com
> Administrative requests: tentec-REQUEST@contesting.com
> Problems: owner-tentec@contesting.com
> Search: http://www.contesting.com/km9p/search.htm
>
>
--
FAQ on WWW: http://www.contesting.com/tentecfaq.htm
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