I am planning a 80 meter vertical. Since I also want to use it on 40 meters I
am proposing that it be 5/8 wave on 7.0 which would make it 5/16th wave on 3.5,
i.e. between 65 and 75 feet high.
I am thinking of building it of Rohn 25, except its my idea to use a 25AG top
section (it comes to a point with a 2.0 inch OD tubing) and then push up 10 to
15 feet of thinwall above that to make up the total height. The top set of
guys would be on the 25AG section, and I expect to use Phillystran.
I intend to use a radial system at ground level consisting 64 1/4 wave radials
(about 65 feet each) of perhaps 18 gauge wire. Elevated radials cannot be
used, trust me! No I don't have room for a 4 square!
Questions:
1. Grounded base (shunt feed) vs. Insulated base (series feed). I know the
insulated section is expensive, but so is the rest of my station so thats not
the issue. The issue is how will it work, will it be hard to match.
2. Am I making a mistake in suggesting a 25AG top section plus pipe above?
Will performance suffer versus using tower sections all the way up?
3. Assuming average ground conductivity, the charts show this area as 'Good',
will this be a good antenna on 40. On 80 I have no doubt that it will be
better than my inverted V at 70 feet center/50 feet at ends. My alternative on
40 would be a rotating shortened dipole at 72 feet, will the proposed vertical
will be at least as good as that.
Note: I don't care if I can be heard in the USA, my only interest is DX! I
want low angle!
Ron N5IN (ex K0UXQ) in Minnesota.
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