Hi Jim,
Most fitting that description that I have personally seen were 5/8 wave
11 meter antennas, or 0.64 wave which was common. I have never cut one
open nor tried to repurpose it to another band, but I suspect there is a
matching coil or network in that base insulator. If so this may cause
you problems trying to use it on other frequencies as a 1/4 wave (or 5/8
wave for that matter, with the possible exception of 10 or 12 meters. I
have one of those that I just threw into a load of scrap to be disposed
of. I know it was either 5/8 wave or 0.64 wave (but am not sure which)
because I was given the whole thing as an addition to my aluminum tubing
stash. If you want, I can see if it is retrievable (not buried too far
down in the load) and attempt to cut it open to see what is inside.
Paul N1BUG
On 8/8/22 01:26, Jim Pruitt wrote:
About 4 years ago I picked up 2 bottom sections of what I think were 11
meter ground planes. The section looks like the bottom section for a
HyGain 18AVQ vertical or similar. The only difference is the mounting
flange has a plate that holds what looks like about ½" diameter ground
radials. The issue I am having is that I used that mounting section to
make a 20 meter vertical. Easy enough, right? WRONG. I used mating
tubes to make the ¼ wave 20 meter vertical but it resonated at...ready
for this.... 39mhz! Then I grabbed the second one and used it. Now it
resonates at 13.5mhz but shortening the vertical does not bring the
frequency up. I am wondering if perhaps someone (CBer maybe) ran way
too much power through them and broke down the dialectic of the plastic
(or whatever that is) insulator that isolates the vertical from the
mounting bracket and ground. That is the only explanation I can come up
with as to why it is so far off.
Does anyone have any suggestions as to how to fix the problem?
Thank you.
Jim Pruitt
WA7DUY
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