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Author Topic: Discone antenna choices? No low band needed.  (Read 7999 times)
N2NJO
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Posts: 140




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« on: September 09, 2011, 05:09:13 AM »

I'm looking for a Discone antenna covering staring around 100 to 130 MHz and up to as high as it can be designed and still perform properly. I know there is a approximately 8 to 1 ratio from the bottom frequency to the top with what I assume is a 'smudge factor' that might extend the coverage further. It also must have a N connector.

What I don't want is any of these dime a dozen, typical 'scanner' antennas under $100 or the found everywhere Diamond. On the other hand I don't need some military spec'd model for $500 either.

The only one I found is this;
http://www.krecoantennas.com/broadband.htm

There is also this, but it has that top low band element that I don't want;
http://www.apexradio.co.jp/713G-DA_e.html

Anyone have any suggestions?
« Last Edit: September 09, 2011, 05:19:05 AM by N2NJO » Logged
WB6BYU
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Posts: 13028




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« Reply #1 on: September 09, 2011, 08:50:34 AM »

The low band vertical whip generally has a standard 3/8-24 mobile antenna thread on the bottom.
Just unscrew it if you don't want it on your antenna.

While the antenna may have a low SWR over a 8 : 1 frequency range, the angle of radiation is often
non-optimum over at least the top half of the range.  Don't expect peak performance over more than
about a 3 : 1 range or so, but it may still be adequate for your needs.
« Last Edit: September 09, 2011, 08:53:01 AM by WB6BYU » Logged
N2NJO
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Posts: 140




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« Reply #2 on: September 10, 2011, 05:22:22 AM »

80 views and only one reply? No one used discones for wide band receiving??

I realize a discone is a compromise. I didn't know the pattern changes as frequency increases.
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K1CJS
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Posts: 5884




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« Reply #3 on: September 10, 2011, 07:10:34 AM »

Unfortunately, what you're going to find out there as far as discone antennas go are either mass produced, low cost antennas, or antennas that have been made of quality components--and at 'quality' prices.  There aren't many that are in between the two.  You're requirement for a N connector throws a further wrench into the works because a discone antenna is a unity gain antenna that isn't usually in need of such a quality, low loss connector.

I've had one of those mass produced Radio Shack discones up for many years for a scanner, and outside of the occasional bent cone elements, it has performed well. 

If you're insisting on the N connector because you're hesitant on removing the N connector from the end of your cable, simply get an adapter--PL-239 to N.  Other than that, you don't have very many other choices.

BTW, 'BYU is right--if you don't want the upper long element on your antenna, just leave it off.
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N2NJO
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Posts: 140




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« Reply #4 on: September 15, 2011, 09:15:10 AM »

The N connector is mandatory as I won't use outdated CB connectors again for VHF and above. The little bit ($$) you save isn't worth it AFAIC.

I just wanted to be sure I didn't miss some other antenna in my search.
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K1CJS
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« Reply #5 on: September 16, 2011, 12:03:38 PM »

The N connector is mandatory as I won't use outdated CB connectors again for VHF and above. The little bit ($$) you save isn't worth it AFAIC.

I just wanted to be sure I didn't miss some other antenna in my search.

I understand.  Just as long as you realize that you're limiting yourself to certain antennas--all of which are probably in the high cost area.  BTW, "outdated CB connectors?"  You do realize that the SO/PL 239 isn't a CB connector--outdated or otherwise.  It's an RF connector that dates back to WWII, and is good for over a kilowatt of power--well, today, the quality ones are.  It was used for radar connection applications and RF applications back when 6 meter and 2 meter radios were considered to be UHF type radios.  Generally speaking, the loss factor at 2 meters isn't high at all, and doesn't get to the point of being really noticeable even on the 1.25 meter band.  It's only when you go up into the 70 cm band that it may--may--start to cause problems with fringe area reception and transmission.

IOW, the requirement you want of using an N connector may well not be worth the importance you put on it--in practicality.  Cost considerations aside, you're limiting yourself to using a better connector where a better connector doesn't really do better than the standard quality connector would.  However, to each their own.  Good luck--and remember, have fun!
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KB9TMP
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« Reply #6 on: September 19, 2011, 02:40:36 PM »

You might want to give this one a look http://www.hamstick.com/d16.html The + version is only $54 has no "low band" element and has the N connector you're wanting. It's listed as a scanner antenna but is also listed for 2m 220 & 440 TX.

