Gary:
You following this thread? This is the second (NOT counting NN0B's)
problem which may be related to KPA100 parasitics.
Tom
__________
Hi Rob,
Your problem sound a bit different. What was happening on
quite a few earlier KPA100's was the diodes in the switching circuit were
providing enough capacitance to cause a tuned circuit with RFC3 and that
circuit would break into oscillation and modulate the carrier with a
spurious signal. The resulting signal then had nasty sidebands and I used
to get accused of "Splatter". It used to occur at powers above about 80w.
mainly. The fix was to dampen RFC3 with a 1k resistor as well as a resistor
change in the high voltage bias supply to make sure the HV supply didn't
drop too low on demand.
The changes are outlined in the "K2/100 Manual ( Appendix G) ERRATA" rev.
C-3, December 14, 2004. ( steps 1 and 3 ) which is obtainable off the
Elecraft Web site.
Hope this helps?
Cheers.......Ron ZL1TW
At 07:20 AM 4/24/2005 -0700, you wrote:
What are the symptoms of the oscillation? My KPA100 sometimes loses
connectivity with the K2 and the communications between them is lost. Only
fix is to power them both down. Don't know where to start looking for the
problem. RFI?
-rob N7QT
----- Original Message ----- From: "Ron ZL1TW" <[EMAIL PROTECTED]>
To: <elecraft@mailman.qth.net>
Sent: Sunday, April 24, 2005 4:15 AM
Subject: [Elecraft] Re: KPA100 question
Hi,
Just my 2c worth......in the days before the stray oscillation that
occurred in *some* KPA100's was found and a fix presented, I was advised
by Gary to try mounting my C83 on the *TOP* of the ends of the 1 and 3
"winding" of T2, and it is still there lying parallel with the PC board,
so having it slightly off vertical in the suggested position shouldn't
matter a fig I imagine.
.........................snip ........snip.............
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