SWR difference between 2 different K3's

[Richard Thorne-4]

I have a strange swr issue I'm trying to resolve.

I have two K3's for an SO2R setup, lets call them K3-A and K3-B.  On 40
meters the swr that the K3 displays on K3-A indicates what is to be
expected 1.5:1 at 7.001 and 2.0:1 at 7.105, however on K3-B  the K3
displays 1.0:1 at 7.001 and 2.7:1 at 7.105.

I'm using the same exact coax to connect to both rigs and I'm going
directly to ant port 1 on both rigs.  Neither rig has the ATU in line
(K3-B doesn't even have an internal ATU).  The antenna is a 2 element
40m yagi.

I've used an external Daiwa swr/power meter which agrees with rig K3-A's
swr  when connected to either radio.

So it appears that the displayed swr on rig K3-B is giving an incorrect
reading.

Any ideas?  Is it time to calibrate the wattmeter?

Thanks

Rich - N5ZC
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[Michael Walker]

Hi Rich

I think you have your answer and the B rig needs some calibration.

Mike va3mw



On Sat, Jul 19, 2014 at 8:10 PM, Richard Thorne <[hidden email]> wrote:

> I have a strange swr issue I'm trying to resolve.
>
> I have two K3's for an SO2R setup, lets call them K3-A and K3-B.  On 40
> meters the swr that the K3 displays on K3-A indicates what is to be
> expected 1.5:1 at 7.001 and 2.0:1 at 7.105, however on K3-B  the K3
> displays 1.0:1 at 7.001 and 2.7:1 at 7.105.
>
> I'm using the same exact coax to connect to both rigs and I'm going
> directly to ant port 1 on both rigs.  Neither rig has the ATU in line (K3-B
> doesn't even have an internal ATU).  The antenna is a 2 element 40m yagi.
>
> I've used an external Daiwa swr/power meter which agrees with rig K3-A's
> swr  when connected to either radio.
>
> So it appears that the displayed swr on rig K3-B is giving an incorrect
> reading.
>
> Any ideas?  Is it time to calibrate the wattmeter?
>
> Thanks
>
> Rich - N5ZC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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[Richard Thorne-4]

Thanks for the ideas guys.

I've emailed support at Elecraft to see what their thoughts are.  I did
some additional testing.

I connected K3-B to my KPA-500/KAT-500 combo and I'm finding that the
K3-B sees a 1.5:1 swr while driving the KPA-500.  The SWR of the KPA and
KAT swr meters both measure near 1.0:1.  All other bands show 1.0:1
while driving the amp.  K3-A sees a 1.0:1 SWR on 40m while driving the
KPA-500.

Something is up with measuring SWR on 40m with K3-B, even after
calibrating the wattmeter.

Rich - N5ZC

On 7/19/2014 7:10 PM, Richard Thorne wrote:

> I have a strange swr issue I'm trying to resolve.
>
> I have two K3's for an SO2R setup, lets call them K3-A and K3-B. On 40
> meters the swr that the K3 displays on K3-A indicates what is to be
> expected 1.5:1 at 7.001 and 2.0:1 at 7.105, however on K3-B  the K3
> displays 1.0:1 at 7.001 and 2.7:1 at 7.105.
>
> I'm using the same exact coax to connect to both rigs and I'm going
> directly to ant port 1 on both rigs.  Neither rig has the ATU in line
> (K3-B doesn't even have an internal ATU).  The antenna is a 2 element
> 40m yagi.
>
> I've used an external Daiwa swr/power meter which agrees with rig
> K3-A's swr  when connected to either radio.
>
> So it appears that the displayed swr on rig K3-B is giving an
> incorrect reading.
>
> Any ideas?  Is it time to calibrate the wattmeter?
>
> Thanks
>
> Rich - N5ZC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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