Dave wrote:
what brand/model? the 40-2cd has a known problem with the loading coil
connections becoming intermittant that gives symptoms just like that. other
loading coils, baluns, or matching section connections may do the same thing
on other models.

"Bob Dixon" wrote in message
...
My 40M beam works only intermittently. Typically under normal
conditions, the received signals are weak and the SWR is very high.
If I rotate the antenna, it "comes alive" in some directions and works
fine for a while, then dies again. In all cases, if I transmit into it
with a KW is comes alive and works fine for a while (few minutes) and
then dies again. A single dit will fix it. 100W does not do it.

I replaced the coax which runs around the rotator and it made no
difference. I just recently learned that a local friend also has an
intermittent antenna which can be restored by transmitting a KW into it.

Is this a common problem? is there a generic solution? Any hints
would be appreciated. Note that it is not too easy when up on the tower
to jiggle things while someone on the ground tries to watch the SWR and
shout back and forth. We tried that when we replaced the coax.


This antenna is probably going to have to come down for a look-see. I
would suspect something very near the area closest to the mast, but
those coils are a suspect too.

Running high power into the antenna might fix it, or might burn a coil
or other part up. I guess the rationale was to heat up an intermittent
connection, and "weld" it back together. Hoo boy, I'd pass on that.

Setting the antenna down will allow you to do some maintenance on the
whole thing. If you have one intermittent, problems can show up in other
places too, so its time to bite the bullet. Certainly not pleasant with
a 40 meter beam.

- 73 de Mike N3LI -