Just a coil in a plastic box solves most of the problem for an awful lot
less money.
If you can get by with manually switching the coil in and out, rather than
using expensive relays, you really can make it cheap.
-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of george fritkin
Sent: Tuesday, August 17, 2010 9:46 AM
To: geraldj@weather.net; Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] swr
You are just moving the match losses out to the $250.00 box at the antenna.
You are reducing the SWR losses in the coax. So for maybe 1/2 DB coax loss
you can spend the $250.00. It does not make the 43 foot radiator a better
antenna'
George, W6GF
--- On Tue, 8/17/10, Dr. Gerald N. Johnson <geraldj@weather.net> wrote:
From: Dr. Gerald N. Johnson <geraldj@weather.net>
Subject: Re: [TenTec] swr
To: "Richards" <jruing@ameritech.net>
Cc: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Date: Tuesday, August 17, 2010, 2:41 AM
On 8/16/2010 11:16 PM, Richards wrote:
> On 8/16/2010 10:18 PM, Dr. Gerald N. Johnson wrote:
>> A 43' vertical is a serious mismatch on 160 and 80, its too short,
>> has a low radiation resistance and lots of reactance. That makes a
>> tuner run a high loaded Q and have lots of circulating current in
>> its circuits.
>
>
> Agreed. That kinda sums it up nicely.
>
>
>> I don't know what is in the $250 box, likely a loading coil with
>> some sort of switching like a series resonant circuit for each band
>> to select the right amount of loading coil. There wasn't a manual
>> available for it on line to learn more.
>
>
> I could not find any details, either. I am thinking I favor Mr.
> Salas's design - it is open, and apparently has the imprimatur of the
> QST Editorial Board. It looks, good, too.
>
At the moment, I have a disagreement with the QST technical editor. In
the April QST he wrote that you can't make a parallel transmission line
with impedance lower than 87 ohms. That shows he's using the wrong
formula for characteristic impedance of a parallel wire line that ARRL
has been using wrong for all recorded history. The simple formula he
uses was replaced in other radio handbooks commercial and ham in 1943
for low impedances. The simple formula is OK for impedances above 250 or
300 ohms and about half the time it shows in reference works it noted to
be good only with the spacing is much much larger than the wire
diameter. I just published (again) a paper on that topic in the 2010
Central States VHF Conference proceedings (can be seen on line at
http://www.geraldj.networkiowa.com/papers/CSVHF2010/lztl1.JPG and
http://www.geraldj.networkiowa.com/papers/CSVHF2010/lztl2.JPG a repeat of
when I published in the VHFer on the same topic in 1966. I suppose I
should submit it as an article in QST. I see in the latest QST that Ed
Wetherhold is fighting with league publications on the sign of return
loss numbers and is getting the same results as tilting with a wind
mill. A Spanish wind mill at that. Perhaps HQ will read the CSVHF
proceedings and correct their ways. Perhaps not.
> ================================== JHR
> ==============================
>
73, Jerry, K0CQ
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