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Screw-driver Antenna Problem

Oct 25th 2011, 01:33

WE9U

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I have an older model factory-built(unknown mfgr) screwdriver antenna, that at one time would tune all H-F bands. I recently brought it out of storage, cleaned it, and replaced the finger-stock, and it now only tunes on 40M and up. No 75-80M at less than 3:1 SWR.
This model is built with 2" copper tube and has a balun inside between the SO-239 conn. and the antenna tube.
Any suggestions to get this to tune on 75-80M would be greatly appreciated.
Oct 29th 2011, 17:23

K0BG

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
It might not be "factory"made, as I don't recall anyone using copper for the mast portion. The balun you commented on, probably isn't a balun, but an unun. Even that isn't needed really, as a small shunt coil is typically adequate. Properly adjusted, the antenna will cover 80-10 with a reasonable SWR (<1.5:1).

Did you mean to say, it will tune 75, but the SWR is high??

Alan KØBG
www.k0bg.com
Nov 13th 2011, 02:38

WE9U

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
To Alan, thanks for your input, but I did get the problem solved.
And yes it would tune 75M, but the swr was 3:1 or higher.
Thank-you, again.

Bob KA9LLU

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