[Elecraft] K3 output stage high SWR - fault-finding?

Sat Apr 7 12:48:48 EDT 2012

> The K3 shows a high SWR into a pure 50 ohm load or resonant antenna
> on both Ant 1 or Ant 2. I find that if I use an external SWR meter
> and connect the K3 to a dummy load through that, the SWR shows high
> on both the K3 and the SWR meter.

An external SWR meter can not show a fault with the transceiver - only
with those devices and connections further downstream.

 > I have checked the dummy load and patch lead.

How have you checked the dummy load and patch lead?  What convinces you
that they are "good"?

> I have the ATU module and find this is able to tune back to 1.0:1,
> but I'm pretty sure that's treating the symptom rather than the
> cause!

If the KAT3 is able to reach a SWR of 1:1 there is nothing wrong with
either the KAT3 or the K3/KPA3.  The function of any "tuner" is to
"treat the symptom rather than the cause".  To treat the cause one
would need to modify the antenna/load/lines to resolve the impedance
mismatch.

73,

    ... Joe, W4TV

On 4/7/2012 12:23 PM, g7vjr wrote:
> Hi guys,
>
> I have a problem with my K3 reading 5.0:1 or more SWR on tune into a 50 ohm
> load. I was alerted to this problem when I could not get the same SWR my
> analyser was showing for a new antenna, and quickly  discovered the K3 had
> developed a fault on all bands.
>
> The K3 shows a high SWR into a pure 50 ohm load or resonant antenna on both
> Ant 1 or Ant 2. I find that if I use an external SWR meter and connect the
> K3 to a dummy load through that, the SWR shows high on both the K3 and the
> SWR meter. I have checked the dummy load and patch lead. So, at a guess, the
> SWR reading on the K3 is correct and there is something wrong in the output
> stage of my K3.
>
> I have the ATU module and find this is able to tune back to 1.0:1, but I'm
> pretty sure that's treating the symptom rather than the cause!
>
> Any suggestions or advice on fault-finding this would be most welcome;
> sadly, I'm off the air!
>
> Many thanks,
> Michael G7VJR
>
> K3/100 no. 1904
> KXV3
> KAT3
> KRX3
> KDVR3
>
> --
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