[Elecraft] KXPA100 Thermal Fault

[Edward R Cole]

Subject: [Elecraft] KXPA100 Thermal Fault
Message-ID: <e9b9.412e58f6.40fda858 at aol.com>
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I used my KX3/KXPA100 in the NAQP RTTY contest this weekend. The KX3 with
added-on heat sink worked very well; however, the KXPA100 repeatedly faulted
  with HI TEMPERATURE indicated on the KX3 at full output after prolonged
operating (lots of CQ'ing with short pause intervals). PA.X temp indicated at
  failure was around 60C...as it should. Shack temperature was around 70
degrees  F
Yes, I know all about digital modes and full power stressing amplifiers,
etc. What I want to know is how to mitigate this interruption yet run full
output. To that end, I have a couple ideas: what if I mounted the amp
vertically  so the heatsink fins "drew" cooler air through themselves via
convection?  Secondly, would a couple muffin fans mounted atop the 
cooling fins do
the job?
The net of this is that I'd like to enjoy the full benefit of having a
high-quality 100-Watt amplifier, regardless of mode or key-down time.

Bert N4CW/K1IMI
---------------------
Bert,

Using radial "muffin' fans to cool amps running digital modes is 
standard practise to save the amps from heat stress failures.  Just 
get enough to cover the surface area of the heat sink fins and you 
should find that it has solved the issue for the KXPA100.  Fin 
orientation is not important in that case.  Note the 100w amp in the 
K3 has two fans.

I run two fans on my 170w 2m linear and all my transverters have fans 
on the heat sinks.  I simply laid a 4-inch fan on top of my 150w 6m 
amp to keep it cool when running JT65.  I'm thinking of adding a fan 
on my 15w 900-MHz FM transceiver for a little insurance.

Note: I added a heat sink to my KX3.

73, Ed - KL7UW
http://www.kl7uw.com
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