You mentioned in a past post (can't find it) about using two discone antennas together. Wondering if using my D220R with my full size discone would help in reception. Could you elaborate on your setup doing this?
Prcguy, chime in
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mitbr
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maybe this is the post.....
forums.radioreference.com
Tim
prcguy's mast mount filter/preamp/diplexer thingee
I've been wanting to provide my Icom R8600 with a really good wide band VHF/UHF antenna system and I finally have a plan coming together. The only way to get the bandwidth with no gaps is with Discones and one Discone can't possibly cover the 100Mhz to 3GHz capability of the radio, so I'm using...
That would probably be the thread. I've made a few changes in the last year and have a few more to do. Turns out I don't really need reception above about 950MHz so I replaced the small Discone with a commercial antenna with around 5dBi gain that covers the upper 700 to mid 900MHz range and its noticeably better than the little Discone but now I'm having some overload problems from a close by cell tower where some 700MHz carriers are coming in around -20dBm. That's really hot.
I have a higher level lower noise figure preamp going in and a new band pass filter from the mid 700 range to about 960MHz that will cut off the cell phone tower crap. I also found a commercial and small diplexer that will fit in the tower box so I'll replace my two filters and a T adapter with an actual diplexer. The end result should clean up my 800/900 reception and give lower loss path through for both antennas when the remote power is shut off and the relays in the box bypass the preamps and some other stuff for passive reception.
To answer the OPs question, a typical size scanner Discone like a D130 or Radio Shack will loose a lot of gain at the horizon due to the radiation pattern shifting upwards somewhere in the 400-500MHz range. I've measures about 10dB loss at 900MHz on one of these larger Discones where a small Discone got all that back. So if the D220R has a native size where its a real Discone in the 400Mhz on up range, that should spiffy up your 700/800/900 reception. If the Discone starts kicking in more around 200-300MHz then it may suffer from some upward pattern shift and loss of gain at the horizon on the upper bands.
I have a higher level lower noise figure preamp going in and a new band pass filter from the mid 700 range to about 960MHz that will cut off the cell phone tower crap. I also found a commercial and small diplexer that will fit in the tower box so I'll replace my two filters and a T adapter with an actual diplexer. The end result should clean up my 800/900 reception and give lower loss path through for both antennas when the remote power is shut off and the relays in the box bypass the preamps and some other stuff for passive reception.
To answer the OPs question, a typical size scanner Discone like a D130 or Radio Shack will loose a lot of gain at the horizon due to the radiation pattern shifting upwards somewhere in the 400-500MHz range. I've measures about 10dB loss at 900MHz on one of these larger Discones where a small Discone got all that back. So if the D220R has a native size where its a real Discone in the 400Mhz on up range, that should spiffy up your 700/800/900 reception. If the Discone starts kicking in more around 200-300MHz then it may suffer from some upward pattern shift and loss of gain at the horizon on the upper bands.
Thanks prcguy. Since finding out my current discone picks up as good or even a little better than my wire I was using for HF, was thinking maybe adding the little discone would help a little more. Since I am not to far from 4 simulcast sites, my SDS200 has no issues hearing P25 and analog PD transmissions. Hooking up to the discone does help more though. Since the D220R is collecting dust in my basement, figure to do something with it. Will keep an eye on on your thread that mitbr posted (thanks mitbr).
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