Re: K3 power reduction due to high SWR

Posted by Vic Rosenthal on Apr 06, 2012; 4:24pm
URL: http://elecraft.85.s1.nabble.com/K3-power-reduction-due-to-high-SWR-tp7439053p7443496.html

I am not sure I know how to do this. I have a device that I made
<http://www.qsl.net/k2vco/sniffer/rfsniffer.html>
to measure current but it gave me anomalous results when I tried it on the matchbox. I
found that when I measured the currents about 4 inches from the matchbox they were equal,
but when I measured them two feet away they were significantly different. So there is
something I don't understand about this process.


On 4/6/2012 9:16 AM, Geoffrey Mackenzie-Kennedy wrote:

> Vic,
>
> Before you write off "truly balanced tuners" in favour of the T-network + balun <g>, it
> would be interesting to measure and compare the current in each wire of the feeder (while
> transmitting a carrier) when using the Matchbox and then the T-network + balun?
>
> 73,
> Geoff
> LX2AO
>
>
> On April 05, 2012 18:28 +0200, Vic K2VCO wrote:
>
>
> <snip>
>
>> But here is the surprising part: I expected that the Matchbox would provide better
>> balance, which would reduce radiation and pickup from the feedline. To test this, I
>> coupled a grid-dip oscillator to the feedline about 20 feet from the tuner.
>>
>> To my great surprise, the signal from the oscillator was much weaker with the T-network +
>> balun than with the Matchbox!
>>
>> Signals the same, 'noise' weaker. So much for the need for 'truly balanced' tuners!
>

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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