[Elecraft] K3 output power failure.

[Clay Autery]

Alternatively, you might (if you feel comfortable doing so) open the 
unit up and inspect it for any foreign debris that may have made its way 
into the case, thus challenging the airflow design/volume/velocity.
The PA is in its own shielded enclosure, and thus relies heavily upon 
the fans to suck air through and out of the PA enclosure and overall 
enclosure).

Additionally, I would encourage you to hook the K3 up to a dummy load 
and check to see if the fans are running properly.  Do they spin at all 
when the unit is sitting at idle (PA somewhere around 36C or so in my 
stack).  Then, set power at 100 W and Press and Hold the XMIT/UNE button 
to engage tuning ops in CW mode.  As the PA warms up, the fans should 
start to spin up as indicated by warm airflow increasing in temperature 
and velocity out of the fans on the rear panel.

_*WARNING:*_  Make sure VFO Display is showing the PA temp in the 
display and WATCH IT CLOSELY....  If the fans don't start spinning up 
from slow speed by 40 or 41, tap XMIT and stop the TUNE procedure.  IF 
you forget to tap XMIT, you will put the PA into protection mode at some 
point, and MAY WELL DAMAGE THE PA, et al.

If the fans are not spinning at all, you MAY have dead fans or other 
pwr/signal issues to the fans.
IF the fans don't spin up as PA temp increases, you have issues that I 
am not qualified to help you troubleshoot properly or fix.

73,

______________________
Clay Autery, KY5G
(318) 518-1389

On 01/05/20 22:40, na5n at zianet.com wrote:
> Eric Rosenberg writes:
>
>> Everything seemed fine until this weekend's ARRL RTTY Roundup. After 
>> being on the air for about 4 hours, once again there no was RF output
>
> Eric,
> Sounds like an over temperature problem.  Especially if running RTTY 
> at near full power.  The high duty cycle of RTTY can cause the PA to 
> get very hot.  When it gets too hot, the radio shuts the transmitter 
> down for protection until it cools off in 15-30 minutes.  Too much 
> audio gain/ALC can cause the same.  Review the tech manual on 
> transmitter setup about over driving the K3 or external amplifier.  
> Just sounds like you're driving the K3 a bit too hard for prolonged 
> periods.
>
> GL es 73, Paul NA5N