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


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[Don Wilhelm-3]

Bob,

Are Q6 and Q7 oriented correctly?

If this KPA100 is the new design (ordered after November 2006), you
should have a blue toroid core at L16 and RFC1 (I am using these as
identification indicators, not for any problem).

If you have one of the early new design KPA100, you should also have a
.22 uf capacitor at C31.  A few early kits were shipped with the old
value of .031 uf.  If you have the new design *and* the old capacitor
value, you need to change C31 to the new value - Elecraft will send you
one on request.

If none of these conditions are true for your KPA100, let us know and we
can try again with your problem.

73,
Don W3FPR

F5UL wrote:

> 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
>
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> 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
>
>

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