[Elecraft] RE: KPA100 "negative resistance" -- more

[Clay T. Whitehead]

As you know, I had the same experience.  The not-so-cheapo halogen lamp on
the workbench caused a large part of the problem; turning it off greatly
reduced - but did not eliminate - the "negative resistance".

I concluded the same as you - some rectification of stray fields was causing
the phenomenon.  Based on advice from someone on the list, I just went ahead
building, and everything turned out fine in later stage tests.  Let us know
where you come out.

Tom
W6WW

-----Original Message-----
From: Ward Willats [mailto:ward@wardco.com] 
Sent: Monday, November 17, 2003 1:44 AM
To: tom@cwx.com
Subject: KPA100 "negative resistance" -- more

Well, turning my cheap-o swing arm incandescent desk lamp off ran the 
stray voltage way down.

In fact, turning it off made the measurements come out right -- and 
turning it back on made them go screwy again.

It doesn't seem photo-sensitive -- but sticking my hand in front of 
the bulb does change the field and drop the mystery voltage some.

So I guess it is "miracle rectification" -- I think your posts just 
saved me days of troubleshooting. I'll measure all this phenomena for 
the record and proceed, if it works I'll post my data points to the 
list too.

Thanks for helping me through the Twilight Zone,

-- Ward / KG6HAF