More Questions on the D130J(N)

I know there was a post about this a little while back. I am sort of rehashing the subject. I have been scanning now for a few months analog (BC355N). I am currently utilizing an old homemade J Pole mounted on the my rooftop with a 40 ft.run of old 75ohm coax straight to the receiver. I receive my local Fire, Police, Sherriff stations all really clear in the 151-159 MHZ range. I even get the county to my south in terms of the Sherriff's office, also in the 151-159 MHZ range very clear. My Air band frequencies 119 to 135 MHZ are what I would call adequate, at least for all towers within 250 miles. I notice I am very weak in the UHF frequencies 420 and higher. Also, I plan on upgrading to a Digital Scanner some time in 2016. I am located well above 750 ft. sea level on a hill so I have relative good antenna location as a whole.

Therefore my Question: I am seriously considering buying the Diamond D130N with a 75 ft. run of LMR400 50ohm cable in order to replace my J Pole set up as my primary Scanning Antenna. The new Diamond D130N would be mounted above my existing UHF/VHF TV Antenna, which is on the other side of my roof, about 5 feet higher than my j pole location (the reason for 75 ft of cable vs. existing 45 ft. to the J Pole. Given the fact that I am desiring improvement in the UHF band and higher and that I desire to have an improved signal reception when I buy my new digital scanner, in everyone's opinion, is this a good buy? Or, should I save my money for something else and just keep using the J Pole. Bottom line, I don't want to buy this Diamond and end up getting the same results as my J Pole that I spent maybe 25.00 making and is working okay for right now.

LMR-800 isn't a valid Times Microwave part number. Did you mean LMR-400, LMR-600 or LMR-900?

The discones are all around poor performers. What the excel at is covering a wide chunk of spectrum with passable results. Ideally you'd want an antenna with some gain on the frequencies you were interested in.

The VHF J-pole you have is going to work better for listening to VHF traffic than a discone will.
The discone will -probably- work better on the UHF, 700 and 800MHz bands than the J-pole will.
A dedicated VHF-UHF-800MHz antenna will outperform a discone.

If I could only install one antenna, I might look at a discone, but ideally I'd want something with a bit of gain. Your altitude puts you in a good spot, and the discone might work OK for most things, but you could probably do better.

Installing high grade coax is a good idea. Reducing feed line losses will help any antenna you install. Just pay close attention to proper weather sealing.

Yes sorry I meant LMR400 on the cable. I edited the post.

Since the discontinuation of the Antennacraft ST-2 there is a gap for those wanting a wide frequency coverage omnidirectional antenna for use as a base station scanner antenna. Reading these forums it would be easy to get the impression that the only alternative to the ST-2 is a discone. Discones are omnidirectional and cover a wide frequency range, but offer no gain. And as mmckenna has written here and elsewhere on RR "The discones are all around poor performers."
I do not own one (and have no connection with the manufacturer), but have seen many strong reviews for the following antenna: an OmniX by DPDProductions. It is very wide frequency coverage, omnidirectional, offers gain over a discone, and is a much lower visual profile than a discone (e.g. HOA-friendly) . To read the comments about it here on RR just Search and use OmniX as your search key. Here's the web page from the manufacturer:
DPD Productions - Scanner, Aviation, NOAA, Low-Band, 700 MHz Public Safety, Base & Mobile Radio Antennas for Commercial & Hobbyist Applications

Double discone - Long Communications

http://www.grcltd.net/product/wideband-bi-conical-dipole-antenna

http://www.reocities.com/n2uhc/bicone.html

A Discone is a great performing all around antenna, where the J-pole, Antennacraft ST-2 and other tuned to frequency are good to great performing antennas within a few narrow bands of frequencies. Where these other antennas do not have resonant elements, the Discone is much better, especially in the VHF and UHF air bands.

The typical scanner Discone works best from about the VHF air range to amaybe 500MHz then the pattern tilts upward, making 700-800MHz reception suffer. If you don't need those bands then a Discone is a great choice.

The "Double Discone" mentioned in a link is a big POS, I have one. Its a physical look alike to a Bicone or Biconical, but unlike the real thing the Double Discone has the wrong angles for its dimensions and no internal matching components.
prcguy

Nutes said:

Yes sorry I meant LMR400 on the cable. I edited the post.

