Bill,

Is there another antenna on the tower near the beam or close by? If you have some type of wire antenna hanging on the tower maybe temporarily lower it to see it the SWR changes. That SWR change sounds pretty drastic. 

Jeff




Sent from my Verizon, Samsung Galaxy smartphone


-------- Original message --------
From: Bill Coleman <aa4lr@arrl.net>
Date: 12/4/20 1:37 PM (GMT-05:00)
To: South East Contest Club list <secc@contesting.com>
Subject: [SECC] Happenings at AA4LR - Good news and Bad news

Good news first. I scrambled up the tower this morning and re-installed my Cushcraft A3S/A743 before the rains came. (Indeed, that was hours ago and I’m still waiting on the rain) I wanted to get it off the ground before something happened to it after rebuilding.

Now, the Bad news. While the A3S/A743 is nicely resonant at four different frequencies, ALL of those frequencies are consistently BELOW the band:

40m - 6.9 (1:1), 6.975 (2:1)
20m - 13.16 (1.1:1), 13.29 (2:1)
15m - 20.45 (1.2:1), 20.66 (2:1)
10m - 27.73 (1.2:1), 28.57 (2:1)

I’ve gone over my measurements of the old antenna, plus the new measurements after re-assembly — they are not terribly different. Unless something went out of whack when I was putting up the antenna.

I took a spot measurement with the antenna standing up off the ground, and the resonances were all in-band. I expected them to go lower when I raised the antenna, but not buy several hundred kHz.

All the traps, however, are different. The TA (10m), TB & TC (15m) traps are from another A3S I had. The TK (20m) traps are brand spanking new.

Contemplating what I can do next, other than taking the antenna down again.


Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901

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