It seems I did not make myself very clear in my A3 Antenna Problem
message, this morning. I've received a number of suggestions to
check the remote coax switch. Thanks to all for responding so
quickly. That's what this medium is all about. However, to preclude
further suggestions pointing fingers at the remote coax switch, let
me say this:
1. I ran checks on all antennas from the radio. All antennas except
the top A3 are performing nominally (<1.3:1 SWR on the bands and
in the band segments it should be low, and hearing well where they
are supposed to hear well and hearing less well where they are
supposed to hear less well.).
2. I ran checks on all antennas from the radio position with the
MFJ-259 and got similar results as in (1) above.
3. My remote coax switch is mounted on a wall in the attached
garage on the other end of the house from the radio room. I
disconnected all antenna feedlines, did MFJ-259 checks on each
for their respective bands and SWR readings were similar to those
read in (2) above.
4. I connected the radio feedline directly to the A3 feedline and
checked SWR (1.8:1 or a bit higher on 10-15-20m), directivity was
virtually nil (A KP2 on 20 was as strong pointing the A3 NW as SE,
and other stations achieved the same result).
5. I used the MFJ-259 from the radio position and got the same
SWR results as (4) above.
6. Finally, I put a dummy load on the radio feedline to the coax
switch. It checked 1.1:1 on all bands. I reconnected the radio
feedline to the remote coax switch and, with the dummy load
put on each position in sequence, got the same 1.1:1 reading
for each position. I even switched to a position without the
dummy load and did a low power open circuit test: extremely
high swr...as expected.
So, I think I have conclusively excluded the remote coax switch
as a problem area. That leaves only the top A3 feedline run from
the coax switch to the balun, the balun, and the A3, itself.
As soon as the weather breaks (it's been raining for a week now!
Southern Leopard Frogs are committing suicide in my swimming
pool!) and things dry out a bit, I'm going up the tower to check
things out up there.
If it's not the feedline or the balun, I'll probably just drop the A3
and check it out on the ground.
Besides, I have the 40m add-on kit for it and I need to put that on.
I was just going to remove the driven element, lower it to the ground
and put the add-on kit on it, then haul it back up and reattach it to
the boom. (anyone done it this way?). But, this lightning thing and
the rain has forced me to change my plans.
CQWW and SS are coming fast!!
73,
Dale Martin, KG5U
kg5u@hal-pc.org
http://www.hal-pc.org/~kg5u
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search
|