73 de KB9TMP
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KG4NEL
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Posts: 373




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« Reply #7 on: September 19, 2011, 02:56:22 PM »

http://www.rffun.com/catalog/scanants/1945.html ?

Not a discone, but wide BW w/ an N connector: http://www.rffun.com/catalog/scanants/1628.html
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N9LCD
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Posts: 166




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« Reply #8 on: September 21, 2011, 06:26:11 PM »

Go to www.mpantenna.com and look at their Super-M Ultra Mobile Antenna.  The mobile is a half-discone; they also have a discone version for fixed app's.

SPECS:

SCANNERS: 25 MHz - 6 GHz; Ham Radio: 144 MHz - 6 GHz; Two-way radio 120 MHz - 6 GHz.

200 Watts < 512 MHz; 100 Watts > 512 MHz.

19" high; 12" diameter; for NMO-style mounts.

I use three of them indoors on commercial-grade NMO-mounts with LMR-equiivalent coax and Type N connectors from Pasadena Networks.  They're great for monitoring up to 2 GHz -- even from a below-grade level shack.

Not the cheapest, but good!

N9LCD

 Smiley
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KI4SDY
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Posts: 1452




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« Reply #9 on: September 22, 2011, 08:43:06 AM »

I am using the Centerfire Discone Antenna at work. It is a great wide range receiving antenna and after tuning the radiator, I am getting 1.05/1 to 1.3/1 across the 2 meter band on transmit. I am going to add a specifically tuned ground rod or two and I think I can do even better on the SWR. It is rugged and well made. For $39.00, I would give it a try. I think you will be happy with the performance for the money spent. Government agencies are buying their antennas. Go to their site at Centerfire Antennas to order one!  Wink  
« Last Edit: September 27, 2011, 07:57:21 PM by KI4SDY » Logged
N0YXB
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Posts: 302




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« Reply #10 on: September 22, 2011, 11:05:06 AM »

I am using the Centerfire Discone Antenna at work. It is a great wide range receiving antenna and after tuning the radiator, I am getting .05/1 to 1.3/1 across the 2 meter band on transmit.

Perhaps you mean 1.05:1 to 1.3:1 SWR across the 2 meter band?   Of course this from the guy who says we don't peer review of technical articles posted on eHAM.  Smiley
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Vince
N2NJO
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Posts: 140




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« Reply #11 on: October 11, 2011, 09:13:21 AM »

I went with the Kreco 150AN discone. Not cheap, but neither is the quality. Huge difference between the weight of this and the flimsy 'scanner' antennas.
12 elements instead of the typical 8 and a much flatter response over what the two discones I had (a no name, locally made discone and another model of forgotten manufacture).
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K9KJM
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Posts: 2416




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« Reply #12 on: October 11, 2011, 10:57:14 PM »

Sounds to me like you are looking for something like the Icom AH8000 antenna:

http://www.universal-radio.com/catalog/scanants/1945.html

Those come with the type N connector.

Over the years I have worked with both them and the older AH7000 antennas, And unless you really NEED the wideband feature to listen to military oddball, etc frequencies, I consider these antennas overpriced for the very LOW performance they give.

All discone type antennas are low performance.   If you just want to listen to the normal stuff received on scanners, Those cheapo multi dipole antennas ARE a good deal, Even though they are pretty flimsy and tend to blow apart in high winds on tall towers. The multi dipole types do have lots more gain than the discone types.
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N2NJO
Member

Posts: 140




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« Reply #13 on: October 12, 2011, 03:41:31 AM »

The Kreco is the same price as the overpriced ICOM. Why would I buy the Icom???
8 vs 12 elements, Japan vs US made.

No contest. (I do want the wideband coverage)
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KQ6Q
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Posts: 965




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« Reply #14 on: October 13, 2011, 12:29:25 PM »

Unless you have a huge urge to spend more money, a vanilla Radio Shack discone and some good coax with PL-259's are all you really need. I have the RS discone 10 feet above my roof, clear show at the horizon in all directions, fed with RG-8 foam, and have excellent results, even on 1.2 Ghz fed with 1 watt from my T-81A HT. What kind of signals are you hoping to receive ?
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