Double discone

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123

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Any of you guys ever tried one of these? I have a diamond right now 40ft in the air. Mainly monitor mil air....

Thoughts or experiences ?
 

prcguy

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Save your money. I bought a Nevada Double Discone and a RS Discone works better over a wider frequency range.

Even the name is made up, its not a Double Discone, its a Bicone or Biconical but without the needed matching network at the feedpoint.

I have a couple of real Bicone antennas and they are rated for around a 3 to 1 or 3 to 1 frequency range compared to a Discone which is rated for about 8 to 1 frequency range if properly designed.

My Nevada POS has a good match around 2m but thats about it compared to any other scanner type Discones which have a useable match from around 100 to 800MHz.

For a real Bicone check out the Harris RF-9070 which is rated for about 90 to 470MHz with some slight degradation but in reality it seems to have some gain within its full spec 100 to 400MHz range. Unfortunately it costs a lot of money due to the engineering and complicated matching network in the hub. Here is a link to a spec sheet for the Harris, otherwise there are no good Bicone antennas for a cheap price except for imposters like the Nevada or the rare military surplus find like my Harris RF-7090.

http://rf.harris.com/media/RF-9070_tcm26-9211.pdf

And another thing, the Harris is about 5ft tall and 5ft wide and only covers 90 to 470Mhz at its maximum ratings. I have another military Bicone that covers 30 to 90MHz and its about 18ft tall and 6ft wide where the Nevada is maybe 4ft tall and 2ft wide. How do they get 25 to 1300MHz coverage from something that small? They lie, that's how!
prcguy
 
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2531

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cape cod
prcguy
to convert the Double Discone back to a Discone,
what size? solid disk should i use.
thanks
 

prcguy

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It looks very simple to make one and possibly two Discones from a Nevada Double cone thingee. I was considering the same thing but have enough Discones at the moment.

I remember the dimensions for a Discone is the skirt is an equilateral triangle with the length of one side slightly longer than 1/4 wavelength at the lowest frequency and the disc diameter is between .67 and .7 of the skirt length. Then the spacing between the disc and skirt will affect impedance and VSWR.

I would make the disc from aluminum sheet metal around .063 thick and hopefully the stud on top of the hub assy will space it right for a good match.
prcguy





prcguy
to convert the Double Discone back to a Discone,
what size? solid disk should i use.
thanks
 

zguy1243

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Apr 24, 2006
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Calhoun Georgia
Any of you guys ever tried one of these? I have a diamond right now 40ft in the air. Mainly monitor mil air....

Thoughts or experiences ?
Get you a Kreco discone. I know you wanted the VHF performance with the UHF too. (I guess why you stopped using the AT-197?) The Kreco has the great build quality like the AT-197 did but is a bit more broad banded. Kreco has a number of different models that really work well and built very nice. The price is acceptable too for hobby use.....
 

ridgescan

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I saw that DDiscone at HRO they want $150 for it-I still have a skirt from an old discone here I was thinking I could just bolt that to the top of my D130j lol and have the same thing.
 

prcguy

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Yes, you would have the same thing but I think it would be going backwards from a Discone.

BTW, there was a new KRECO 100-800MHz Discone missing the top hat radials on EBay recently. I got it for cheap and already received replacement parts from KRECO.
prcguy


I saw that DDiscone at HRO they want $150 for it-I still have a skirt from an old discone here I was thinking I could just bolt that to the top of my D130j lol and have the same thing.
 
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