Diamond 3000N mounting question

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900mhz

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Antenna was fed with Andrew 1 5/8 inch heliax up at a commercial/public safety site. The radio equipment was inside a climate controlled building at the base of the tower with a backup generator.
 

prcguy

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For the typical scanner Discone rated for about 100 to 800MHz, the pattern starts to shift upward in the 400-500MHz range and by 800MHz the antenna is pointing more to the moon than the horizon. I might be exaggerating a little on the moon thing but I've measured them about 10dB down at the horizon at 800-900MHz compared to 500MHz or lower.

I think its best to use a Discone where it works best in the 118-512Mhz range then diplex in a gain type antenna for 700-800 or higher to supplement it. At my location I use a commercial/military Discone for 118-512MHz then a tiny Discone rated about 400Mhz to over 3GHz for higher stuff and combine them with a diplexer and some filters, amps, etc.

What kind of problems above 800?
 

vagrant

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So the 3000N marketing up to 3000 Mhz recieve is BS?
No, the claim is true. What you are overlooking in his post is the lobe/directivity of the antenna as the frequencies increase above 500 MHz. Most transmissions are terrestrial, so an antenna that has a receive directivity toward the horizon is preferred. He then notes he uses a different discone that is sized/tuned to perform better at the higher frequencies and brings both signals into his receiver using a diplexer, and plenty of filters, etc. etc. Prcguy posted a thread about that setup.
 
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