[Lowfer] A bit of a problem with trimmer caps

[WE0H]

No problem.

On your thoughts about the sagging current during wet conditions, well we
both know that I still don't have the data you asked for last summer, but I
can verify that my current also drops a bit during wet conditions. Is some
if it the cap being lossy, don't know, but it will drop anyhow cap loss or
not. I finally got tired of having connections corroding up so I took a huge
gob of Vaseline to each terminal and disassembled each one and goobed the
heck out of them and then wrapped each one that is outside the tuner box
with the self fusing high voltage tape. Again, the air variable has LPS-1 on
its brushes so I doubt there is much of a wet condition problem there. The
current did go up the first time I sprayed the brushes and spun the cap
around a couple of turns to clean them up.

So I believe your cap will increase in value being submerged in oil; it will
also have a higher voltage and current rating. Do you think a new spotlessly
clean cap submerged in oil would have lower losses than a dry new cap???

How about an inductor; would the inductor maintain it's dry value Q if
submerged in oil??? Would it still be subject to outside influences as far
as lowering its Q say if it was moved near some lossy object like a human
body or would it not be influenced so much???

Mike>WE0H
http://www.we0h.us/lf

-----Original Message-----
From: lowfer-admin@mailman.qth.net [mailto:lowfer-admin@mailman.qth.net]
On Behalf Of The Loopster Bill Ashlock
Sent: Wednesday, February 05, 2003 9:34 PM
To: lowfer@mailman.qth.net
Subject: RE: [Lowfer] A bit of a problem with trimmer caps

Hi Mike,

>How about mounting the trimmer cap in a sealed enclosure filled with
>vegetable oil???

Like that idea! It might work just to soak the cap with the oil and figure
enough of it will remain in contact with the plates to prevent the oxide
from forming.

Here's an update: After giving the cap about 15 hours of a dry environment
inside the house, and then tightening and loosening the set screw a few
times while tapping on the case, I re-installed the final with the solid
state relay connected. The current is back up to what it originally was, so
this gives the solid state relay a clean bill of health but sure points the
finger at the trimmer. Now I'm beginning to wonder how much of the sagging
current on the big loop with damp conditions relates to the trimmer and not
to the wet ground under the loop. Grrrrrrrrrrrrrrrr!

Why don't I just fill the whole enclosure with oil? It's only 8 cu inches in
size. The trimmer adjustment is on the top so that would not be an obstacle.

Thanks Mike.

Bill