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Scanner Antennas

N5TWB

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Sand Springs OK
#2
Can anyone make a suggestion about a good outdoor Disc Cone antenna for my TRX-1 police scanner?
I just did a quick search on HRO and showed they carry 10 different ones with varying frequency coverages, with/without coax cable, size, # of elements, etc. One of those will likely work for you after you determine your desired frequency range, features, and budget. Just remember that a discone has no gain to help pull in marginal signals and its main advantage is a wide frequency range which allows it to serve as a "do-all" antenna when simply getting the antenna outside and higher serves your needs for receiving signals. If your area of interest is more specialized, i.e. an 800 MHz trunked system with simulcast sites, the discone may be your worst enemy.

For the HRO search, go to the main page: www.hamradio.com and use the search by category drop-down box on the left side of the page. One of the selections is "antenna discone."
 

TailGator911

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#4
I can suggest the Diamond D130NJ discone, as I have had great results with it. I have it on outside mast 25ft high on side of house and I put it thru 8-port Stridsberg multi-coupler and feed several scanners with it. I have a coax feed that I alternate with SDS100, TRX-1, and BC125AT and it works great.

JD
kf4anc
 
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#6
I was able to score a Diamond DJ-130N many years ago for free. I put it up as a temporary solution for a VHF transceiver at home.
I'm usually not much of a fan of consumer/hobby grade antennas, so I figured I'd replace it in a year or so with something better.

It's probably been up for 10 years. No issues, still works as well as the day I installed it. Hasn't lost any elements.

A couple of things if you are going to purchase one:
Get the N connector version. N connectors have a bit better performance at higher frequencies. Probably not a huge difference, you might not even be able to notice, but if you have the choice, get the N.

Mount it properly.

Waterproof the outdoor coaxial connections. Not a wrap of electrical tape, but proper waterproofing. That would be a layer of electrical tape overlapping 50%, wrapped from bottom to top. Put a layer of Coax Seal or similar moldable sealing tape over that. Then another layer of electrical tape, from bottom to top, overlapping 50%.

Keeping water out of the coaxial connection is key.
 

KC3MER

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#7
I can suggest the Diamond D130NJ discone, as I have had great results with it. I have it on outside mast 25ft high on side of house and I put it thru 8-port Stridsberg multi-coupler and feed several scanners with it. I have a coax feed that I alternate with SDS100, TRX-1, and BC125AT and it works great.

JD
kf4anc
I just bought the Diamond D-130NJ from Gigaparts about an hour ago. Do you mind telling me what coax you are using. I am going to purchase the coax with both ends N type and a jumper N type female to BNC male.
 

KC3MER

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#8
I was able to score a Diamond DJ-130N many years ago for free. I put it up as a temporary solution for a VHF transceiver at home.
I'm usually not much of a fan of consumer/hobby grade antennas, so I figured I'd replace it in a year or so with something better.

It's probably been up for 10 years. No issues, still works as well as the day I installed it. Hasn't lost any elements.

A couple of things if you are going to purchase one:
Get the N connector version. N connectors have a bit better performance at higher frequencies. Probably not a huge difference, you might not even be able to notice, but if you have the choice, get the N.

Mount it properly.

Waterproof the outdoor coaxial connections. Not a wrap of electrical tape, but proper waterproofing. That would be a layer of electrical tape overlapping 50%, wrapped from bottom to top. Put a layer of Coax Seal or similar moldable sealing tape over that. Then another layer of electrical tape, from bottom to top, overlapping 50%.

Keeping water out of the coaxial connection is key.
Thank you
 
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#9
I just bought the Diamond D-130NJ from Gigaparts about an hour ago. Do you mind telling me what coax you are using.
I'm using LMR-600. I had a bunch left over from a project at work. It's only about a 35 foot run from my antenna to the radio.

Depending on your cable run, you can get great results with something smaller and less expensive.
But, since discone antennas are 0dB gain, you don't want to use anything with too much loss, or too long a run. You want to make sure you are using coaxial cable with a low enough loss to get an appropriate amount of signal to your scanner.

