[Elecraft] KPA100 Problem

[Mark Flavin]

Yeah. I did that too.  Im dreading changing the finals lol

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-----Original message-----
From: Don Wilhelm <w3fpr at embarqmail.com>
To: Mark Flavin <markf1952 at hotmail.com>
Cc: elecraft at mailman.qth.net
Sent: Sat, Nov 26, 2011 17:45:04 GMT+00:00
Subject: Re: [Elecraft] KPA100 Problem

Mark,

Have you checked the setting of the K2 CAL TPA menu?  It should read the  
same as the actual temperature of the PA transistor cases.

Let everything acclimate to the ambient room temperature (power off for 30  
minutes should do it), then turn power on and set CAL TPA to the room  
temperature in degC.

73,
Don W3FPR

On 11/26/2011 11:44 AM, Mark Flavin wrote:
>
>
>
> Well, I wanted to change the bridge diodes in the KPA 100 cause I was  
getting some wierd readings and hi swr readings so I decided to upgrade it  
while I had it apart.  I did the whole upgrade and now as soon as I put it  
in high power, even at only 15 watts, I get PA HOT readings.  I have checked  
all the parts values twice and did the calibration again including the C6  
adjust, the r26 and 27 adjusts and even pulled the finals to make sure they  
weren't shorted or anything.  Q3 and Q4 seem fine and are not cracked.  The  
voltages seem to be fine and I readjusted R6 bias as per book.  Whats wierd  
is as soon as I hit the key, even at 15 watts the fan comes on with the  
keying.  A dot gives a short fan wiggle and an dash gives a loneger fan  
activation.  Eventually it comes on and then I get the PA HOT.  The fan even  
responds to my voice on SSB.  I mean it comes on almost instantly.  I have  
checked the archives and am starting to suspect the finals.  I put on new  
pads on the transisto
>   rs and checked it all twice.  Resoldered all connections.  All works  
fine at 10 watts.  Im sure Im missing something but I dont seem to be able  
to find it.  Any ideas where I can check before I order new finals and go  
through that work again.  Thanks  MarkN5MF 		 	   		>