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Re: K2: Heat On Digital Modes

Posted by Don Wilhelm-4 on Sep 26, 2010; 5:03pm
URL: http://elecraft.85.s1.nabble.com/K2-Heat-On-Digital-Modes-tp5572168p5572335.html

  Jon,

I do not believe your condition has anything to do with digital modes,
but rather sounds like you have a power control problem - it should not
heat up that it is too hot to touch, and not as fast as you indicate.
I assume a K2/100.  If so, please use an external wattmeter to determine
just how much power it is really producing.  Also, see if the power
control properly controls the power?  I am suspecting that you have some
problem with the KPA100 wattmeter (like damaged diodes from a lightning
surge) and it is developing full uncontrolled power output, which for
some KPA100s can be as high as 180 watts.

73,
Don W3FPR

On 9/26/2010 11:42 AM, Jon Perelstein wrote:

> This is a follow-up to a post about two months ago.
>
> I'm still getting pretty high heat on my K2 when running digital modes such as
> PSK, Olivia, etc.  Per the recommendation of Don and a few others, I'm adjusting
> the K2 so that my desired power output is set on the Power control (25 watts),
> and then I'm setting my input gain (using a Signalink) so that (a) I do not
> exceed that power on the display and (b) I have one bar on the ALC.
>
> Despite that, the K2 heats up rapidly.  After one or two transmissions of 2-3
> minutes each, the K2's fan will stay on high speed for all transmissions and the
> top of the K2 is hot to the touch.  As it heats up, people notice drift of +/-
> 20 Hz (on 20 meters) as the rig warms up during transmit, even with the fan
> kicking in.
>
> The K2 does cool down on long receives, which indicates that the fan is having
> some impact, but obviously not enough.  For now I have aimed a desk fan at the
> K2 when operating digital and it has reduced the heat and the drift.
>
> Is all this normal for digital on the K2?  Are there things I should be looking
> at that might perhaps be indicating a problem in my build?
>
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