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LMR-400 with a 75 foot run on 800MHz would be a good start.
You'll lose about half (2.831dB) of your signal on 854MHz with that cable. Not necessarily bad, but with a zero gain antenna you won't be helping much. That means you might want to consider some alternatives:
Higher gain antenna, mentioned above
Lower Loss coax, expensive, think 1/2" heliax, it'll only have about 1.5dB of loss. Not a huge difference, but it's "better" and will cost a bit more.
Add a low noise preamplifier near the antenna to boost the received signal and overcome some of the feed line loss (but it'll also amplify noise.

LMR-400 would be the minimum cable I'd use. If you have a lot you want to listen to in the 700MHz and 800MHz band, you might want to invest in higher quality cable. LMR-400 will work, though. If that's what your budget dictates, don't scrap the project.

Before going to hardline coax why not let the Discone do what it does best in the 100-500Mhz range and supplement it with a gain type 800 antenna and diplexer? There are lots of used 800 base antennas out there cheap in the 4 to 10dB gain range and a used 800 Yagi can be very inexpensive. A used Comet diplexer with a split around 550 and 800MHz shows up on Ebay often in the $50 range.

Both antennas would feed a single run of LMR400 via the diplexer and the end result would be better on 800 than going to big hardline and probably cheaper.
prcguy

mmckenna said:

LMR-400 with a 75 foot run on 800MHz would be a good start.
You'll lose about half (2.831dB) of your signal on 854MHz with that cable. Not necessarily bad, but with a zero gain antenna you won't be helping much. That means you might want to consider some alternatives:
Higher gain antenna, mentioned above
Lower Loss coax, expensive, think 1/2" heliax, it'll only have about 1.5dB of loss. Not a huge difference, but it's "better" and will cost a bit more.
Add a low noise preamplifier near the antenna to boost the received signal and overcome some of the feed line loss (but it'll also amplify noise.

LMR-400 would be the minimum cable I'd use. If you have a lot you want to listen to in the 700MHz and 800MHz band, you might want to invest in higher quality cable. LMR-400 will work, though. If that's what your budget dictates, don't scrap the project.

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prcguy said:

Before going to hardline coax why not let the Discone do what it does best in the 100-500Mhz range and supplement it with a gain type 800 antenna and diplexer? There are lots of used 800 base antennas out there cheap in the 4 to 10dB gain range and a used 800 Yagi can be very inexpensive. A used Comet diplexer with a split around 550 and 800MHz shows up on Ebay often in the $50 range.

Both antennas would feed a single run of LMR400 via the diplexer and the end result would be better on 800 than going to big hardline and probably cheaper.
prcguy

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If I buy an antenna to replace my J Pole, I could replace the J Pole Antenna location with the new antenna. If I do this, I will only need approximately 45 feet of cable to get to my scanner. Or....I can leave the J Pole and put up the new antenna (whatever it ends up being) on the other side of the roof. There, it will be a little higher and have clearer view of observation than the J Pole location, but it will require 75 feet of cable....therefore more loss.

Which would you do? Bottom line, higher placement and less obstacles but longer cable, or slightly lower, a little more obstacles but allot less cable run.

So after viewing over many, many conversations and threads about scanner antennas, I still don't get it.. my question is, which is the best all around outdoor scanner antenna with 800 mhz reception included.. rubber duckies and telescoping HH antennas excluded.. Yes, I'm tuned into coax quality and height.. LOL.. Your expert opinions are Vital..
Thanks in advance.. LOL
Doug
N7JGN

Best answer ive seen so far... "Before going to hardline coax why not let the Discone do what it does best in the 100-500Mhz range and supplement it with a gain type 800 antenna and diplexer? There are lots of used 800 base antennas out there cheap in the 4 to 10dB gain range and a used 800 Yagi can be very inexpensive. A used Comet diplexer with a split around 550 and 800MHz shows up on Ebay often in the $50 range.

Both antennas would feed a single run of LMR400 via the diplexer and the end result would be better on 800 than going to big hardline and probably cheaper.
prcguy"

prcguy said:

Before going to hardline coax why not let the Discone do what it does best in the 100-500Mhz range and supplement it with a gain type 800 antenna and diplexer? There are lots of used 800 base antennas out there cheap in the 4 to 10dB gain range and a used 800 Yagi can be very inexpensive. A used Comet diplexer with a split around 550 and 800MHz shows up on Ebay often in the $50 range.

Both antennas would feed a single run of LMR400 via the diplexer and the end result would be better on 800 than going to big hardline and probably cheaper.
prcguy

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I agree, that would be an ideal solution.

