[Towertalk] Cushcraft X9 .. Bad trap?

[Dave Hough, W7GK]

Yes, that was a problem with those antennas. The first ones produced had 1 part number for a trap and the later ones had another part no. for the same trap.


----- Original Message ----- 
From: "Tony Wanschura" <tonyjw@mindspring.com>
To: <towertalk@contesting.com>
Sent: 19 November, 2002 09 29
Subject: [Towertalk] Cushcraft X9 .. Bad trap?


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




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