Posted by
Mike Geddes on
Jun 11, 2007; 2:31pm
URL: http://elecraft.85.s1.nabble.com/Strange-KPA100-behavior-tp449005p449009.html
Don,
I am not at home right now to look at K2, but will try and answer your
questions to provide additional information.
I am not sure what the K2 was displaying in terms of watts out (I
think it was a low number), but I confirmed the output at 165w using
two external wattmeters (first the Elecraft W1, which I did not
totally believe because it was maxed out, then my Bird 43 with 1000w
slug). I was connected to a Bird 125w dummy load, confirmed 50 ohm.
The cable was probably not the best, it was a 20 ft run of RG-58 I
think.
My kit used the red toroids, and I assume at L15 and L16 but would
have to check when I can look at the kit (when I get home). Also will
have to check the value of C31.
Don't know if this will help you or not . . but this is what I can
provide for now. Will check the rest when I get home this evening.
Thanks,
Mike
N4JX
----- Original Message -----
From: Don Wilhelm <
[hidden email]>
Date: Monday, June 11, 2007 8:57 am
Subject: Re: [Elecraft] Strange KPA100 behavior
To: Mike Geddes <
[hidden email]>
Cc: Elecraft <
[hidden email]>
> Mike,
>
> Is the K2 displaying 165 watts? Or is the K2 displaying 0.2 watts
> or
> lower while an external wattmeter is displaying 165 watts?
> What is your test setup that gives you a 7:1 SWR? If you are
> feeding a
> resistive 50 ohm dummy load with good coax, the wattmeter (either
> internal or external) should read 1:1 even with a KPA100 problem.
>
> Tell us more so we can help with your problem -
> Taking a very wild guess, you either have a non-functioning
> wattmeter in
> the KPA100, or the KPA100 wattmeter is not calibrated, or you have
> a
> parasitic oscillation in the KPA100.
>
> Since this is a new kit - do you have blue toroid cores at L16 and
> RFC1
> or do you have red toroids at L15 and L16? And tell us what the
> value
> of C31 is and whether you determined the value by looking at the
> capacitor (preferred) or whether you just looked at the parts
> list/schematic.
>
> We need the answers to all these questions before we can advise
> you further.
>
> 73,
> Don W3FPR
>
> Mike Geddes wrote:
> > Greetings. I recently finished my K2 KPA100 kit. It seemed to
> work okay
> > initially, then last night started to exhibit some strange
> behavior. It
> > would transmit correct power on tune under 11 watts (and show
> low SWR),
> > but on anything over 11 watts, on tune, it would transmit around
> 165
> > watts and show an SWR of around 7:1!! And giving High Current
> message
> > Is there anything I should start looking for initially?
> >
> > Any suggestions are appreciated.
> >
> > Thanks,
> > Mike
> > N4JX
>
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