[Elecraft] K3 bad TX

[AD6XY]

I had a similar problem on receive for a while - also transmit. It turned out
to be a fault in the VCO.  I found it using my spectrum analyser. If you
don't have one consider getting one. A panadapter will also show it. Hunting
around with another rig is not as good a method but should also work if that
other rig is clean itself - it will be hard to find a rig as clean as a
properly operating K3 though.

I am suspicious as I would not expect both rigs to have VCO faults. It might
well be something else like a stray mganetic field or PSU issue. If it is a
VCO fault, your K3s should show it on both TX and RX. You can use your
signal generator to produce a strong carrier and tune for the spurs. If you
do not have a signal generator a crystal oscillator would do as well. If it
is only on TX, it is not the VFO.

There is a mod for the older VCOs you ought to do but it is not directly for
this problem. My faulty VCOs spurs were - I think 30-40 dB down and the
phase noise was pretty bad - I have an analyser plot of it somewhere. 

To fix it I swapped over the VCOs between sub and main, it not being very
practical to send stuff back when you are outside the US and with this sort
of thing the instability might not show up in a different K3. The second VFO
which was a later version is very very clean, there are a couple of spurs
either side of the carrier but a long way down.

Good luck fixing it.I just wish all the other people out there cared as much
as you do about their transmitted signals as I come across some really bad
ones on the bands - usually from overdriven linears.



Toni Lindén wrote:
> 
> I was using SO2R with pair of K3s' and had similar reports with both
> radios, so I guess it's not the amp issue. The bands where I got
> reports were 20M and 15M (on 10M were no propagation and maybe 40M and
> 80M were too noisy to notice the 2nd sigs).
> 
> All antennas are OK and no difference was noted with antennas.
> 
> 73 de Toni, OH2UA
> 
> 
>>Tke the amp out of the equation and see if you still have the issue. Try a
>>different antenna and check the SWR. I would suspect one of those to be
the
>>issue. At least it will eliminate some variables.
>>
>>Dan AB3EN
>>
> 
> Toni Lindén wrote:
>>
>> Hi!
>>
>> I was trying K3 for first time in SAC contest a couple of weeks ago.
>>
>> During the contest I got multiple reports that besides of my run
>> frequency, I also had other reasonable strong signals "around the
>> band".
>>
>> It cleared out that I had at least one other signal about 7kHz away
>> from my actual freq. It was quite strong, maybe 40dBs down from my
>> running freq.
>>
>> Have anyone else had similar problems and do you have any suggestion
>> how to fix this?
>>
>> I was using only about 60 to 70 watts drive for the amp and amp was
>> not pushed over. The same appears on both, CW and SSB. Radio has the
>> most resent FWs available via K3 utility SW.
>>
>> I'm planning to take K3 with me to CU2 for CQWW, but after getting
>> such a bad reports about "my 2nd pileup" on the same band, I'm not
>> sure if I'm willing to make such an interference to others on CQWW...
>>
>> So if anyone has any advice, I'm more than pleased to hear!
>>
>>
>> 73 de Toni, OH2UA
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