I am going to purchase the coax with both ends N type and a jumper N type female to BNC male.
That's the way to do it. A short RG-58 jumper with a female N on one end and a BNC, or what ever matches your scanner, on the other end. That keeps the strain of the heavier coaxial cable off the radio's antenna jack.
 

KC3MER

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#11
I'm using LMR-600. I had a bunch left over from a project at work. It's only about a 35 foot run from my antenna to the radio.

Depending on your cable run, you can get great results with something smaller and less expensive.
But, since discone antennas are 0dB gain, you don't want to use anything with too much loss, or too long a run. You want to make sure you are using coaxial cable with a low enough loss to get an appropriate amount of signal to your scanner.



That's the way to do it. A short RG-58 jumper with a female N on one end and a BNC, or what ever matches your scanner, on the other end. That keeps the strain of the heavier coaxial cable off the radio's antenna jack.
 
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#16
I need about 50 feet of coax
Give this tool a try and consider the results. It's kind of hard to recommend the correct cable to use without knowing all your parameters.

Coax Calculator

As frequency goes up, so does cable loss.
As cable length goes up, so does cable loss.

So, if you are planning on doing a lot of 800MHz or higher listening, and you are on the fringes of coverage, you may need to consider higher grade cable than LMR-400 to get enough signal to your scanner to be useful.
On the other hand, if all your interests are in the lower frequencies, then a lower grade cable might be "good enough". RG-6, while it is 75Ω cable, can have pretty good numbers. It's cheap and readily available. Getting N connectors to fit it can be a bit of a challenge, though.

Comes down to your budget, ultimately. Good cable can be expensive. But, good cable is usually worth it. Installing coaxial cable can be labor intensive and in some cases, dangerous, so doing it right the first time can be a good investment.

If you are going to get pre-terminated cable, make sure your cable path will give you room to pass the connector. N connectors are not really that big, but in some installations it's easier to run unterminated cable.
Also, the larger cables can be pretty stiff. LMR-600, Heliax, etc. can be a bit of a pain to work with if you are trying to route it through walls or other tight spaces.
You may also want to consider getting the "N" female on the radio end. That makes it a bit easier to route, and easier to get jumpers down the road if you change antennas.

Also, since you have a ham call sign, consider whatever you do may at some point get used for transmitting.
 
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#17
Also, pay attention to the cable brand.

Beware of any company that tries to sell you "Same as LMR-400", or "Similar spec's to LMR-400", or "LMR-400 compatible", etc.
The Chinese have infiltrated the coaxial cable market online and will sell some pretty cheap coaxial cable with questionable quality. My comment above about installation time/cost should figure in. Go with the "real" stuff if you intend to keep it for a long time.
 

TailGator911

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#18
I just bought the Diamond D-130NJ from Gigaparts about an hour ago. Do you mind telling me what coax you are using. I am going to purchase the coax with both ends N type and a jumper N type female to BNC male.
RG6 and as Mmckenna said, waterproof connections.
 
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Stockholm, Sweden
#19
That would be a layer of electrical tape overlapping 50%, wrapped from bottom to top. Put a layer of Coax Seal or similar moldable sealing tape over that. Then another layer of electrical tape, from bottom to top, overlapping 50%.
That could be one way to do it but the professional antenna installers I've seen, and also how I do it, are to first put the rubber mould or vulcanising tape on first, to make it water tight, and the electrical tape on top of that to protect it from the enviroment and animals. Haven't really seen that first layer of electrical tape being applied, neither in real life or in instructions that comes with an antenna connector sealing kit or in videos.

/Ubbe
 
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Messages
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So Cal - Richardson, TX - Tewksbury, MA
#20
Andrew Heliax connectors, now under the Commscope name has always specified a layer of electrical tape first, then the sticky stuff, then a final layer of wide thick electrical tape. This is in most published instructions for Heliax connectors. If you don't put down a layer of electrical tape first you will have a terrible time getting the sticky stuff off if you ever have to remove the connector.

That could be one way to do it but the professional antenna installers I've seen, and also how I do it, are to first put the rubber mould or vulcanising tape on first, to make it water tight, and the electrical tape on top of that to protect it from the enviroment and animals. Haven't really seen that first layer of electrical tape being applied, neither in real life or in instructions that comes with an antenna connector sealing kit or in videos.

/Ubbe
 
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