[Elecraft] Underside of K3 getting very hot when transmitting

[AD6XY]

It is normal - depending on what you mean by "very hot". Very hot to the
touch could be 60C. Very hot to a PA device might be 90C or more. It is a
good sign your transistors are thermally bonded to the case.

I am not sure you are really supposed to use high duty cycle modes for
extended periods like this. The manual mentions reducing power on 100% modes
like FM. Using the bottom of the case for cooling generally works OK for low
duty cycles but might need help for 100% modes.

My 2m and 4m XV transverters use relatively inefficient PA modules and so
also get hot during extended contesting. I found a small waft of air from an
appropriately positioned computer fan sufficient to prevent excessive
heating. You might try this with the K3. It takes very little air because
the surface area is large and you are only dissipating a few watts.

Mike



Jens Køster wrote:
> 
> My K3 100W ser. 1343 gets VERY hot on the underside where the PA
> transistors
> are connected to the chassis. I´m testing at 100W FM into a dummyload for
> about 3-5 minutes.
> 
> Is that normal?
> 
> Vy 73
> 
> Jens
> OZ9MZ
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
> 
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
> 
> 

-- 
View this message in context: http://n2.nabble.com/Underside-of-K3-getting-very-hot-when-transmitting-tp1082012p1082061.html
Sent from the Elecraft mailing list archive at Nabble.com.