K3 swr readings on 10m

[Dave-3]

Interestingly while over in england for the weekend installing My wifes K3 I
had a similar experience

I was interfacing the new DEMI 70MHz transverter which needed 5W drive at
10m

So i set up the transverter to use the antenna 1 connector. When producing
5W the K3 thought the SWR was 4.5 to 1. Inserting an swr meter between K3
and xverter showed that the swr was 1.1:1

as an experiment I engaged the atu, which not surprisingly convinced the k3
the swr was 1:1. The swr meter still showed 1.1:1

I then put the ATU into bypass mode and this time it showed swr of 1.1:1
rather than 4.5:1, which didnt make sense

Dave

G4FRE

>
> Message: 10
> Date: Wed, 5 May 2010 14:31:29 +0100
> From: "Geoffrey Downs" <[hidden email]>
> Subject: [Elecraft]  K3 - SWR on Tx Gain Calibration
> To: <[hidden email]>
> Message-ID: <AAF7700462664DBF8EDBDFB1B61730FA@Geoff>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> For some time I've been puzzled that, when doing a TX gain calibration
> either manually or with the utility, the SWR displayed was 1.0:1 on all
> bands except for 10m where it was 1.5:1. Yesterday my K3 (Ser. No. 266) had
> a meeting with a K3 (slightly earlier Ser. No.) belonging to David G4DMP
> (the owners met too!) and we found that his K3 was the same.
>
> Now here's the interesting thing. During tx gain calibration a 50 ohm dummy
> load is used and the ATU is in bypass mode. As an experiment David put his
> K3's ATU in circuit on 10m and pressed ATU Tune - result (unsurprisingly)
> 1.0:1. He then put the ATU back into bypass mode and held Tune as one would
> do in a tx gain calibration. Hey presto - 1.0:1! My K3 behaved in exactly
> the same way and now always displays 1.0:1 on 10m into the dummy load with
> the ATU in bypass mode.
>
> Presumably this is something to do with the ATU not being out of circuit
> when in bypass mode.
>
> 73 to all
> Geoff
> G3UCK  
>
>  
>
> ------------------------------
>
> Message: 11
> Date: Wed, 5 May 2010 08:39:34 -0700 (PDT)
> From: lstavenhagen <[hidden email]>
> Subject: Re: [Elecraft] K3 - SWR on Tx Gain Calibration
> To: [hidden email]
> Message-ID: <[hidden email]>
> Content-Type: text/plain; charset=us-ascii
>
>
> For what it's worth, I definitely can't replicate this on my K3. The ATU is
> definitely is bypassed when I select bypass on 10M (in both ANT sockets).
> Do you hear the relay clicking when you switch back and forth between bypass
> and inline?
>
> 73,
> LS
> W5QD
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K3-SWR-on-Tx-Gain-Calibration-tp5008783p5009531.html
> Sent from the Elecraft mailing list archive at Nabble.com.
>
>
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