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

[g7vjr]

Hi Joe, Bruce,

> Make sure the K3 ATU is in bypass mode

Thanks for the tip. I had the same doubts but double checked for this. The
ATU is bypassed.

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

The usual stuff - continuity checks on the patch lead and a digital
multimeter looking for 50 ohms on the dummy load.

> If the KAT3 is able to reach a SWR of 1:1 there is nothing wrong with 
> either the KAT3 or the K3/KPA3.

Thanks Joe. I am exploring the K3 main board in a bit more detail and think
I have a smoking gun; I can see that T4 (hidden under P70 to the ATU board)
has been scorched. The laminations have burned away on the windings and I
can see a burn on the primary turn inside. :-(

73
Michael G7VJR

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