Immediately after putting up my Cushcraft X9 (with 40 meter add-on) =
about 3 years ago, I noted that the SWR on 15 and 20 meters was not as =
it should be. 10 meters was pretty much okay, but 15 and 20 were way out =
of range. On 15, SWR ranged from 2:1 at the bottom of the band to 5:1 at =
the top. On 20, the range was 3:1 at the bottom of the band and 2:1 at =
the top. A Minnesota winter was closing in, I operate almost entirely =
CW, and my rig's autotuner could deal with it. So I let the problem go =
until the following spring.
Working on the assumption that I must have made a mistake in element =
dimensions, I took down the antenna and re-measured every dimension =
twice, finding a couple of 1/8 inch errors here and there. I put the =
antenna back up and, of course, nothing had changed. Discouraged, I =
walked away from the problem for nearly a year.
This summer, I took the antenna down again, re-checked all measurements, =
removed the 40-meter element, and put the antenna back up. No =
improvement. All of this was a lot of work, since I have a guyed tower, =
with wire antennas hanging from it, and a 6-meter beam stacked above. I =
removed the wire antennas and the 6-meter beam. Still no improvement.
I replaced the coax. No change.
I am certain that all of the antenna dimensions are okay. The tower is =
50 feet tall, with nothing around it that might cause an SWR problem. =
This leaves the traps as the cause of the problem. I suspect an outer =
(15/20 meter) trap on the first director.
My questions are:
Does the behavior described above suggest a trap problem?
Has anyone else had a similar problem with the X7 or X9?
Thanks,
Tony
KM0O
--- StripMime Report -- processed MIME parts ---
multipart/alternative
text/plain (text body -- kept)
text/html
---
|