[Elecraft] KPA100 Hi Current on 30M

[Robert Fanfant]

Is this a problem only on 30M?
-rob N7QT


----- Original Message ----- 
From: "Ken K3IU" <kenk3iu at cox.net>
To: "'Gottlieb, Jonathan'" <JWG at leonard.com>; <elecraft at mailman.qth.net>
Sent: Sunday, June 12, 2005 11:29 AM
Subject: RE: [Elecraft] KPA100 Hi Current on 30M


> Hi Jonathan:
>
> You may well have joined "the group." But first...
>
> Make sure that you can get at least 10 watts output on all bands with the
> KPA100 turned "Off" in the menu. Then you should recheck the power
> calibration procedure for the KPA100 unless you are very confident that it
> is correct.
>
> If both of those check out OK, then you are probably experiencing the same
> thing that several others (with you I think there are now 9) that are 
> having
> pretty much the same problem. Elecraft and the designer are working on the
> problem and I'm sure there will be a solution soon. In the meantime, one 
> of
> the things that has worked for some is to increase the capacitance at C80
> and C81 between T1 and the bases of the PA transistor. Some have changed 
> to
> 5600 pF, some have added another 4700 pF, and I ended up adding 2200 pF. 
> One
> ham in England who had the problem replaced C80 and C81 with new 4700 pF
> caps from Elecraft and the problem remained. He then purchased locally and
> installed replacement new metal film resistors to replace R19 and R20 and
> new 4700 pF caps to replace C80 and C81 and the problem was completely
> resolved for him. It suggests that the provided resistors may have enough
> inductance to resonate with the 4700 pF cap and create a "trap" at around 
> 10
> MHz.
>
> I encourage you to report the problem to Gary <support at elecraft.com> so 
> that
> they are aware that there is another builder with this problem.
>
> 73,
>
> Ken K3IU
>
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Gottlieb, Jonathan
> Sent: Sunday, June 12, 2005 12:12 PM
> To: elecraft at mailman.qth.net
> Subject: [Elecraft] KPA100 Hi Current on 30M
>
> Almost finished with my KPA100.  Power output is 100 watts on all bands
> except 30M where I get hi current display over 55 watts.  Any suggestions?
>
> Jonathan Gottlieb
> WA3WDK
>
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