[Elecraft] KPA100 hot resistor...?

Mon Oct 27 12:46:01 2003

My first thoughts is that it may be normal. Power levels at the antenna 
out are measured in RF out watts and the resistor @3 Watts rating is 
pure resistance power levels, hot enough at 3 watts to burn skin off ... 
being in front of the fan may have been a deliberate design for 
cooling... not having a schematic I'd say maybe this is a voltage 
dropping resistor or part of a voltage divider network in which case it 
would be hot ... hope it is mounted at least 1/2 " off the PCB for long 
term reliability. However, this is just an uneducated guess Nate ...
73, Mike KD7YLA

Nate Lewis wrote:

>I was just doing the various last calibration steps to a new KPA100 when I
>noticed that R13 was uncomfortably hot.  This is the 3W resistor right in
>front of the fan.  When I move the K2 power from low power to 11w, it takes
>about 30 seconds for R13 to go from room temperature to painful to touch.
>Is this typical, or have I screwed up somewhere?  This is after doing bias
>adjustment, though I first noticed it during fan testing.
>
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-- 
73, de Michael Heit KD7YLA
"Real Hams do it at a high frequency"

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