Is this a problem only on 30M?
-rob N7QT
----- Original Message -----
From: "Ken K3IU" <[EMAIL PROTECTED]>
To: "'Gottlieb, Jonathan'" <[EMAIL PROTECTED]>; <elecraft@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 <[EMAIL PROTECTED]> so
that
they are aware that there is another builder with this problem.
73,
Ken K3IU
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Gottlieb, Jonathan
Sent: Sunday, June 12, 2005 12:12 PM
To: elecraft@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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