Rodger
It seems a bit short electrically but with all that top loading you
should be able to radiate with a good ground radial system. Just
measure the impedance of the slant wire and design a match for that
value, I presume the "mast" is grounded at the base well. If you want
to make things easier you may wish to try a three of four wire cage
around the mast and connect it to the rotor cage and feed the cage at
the found level. Don't look for dips just look for a good match.
Herb Schoenbohm, KV4FZ
On 8/7/2015 10:54 AM, rodger bryce wrote:
Gentlemen, I have the following which I would like to turn into a topband
antenna if possible. My mast is approximately 40 feet high and there is rotor
cage with a 10 foot stub mast, on the stubmast I have an 8 el.log periodic and
above that a rotary dipole for 30/40m.
I attached a drop wire at approx. 38 feet high, I grounded this wire and tried to grid dip the wire plus mast, all as per ON4UN's book "USING THE BEAM TOWER AS A LOW BAND VERTICAL" the results were zilch, nadda nothing at all, no dip anywhere on any band. I used the MFJ 259B with the GDO accessory.
1. Am I doing this all wrong......highly possible.!!
2. Is the mast not high enough to be used for top band.?
I am totally out of my depth here.........so any guidance would be much appreciated.
Many thanks, Rodger/GM3JOB
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