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Re: [TenTec] TT Eagle tuner spec: SWR v. impedance range?

To: tentec@contesting.com
Subject: Re: [TenTec] TT Eagle tuner spec: SWR v. impedance range?
From: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Reply-to: geraldj@weather.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 08 Jan 2011 15:27:38 -0600
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
We wish that to mean that the tuner will match at 10:1 SWR circle at all 
phase angles and frequencies and greater mismatches for some phase 
angles. Any given tuner has better chances of making good matches for 
wild loads on bands other than 160 and 10m. On 160 certain loads require 
more L and C than can fit in the box, and on 10m certain loads require 
less L and C than those large components needed for 160m can be reduced 
to. Low impedance loads are toughest on 160m and high impedance are 
toughest on 10m. One sort of happy solution is to change the feed line 
length in 1/8th wave increments to see if the load can be moved to a 
handier impedance. Another is to use fixed L or C in shunt or series to 
expand the range of the tuner and another is to use a ferrite cored 
conventional transformer to raise or lower the impedance on some bands. 
Sometimes some manual reconnection is handier than finding a more 
compact tuner with a wider load impedance range for 160m.

73, Jerry, K0CQ

On 1/8/2011 10:56 AM, shristov wrote:
> "dbp tds.net"<dbp@tds.net>  wrote:
>> The Eagle spec sheet for the antenna tuner says: "Matching impedance range: 
>> 10:1 SWR typical".
> That would be a very good way of specification, if only it was true.
> "SWR<= 10" is a unambiguous reference to a set of complex impedances,
> i.e. those inside a certain circle on a Smith diagram.
> But the impedance range of LC tuners is not confined to a circle
> (or any other simple figure) on the Smith diagram, so a specification
> as given above has NO definitive meaning.
> It's just another way of saying that sometimes the tuner will match to SWR of 
> 10,
> and sometimes it will not.
> 73,
> Sinisa  YT1NT, VE3EA
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