[Elecraft] KPA500 repair

[Andy Durbin]

Well that's an interesting failure report.  I don't see any obvious single 
factor except for overheating of the entire PA module.

Was the fan functioning normally, air vents clear, and external airflow 
unobstructed?

"Capton tape on the "S" bracket is interesting.  Did they mean "Kapton tape on 
the Z bracket"?  Sounds like the fix I was going to attempt but the clicking 
went away as my KPA500 aged.

Andy, k3wyc
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[Elecraft] KPA500 repair

[n1ix]

My KPA500 is on the way back from Watsonville. Just in time for the Bouvet 
DXpedition 

I am trying to understand what might have caused the problem. Here are the 
details. 

 

Problem(s) found:

T/R circuit failure due thermal damaged diode D10 causing damage to traces and 
pads on LPF module.  Thermal damaged relays K3,K5,K7 on LPF module. (diodes 
physically near D10)   Amp clicking when getting hot. 

 

Repair(s) performed:

Repaired damaged traces and pads on LPF module.  Replaced diode D10 and 
K3,K5,K7 on LPF module. Replaced diodes D7, D8, D9 on LPF module as preventive 
measure.Added capton tape to “S” bracket to avoid amp clicking. 

 

Dave N1IX

 

 

 

 

 

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