[Elecraft] K2/100: PA Oscillation Problem: Help!

Sun May 25 07:17:01 2003

I had the same problem with my K2/100 PA and Gary sent me some pictures of a
grounding strap which cured my problem.  I will forward the email and
attachment to you directly.

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of [email protected]
Sent: Saturday, May 24, 2003 9:47 PM
To: [email protected]
Subject: [Elecraft] K2/100: PA Oscillation Problem: Help!

My newly constructed 100-watt PA has been going into oscillation!
Has anyone else had this problem??  This is a tough one! I've been trouble
shooting all day. Please review the following and let me know if you can
help.

1.  Occurs on 20, 15, 12 and 10 meters i.e. higher frequencies.
2.  Oscillation causes current surge (blows fuses) and has high amplitude
with varying frequency.
3.  This one is interesting! Occurs in SSB when talking/huming loudly for
several seconds.  Also sometimes occurs when the ATU is in tune. In other
words,
only modulated signals cause the oscillation to start.  Oddly enough works
well in CW (no oscillation) i.e. at least not manifestation of the problem.
4.  NO oscillation in when PA is off i.e. Power < 11 watts. Oscillation
occurs when power is between 11 and 100 watts. Seems to occur just as often
at 11
watts as at 100 watts.
5.  It's difficult to trouble shoot since oscillation occurs ONLY when PA is
in cabinet. If removed or � removed but still connected by cables, all works
fine!
6.  Often get "PA HOT" message even though PA is cool. (What's this one
about??)
7.  Once an "info 80" message was seen.

I'm hoping that someone dealt with a similar problem.
Thanks in advance & 73,
Jim WA2UMP K2/100:2679

--- StripMime Report -- processed MIME parts ---
multipart/alternative
  text/plain (text body -- kept)
  text/html
The reason this message is shown is because the post was in HTML
or had an attachment.  Attachments are not allowed.  To learn how
to post in Plain-Text go to: http://www.expita.com/nomime.html  ---
_______________________________________________
Elecraft mailing list: [email protected]
You must be a list member to post to the list.
Postings must be plain text (no HTML or attachments).
See: http://mailman.qth.net/mailman/listinfo/elecraft
Elecraft Web Page: http://www.elecraft.com