[Elecraft] K3 Suddenly Putting Out Only 25 watts at 100 watts indicated

[Bob McGraw K4TAX]

Someone suggested performing 2 tone tests.  Seems reasonable.

I tried that with my K3S into a dummy load and an a RF sample fed to my 
RSP1 receiver using HDSDR  software.   I find that it does indeed 
display the IMD products from the 2 tones.  I now need to study the 
results a bit more to evaluate the test.

{Oh, don't forget to set 2 TONE to OFF mode or you'll get a surprise 
when you jump into that SSB rag chew group.  The comments won't be very 
kind.}

73

Bob, K4TAX


On 12/13/2018 1:03 PM, john at kk9a.com wrote:
> It would be nice to know what conditions caused this FET failure. Is there
> an easy way to know when this failure occurs other than getting crappy
> audio reports?
>
> John KK9A
>
>
> Peter Dougherty (W2IRT) wrote:
>
>
> This happened to me at the start of CQWW-SSB in October. My K3s is finally
> enroute back home after a 6 week stay in the Elecraft Repair Department
> with a blown FET in the HPA, cause unknown. And I know I've been told I'm
> not the only one to suffer this failure, and it sounds like this is now a
> known issue.
>
> Does anybody have an idea as to what could be causing these FETs to fail,
> or steps to consider to lessen the chances of it happening? I can't speak
> for anybody else, but I baby the heck out of my gear and was shocked to
> discover it failed, when feeding directly into a KPA-1500.
>
> ----------------------------------------------------
> Regards,
> Peter Dougherty, W2IRT
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at
> mailman.qth.net] On Behalf Of Wes Stewart
> Sent: Wednesday, December 12, 2018 4:55 PM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] K3 Suddenly Putting Out Only 25 watts at 100 watts
> indicated
>
> If you have another receiver, run a two-test and listen to the K3 output in a
> narrow BW.  Ideally, the two tones will be considerably stronger than the
> first
> pair of sidebands.
>
> I suspect they won't be, you'll have a lot more than two and you have a blown
> FET in the HPA.
>
> Wes  N7WS
>
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