[Elecraft] KPA100 - K2 #4498

[F5UL]

Hello all!

The cKPA100 arrived Wenesday and was finished and going through full test 
yesterday.

It was perfect and I stoped just before instaling the shield (it was tested 
first direct with the K2 and after was mounted in the separate EC2 with trhe 
same good results, from 115w on 3.5 to 82 watts on 28, CW and SSB).

This morning I mount the shield with all verifications, install the KPA 
definitly in the EC2 and last verification with dumy load. Work fine under 
11 watts, and at 20 watts dialed, the 25 amp (normal not switched!) supply 
goes down to 0.7 volt, and sure the 20 amp fuse blow!

So I check the supply itself, all correct (it was working before withe a 
home made 200 watts PA), the K2 by itself is OK. I reopen the EC2 
dismentling the K2, remove the shield, and redo the resistance check : Q1 Q2 
collectors 18 k, bases 11.2 ohms J3 +lead >15 k J2, Q9 and D13 all OK too.

I dismount the PC from the sink and do the resistance check again after 
visual check to see if anything has gone bad, Same results for ressistance, 
so what can I do?

To resume, the fuse blow when I turn on the K2 (sure, with the amp in 
service) power dialed over 11 watts (whatever, it blow with 11.2 or 100 
watts!). Another constatation is R21 going very hot, even starting to smoke!

Help please...
F5UL/Bob