Here is a typical Ebay deal on the diplexer for combining a Discone and 800 antenna: Comet CF 413B Duplexer 1 3 460MHz 840 1 4GHz N Female PL 259 N Male New | eBay

Here is a used 800 omni base antenna that I would consider the minimum gain to get and this guy is accepting offers. I think its worth a $60 offer: Laird S8243B72SMM 824 896MHz 3DBD SMA Male Antenna Rack 5 | eBay I see similar and larger versions on Ebay occasionally and also at my local ham radio swap meet.
prcguy

prcguy said:

A Discone is a great performing all around antenna, where the J-pole, Antennacraft ST-2 and other tuned to frequency are good to great performing antennas within a few narrow bands of frequencies. Where these other antennas do not have resonant elements, the Discone is much better, especially in the VHF and UHF air bands.

The typical scanner Discone works best from about the VHF air range to amaybe 500MHz then the pattern tilts upward, making 700-800MHz reception suffer. If you don't need those bands then a Discone is a great choice.

The "Double Discone" mentioned in a link is a big POS, I have one. Its a physical look alike to a Bicone or Biconical, but unlike the real thing the Double Discone has the wrong angles for its dimensions and no internal matching components.
prcguy

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I have a D-130NJ and love it, I did not use LMR-400 though due to wanting a more flexible coax I Went wit Belden 9913F7.

Thanks guys for all the great input. Wow. Allot to think about. Man.... I am now really tempted with the Omni X Scanner Base Antenna. Looks like it "could" be a decent compromise in terms of achieving that 108 to 137 MHZ, 137-174 MHZ 800 MHZ combo. If anything, I guess if there was a group I had to leave out in terms of where I currently listen the most now, and where I want to listen in the future, it would be the 400MHZ range. This at least looks like a good compromise. Found former posts on this forum where people on here were really pleased with this antenna. However, it is a few bucks more than the Diamond D130N Discone, which I have the cash to go and pick up over the counter right now.

The cable decision is almost the harder decision. A 75 foot run is going to have to be the route if I want to put my Antenna in the best spot on my roof for height and clear sight. I would have two gradual turns and one sharp 90 turn. Maybe another reason I am leaning towards the Omni X, for the simple reason that it looks like there is some gain there that would at least make up for the 75 of cable run with LMR400.

I'm a little confused by what you wrote ("I guess if there was a group I had to leave out in terms of where I currently listen the most now, and where I want to listen in the future, it would be the 400MHZ range.")
The OmniX covers 118-137, 148-175 & 225-900 MHz. Unless I'm completely confused, "225-900 mHz" does INCLUDE the 400 mHz range you're looking for. What makes it necessary to "leave out" the 400 mHz range?
Regarding where to put the antenna: Do you have a handheld scanner? Take it up on the roof to both locations and check your favorite frequencies. Pick the spot where the majority of them have the best strength.... and then mount your antenna there.

Looking at the Omni-X design, it can't possibly provide continuous coverage like a Discone can. It probably works well at a few frequencies but who knows if it has lobes that point up in the air or ?? at some frequencies. A Discone is predictable with known performance.
prcguy

popnokick said:

I'm a little confused by what you wrote ("I guess if there was a group I had to leave out in terms of where I currently listen the most now, and where I want to listen in the future, it would be the 400MHZ range.")
The OmniX covers 118-137, 148-175 & 225-900 MHz. Unless I'm completely confused, "225-900 mHz" does INCLUDE the 400 mHz range you're looking for. What makes it necessary to "leave out" the 400 mHz range?
Regarding where to put the antenna: Do you have a handheld scanner? Take it up on the roof to both locations and check your favorite frequencies. Pick the spot where the majority of them have the best strength.... and then mount your antenna there.

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I'm not impressed by two positive reviews, if it were that good you would literally have to wade through all the positive reviews on the Internet. I'm sure the Omni-X is a well though out and good quality antenna, and congratulations to Dave at DPD for marketing a successful antenna, but I'm also a little familiar with antennas and understand what they can and can't do. On some frequencies it will outperform a Discone but there are places where a Discone will make it look bad too.

One thing about a Discone is it has very consistent pattern and gain across more frequency range than anything but the most exotic and expensive military types. Its a standard by which others are measured and many measure better here and there, but not everywhere.

I would like to get my hands on an Omni-X someday and run some range tests but that would be behind testing and comparing a bunch of popular mobile scanner antennas when my spectrum analyzer gets replaced soon.
prcguy

NDRADIONUT said:

http://forums.radioreference.com/sc...034-dpd-omnix-multi-band-scanner-antenna.html

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