Discone antenna poor UHF

n1wof

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Apr 5, 2005
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15
Location
Shirley MA
I just put up a Diamond discone antenna. It hasn't been used in about 10 years, but it was indoors all that time in storage. Before it went up I checked the continuity from the vertical element to the center pin on coax. It seemed good. My issue is the UHF reception. Its absolutely horrible. The next town over is on 471.xxxx and is almost impossible to hear. As bad as UHF is VHF is amazing. When I checked continuity on the rest of the antenna everything was good to the shield of the coax. The only part that showed continuity to the center was the vertical element. Does this sound normal?
Here's what it looks like now....
antenna.jpg
 

cmdrwill

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Mar 30, 2005
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3,712
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So Cali
Some have said the bean pole, verticle element,on top, could cause the problem. That is for CB ect and tends to mess up UHF.
The horizontal elements should have continuity to the center of the coax. As would the "top element".

IIRC the top element unscrews and a nut replaces it holding the horizontal elements.
 

Ubbe

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Sep 8, 2006
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Stockholm, Sweden
If the horisontal elements have no connection to the top rod, and the coax center lead, it will only operate as a VHF GP antenna and not a wide frequency range discone.

Isn't it the same metal piece where you screw the top rod into and all the horisontal elements? Then you have to unscrew the horisontal elements and spray some anti corrosion lube or something into the threads. Measure resistance from the open threads to the top rod.

The top rod uses a loading coil at the bottom that will act as some sort of low pass filter that should make the top rod interfere less at higher frequencies.

/Ubbe
 
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