D130NJ Diamond Super Discone Antenna

llwade

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I have always used a different antenna for each band I wanted to Monitor. But, Discone Antannas, continue to temp me. Can anyone compare the reception of a Discone Antenna to an antenna tuned to a specefic band. Right now 90%, of what I listen to is in the 800 range and I have an antenna for that.
I am thinking about installing the discone antenna, to monitor air, marine, and rail bands. Thank you for your time
 

prcguy

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The D130 is not a good choice for 700/800/900 reception. For about 118 to 515MHz it’s fine. You can get a good 800 antenna and diplex it with the Discone for pretty good all band reception.

I did this recently and am very happy with the results. Here is some info on how I did it.

 

llwade

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PRCGUY: appreciate the response.
I am using a BS800 Panorama Antenna with a 4 port multicoupler (800-890 Mhz) to cover Illinois's Starcom 21 net.
Most of what I listen to is between 851-857 Mhz. I have 4 scanners dedicated for the 800 Mhz bands.
So 800 Mhz is already covered.

I wanted a separate antenna to cover everything else. That is why the Discone Antenna was so inviting.
I just didn't know if it would get the job done and satisfy my antenna VOID.
From what you said, it would be just fine for air, marine, and rail bands. Anymore, it seems like every day, another department encrypts their transmissions. This antenna will let me shop around for whats left. 73's your way. Have a good day.
 

bearcatrp

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I am currently using that antenna. Am not having any problems scanning in the 800 Mhz range. Am recording PD 50 miles away. My SDS200 is set for 1 mile. If I max out my range, can pick up wisconsin without issues. They are an hour and a half away from me. My discone is at about 30 feet high.
 

prcguy

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I am currently using that antenna. Am not having any problems scanning in the 800 Mhz range. Am recording PD 50 miles away. My SDS200 is set for 1 mile. If I max out my range, can pick up wisconsin without issues. They are an hour and a half away from me. My discone is at about 30 feet high.
Ive measured a D130 type Discone in the 800 band then swapped it for a roughly 300MHz to 2400MHz Discone and that was right at 10dB better, same mast, same coax. The problem is a Discone radiation pattern tilts upward about halfway through its native 8:1 frequency range and one that works around 100-120MHz on the lower end will be pointing up in the sky at 800MHz loosing a lot of gain at the horizon.
 

BC_Scan

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air, marine, and rail bands.
i personally think that the discone for rx is best bang for buck , up as high as possible with better than RG6 coax is best bet , they are in use everywhere and pickup in all directions that's why I like them
 

bearcatrp

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Since you say they point up at 800 Mhz, ever try pointing it a certain direction just to see how it did? Am not able to do this with my big discone but maybe could try it with the D220R I have.
 

vagrant

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The small Diamond D220R may be friendlier toward 800 MHz at the horizon than the larger sized D130NJ discone. I have not tested, but the smaller size...

@bearcatrp - Whenever I use the word "discone", I am definitely not referring to that smaller sized D220R even if it is a discone. If you have a NanoVNA, or the like, perhaps sweep that D220R from 118-200, 225-400, 400-700, 700-900 MHz. Those sweeps could then be compared with the larger Diamond discone. While it will not identify the lobes towards the horizon, it will at least provide some numbers to compare on those ranges.
 

Ubbe

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Most of the signal are taken up almost directly under a normal sized discone at 900MHz.

]
Sirio-SD2000.jpg


/Ubbe
 

bearcatrp

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I don’t have a nanoVNA. Should get one. Where is a good place to get one? When I get one, I’ll be back to ask for guidance on doing this. Never done this before. Definitely want to try out the D220R pointing toward a tower.
 

merlin

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I think my discone would compare to the D130 dimentionally. No clue who manufactured it, it came new at an auction.
Mounted 7 foot above a 2 story flat roof. Fed with 65 foot LMR600D coax.
The reception I get under 20 miles is too hot for my Bearcat and need 10 Db of attenuation. 800 to 900 MHZ I get good signals 60 miles away
from a 100 watt station at 6300 foot elevation. close to line of sight.
I had no way to measure the horizontal lobes at @ f/x However I did sweep this antenna and its broadband reasonance starts at 105 MHZ and very flat up to 800 MHz then a slow roll off up to 1000MHz. From 110 to 920 MHZ the SWR is less than 2.0:1 and insertion loss less than 2.0 Db.
I can only guess the gain at 140 and 450 is low, less than 2 Db. Less going higher in frequency.
SO, These antennas can't match performance of a single band or gain antenna, but their banwidth makes up for the difference.
Very well suited for receiving providing you get them high, like above utility poles/lines.
Can you transmit ? YEP, you cetainly can, likely up to 1000 watts.
ATM, it serves my XG-100M with very good results.
 

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Ubbe

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Normal sized discones operates the best at 100MHz in the broadcast band, something you don't want. Always use a FM trap filter with a discone. It is the sum of all radiosignals that overloads a receiver, so getting rid of the major ones in the broadcast range could help a lot.

The small DR220 are ideal for receiving frequencies from 400Mhz and upwards. To be able to recieve lower frequencies it has to use a top whip and work as a GP antenna, with a limited bandwidth like all vertical whips. You can do the same with a cheap (Tram) normal size discone by cutting all its elements down to half size, making it a 200-1000MHz discone.

/Ubbe
 

vannossc

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I have the DPD Omni-X and D130NJ on my roof, 40 ft of LMR-400 down to my shack, into an Alpha-Delta N switch, and ultimately connected to a Uniden SDS200. I regularly switch between the two antennas to see if I get better reception on one vs. the other. No scientific tests yet (this weekend I will have time to sweep both with Rig Expert 500 analyzer).

My anecdotal observations are as follows:

700-800 MHz essentially the same, leans OmniX
160-163 MHz DJ130NJ is almost -> deaf<- on these freqs
108 - 137 MHz Omni X def better, D130 works but weaker

Have not scanned lower but again, I'll sweep these from 27 to 500 MHz this weekend and post the results. Can't scan higher - anaylzer limit.
 

Ubbe

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Please use another receiver for the test. There's too many issues in a SDS scanner, automatic RF gain, overload, interference from other frequencies and so on. But you will see what antenna that works best for a SDS200 at your specific location, that might be the result of that the antenna receives less and then doesn't kick in the automatic gain or doesn't overload the scanner. It's similar to trying to receive simulcast with a non-simulcast capable receiver, you have to reduce the signal to make it possible to be received by a non optimal receiver.

/Ubbe
 

bearcatrp

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I had the mil omni. Worked as advertised, about the same as my discone on P25. But since it doesn't go above 1Ghz, I sold it. With my R8600, I like to scan above 1Ghz just to see if I can hear anything.
 

vannossc

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Here's that SWR scan finally. Omni X (non-mil) is green, Diamond D130JN is red. 0 - 500 mHz.
 

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