[Elecraft] K3: SWR meter readings on 10m..mystery solved...

[Dave Perry]

John,

I noticed the same high SWR in bypass mode on 10M the other day.  I have the 
KPA500 and thus was wondering why the K3 was seeing up to a 1.7 to 1 SWR 
into the KPA500.  So I got home from work today and tried your solution.  I 
turned on the ATU and tuned into a 50 ohm dummy load.  When I went back to 
normal operation in Bypass mode, the SWR into the amp was back to 1.1 to 1. 
Thanks for the tip.

Dave, N4QS

----- Original Message ----- 
From: "VK7JB" <zendoc at netspace.net.au>
To: <elecraft at mailman.qth.net>
Sent: Monday, June 27, 2011 7:39 AM
Subject: Re: [Elecraft] K3: SWR meter readings on 10m..mystery solved...


> I've solved my mystery.
>
> I read in the archives that the KAT3 ATU is not completely out of circuit 
> in
> "bypass mode".  If I understand correctly, small values of L and C are 
> used
> to remove it functionally, but there is stray reactance that might
> contribute to the higher indicated SWR on some bands.
>
> So then I wondered if the KAT3 might need to be tuned at least once into a
> 50 ohm load for the "bypass" state to be correctly determined.  Made sense
> in my imagination, and thinking on it,  I realised I'd never tuned the ATU
> into a 50 ohm load before.
>
> So I did that - tuned the KAT3 to the dummy load on the bands where it
> previously indicated higher than expected in ATU bypass mode.  I let it do
> its stuff and find a match for the dummy load, then bypassed the ATU.
>
> Now, in ATU "Bypass" mode, the K3 reads 1.0:1 SWR into the same dummy load
> that it previously showed as 1.5:1.   Issue gone.
>
> 73,
> John
> VK7JB
>
>
>
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