[Elecraft] KAT500 and KAT500 Utility Question

[Wes (N7WS)]

Some of what you say is true, but has nothing to do with the problem.

Soapbox comment: Personally, I would (and do) rather use Heliax before I would 
ever use ladder line.


On 11/4/2015 2:21 PM, Ken wrote:
> The results almost totally depend on the length of the ladder line. At certain 
> lengths, it will act as an impedance transformer and could load your 80m 
> dipole quite well.  An 80m dipole on 160 will have a low impedance at the feed 
> point.   A quarter wave of ladder line will transform that impedance to a 
> higher impedance. A half wave of ladder line will give the same impedance (no 
> transformer effect.)
>
> If you have something near a half wave of ladder line, the 4:1 balun is 
> totally wrong since it will transform a low impedance to one 4x lower!
>
> Try it with a 1: balun and see if the SWR improves or not.
>
> As for actual, honest SWR readings, I assume that most meters are unreliable 
> in the actual readings when the SWR gets high, especially 10:1 and above.   
> They are really built to operate in the 50 ohm range, not 500 or 1000.
>
> BTW, IMO the KAT500 is one of the best tuners I've used and I've been building 
> or using them for over 50 years.
>
> Ken WA8JXM
>
>
>
> On 11/4/15 3:59 PM, Phil Hystad wrote:
>> First, this is a curiosity question about KAT500 utility only.  I don’t 
>> intend to use my antenna on 160 meters.
>>
>> I use the KAT500 with my 80-meter dipole fed by ladder line and a 4:1 Balun 
>> to Coax for last 20 feet.  This antenna works excellently in concert with the 
>> KAT500 for 80, 40, and 30 meter bands.  I don’t use it with other bands.
>>
>> This weekend, I was curious as to how close (or far) the KAT500 could bring 
>> the antenna in for the 160 meter band.  I knew that it would not work though 
>> I was wondering how bad it would be.
>>
>> So, as I expected, the tuning never closed in on a descent SWR, the best I 
>> saw on one test only was SWR about 49:1 as reported by the KAT500 utility.  
>> But, the BYPASS SWR reported was about 11:1.
>>
>> Further tests showed varying bad reports of incomplete tuned SWR while also 
>> showing a much lower BYPASS SWR (under 13:1). According to my own tests of 
>> the impedance for the antenna on 160 meters, the BYPASS SWR is bogus.
>>
>> So, I am assuming that unless the KAT500 reaches a tuned SWR value under 
>> 1.5:1 (or, whatever threshold I set), the BYPASS SWR is totally meaningless.
>>
>> 73, phil, K7PEH
>>
>>
>
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