[TowerTalk] ground plane problem help needed

[N1BUG]

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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