[Elecraft] K3 - Strange problem on 10 Meter SSB with power out

[WA6L]

The problem has been consistent across many configuration changes.  TUN PWR
is set at 100, though I tried it at several settings.  Power-per-band is not
active.

To test, I use the built-in 2-tone generator that you can enable in the
configuration menu.  That is very handy for testing audio modes.

CW provides full and measured power across all bands.  On 6m through 20
meters there is full and measured power on voice and data modes.  On 30m -
160m there is approximately 50 watts on voice and data modes.

Measuring PEP with a scope at the input to the roofing filters with the
2-tone generator and TUNE selected shows approximatey 4V peak on the higher
bands and approximately 2.25V peak on the low bands.

I would be interested to know the details of other similar problems.  Like I
said, at this point I am awaiting and RSA for return to the main office for
troubleshooting and repair.

Thanks,

John, WA6L



Alexandr Kobranov wrote:
> 
> Hi John,
> 
> can you - and the rest of suffering by this problem - put here some 
> more details about your setting:
> - POWER per Band active?
> - TUN PWR -nor- or any value defined?
> 
> Just to have complete picture.
> 
> Did you try to chenge some settings with some change in behaviour?
> 
> Thnaks,
> Lexa, OK1DST
> 
> 
> 
> WA6L napsal(a):
>> 
>> I have been having a similar problem on 30m through 160m.  Output is fine
>> on
>> CW on all bands.  On SSB, I am gettting only about 50 watts on those low
>> bands.
>> 
>> It appears to be hardware related, at least in my case.  I have been
>> doing a
>> lot of remote troubleshooting with Gary Surrency, and at this point and
>> awaiting my RSA for repair service.
>> 
>> 73,
>> 
>> John, WA6L
>> 
>> 
>> williamsonr wrote:
>>> If this has previously been discussed - please forgive me.
>>> This weekend ten meters was "open" (as much as it could be at the bottom
>>> of a cycle) and the 10-10 contest gave me a great opportunity to try out
>>> the 10 meter band on my recently completed K3 #1318(latest firmware). 
>>> All
>>> seemed well until I noticed that my power output on SSB was down as
>>> indicated on the K3 power meter and where I normally see 100 watt pep
>>> output on my tuners average reading meter.  So I grabbed my Bird 43
>>> (with
>>> PEP option) and a dummy load.  Sure enough, only about 50 watts PEP even
>>> though the control on the K3 is at 100?  Placed the K3 into tune and
>>> 95-100 watts out?  Go back to SSB and now the PEP power is back where it
>>> should be at approx 100 watts PEP.  After a few more SSB transmission -
>>> low power again(still connected to the Bird and dummy load).  This went
>>> on
>>> for a while as I checked and re-checked all of my mic and comp settings. 
>>> All other bands worked correctly.  Power supply not current limiting,
>>> all
>>> connections/cables good (connection to my stati
>>>  o!
>>> !
>>> n ground verified), fresh battery in my studio mic, SWR on ten meter
>>> antenna below 1.4:1 etc. etc.  Took the LPA heat sink bottom cover off
>>> to
>>> make sure the LPA transistors were making good thermal contact.  (I had
>>> added a spot of heat sink compound to each transistor during my assy
>>> process) There was a clear outline of the TO-220 transistor and an even
>>> film of compound indicating good pressure and contact.  Put everything
>>> back together. Haven't seen the issue again - yet?  But I am not
>>> convinced
>>> I did anything to make it go away?
>>>
>>> Anyone else had this experience?
>>>
>>> Rodger
>>> N4NRW 
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>> 
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