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Author Topic: Amateur Grade Antennas for Repeater Service  (Read 74437 times)
WB6ARE
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Posts: 2




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« Reply #15 on: July 05, 2015, 02:16:36 PM »

You can make a dual band commercial grade antenna by placing DB420 elements and harness on a DB224 mast.   I recommend the Telewave Crossband Couplers for at single feed: http://www.telewave.com/products/couplers/couplers.html.

This combo works great, providing 9 DB+ Omni on each band.  This antenna will outperform the rice sticks and definitely will out last them.  We have several up at 200-500 feet for six years with no issue.

Bruce wb6are 73
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K1ZJH
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Posts: 3573




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« Reply #16 on: July 06, 2015, 10:08:33 AM »

You can make a dual band commercial grade antenna by placing DB420 elements and harness on a DB224 mast.   I recommend the Telewave Crossband Couplers for at single feed: http://www.telewave.com/products/couplers/couplers.html.

This combo works great, providing 9 DB+ Omni on each band.  This antenna will outperform the rice sticks and definitely will out last them.  We have several up at 200-500 feet for six years with no issue.

Bruce wb6are 73


Good suggestion. Best of both worlds.

Pete
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N0GW
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Posts: 38




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« Reply #17 on: July 12, 2015, 07:18:32 AM »

Our club has three repeater installations.  Two of them are on 160 foot water towers that experience high winds.  The third is mid-way up a 1000 foot FM broadcast tower.  Amateur grade antennas would fail in only about three or four weeks.  The wind vortex vibration destroyed both the aluminum tube ones (Cushcraft) and the ones with fiberglass radomes (various manufacturers).

The antennas we have now have been up for several years with no problem.  The two on water towers are Antenex:

  http://www.ameradio.com/product/9308/description.html

The Antenex antennas feel like they are filled with something solid making them much heavier and stiffer than the amateur grade antennas.

The antenna on the FM tower is a DB224.

Gary - N0GW
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N0GW
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Posts: 38




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« Reply #18 on: July 12, 2015, 07:24:53 AM »

Oops, wrong model that Antenex antenna.  There are various frequency ranges available, including UHF.  Here is the page to select the correct one:

http://www.ameradio.com/brands/12-96-1/products.html

Gary - N0GW
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WB3AYW
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Posts: 53




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« Reply #19 on: July 18, 2015, 06:21:50 PM »

look up wb3ayw collinear antenna and build for 2 meters, it will work on 440 also.

Leonard Shick  wb3ayw
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K1ZJH
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Posts: 3573




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« Reply #20 on: July 19, 2015, 10:56:09 AM »

Spectral still makes the Isopole if you want to go with a two antenna solution? Very robust antenna! I have one here that is 20 years or older. Good antennas for a hostile enviroment.

www.isopole.com


We ran real-world comparison between the Isopole, CushCraft Ringo, and a commercial 5.8 dB Fiberglas stick on the 147.000 MHz repeater on Soapstone Mt, in Somers, CT many years ago.  The Isopole was close to a commercial fiberglass colinear,  the CC Ringo was blown out of the water.  The Isopole has proper coaxial feedline decoupling, and delivers real gain to the horizon.  Not in the same league as as Stationmaster, but a good sub.  At worst, maybe -2 dB down, which is about right.

Pete
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AF6D
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« Reply #21 on: July 20, 2015, 05:37:49 PM »

I thought of creating a new thread and decided against it. I just got an email from our new site vendor that is concerned that our LARGE 20 foot commercial antenna is too big and needs to be mounted at ground level making room for commercial customers paying double. This saddened me very much to see once again how it is. Our antenna is a DB224e and side-mounted offers 9dBd of gain. We have one at our back-up site at 85 feet coming down. Our main site has a an omni-directional Commander Tech 5.25dBd gain Station Master clone made "by RFS" that is worlds apart from the DB224. It does not compare favorably. I mentioned that we have a DB222 2-element dipole and I was urged to use it instead, that we not not see the difference between 6dB and 9dB at a repeater site? Really? That has not been our experience already. But what is the truth? It actually won't work - wrong frequency range. It really troubles me to be told directly that a guy is losing money by renting to me when he has 10 towers. Sure, they have value no doubt. I remain grateful still and I suppose I am more confused by being told that I wouldn't see a difference in performance between an 8 foot DB222 and a 23 foot DB224. It has always been my understanding that gain is derived from length. A 6dB gain mobile antenna certainly doesn't compare to a full sized base station antenna. It's all relative to something. Right?
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K1ZJH
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« Reply #22 on: July 31, 2015, 02:16:27 PM »

For the same length antenna, 9 dB strongly suggests a unidirectional pattern, with all of the dipoles favoring one direction.  If the dipoles were spread at 90 degrees, the pattern would be omni directional, with 6 dB gain.
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W9IQ
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Posts: 1845




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« Reply #23 on: July 31, 2015, 04:17:28 PM »

I have successfully used Diamond and Comet antennas for my repeaters and have diplexed VHF and UHF repeaters to the same antenna.

To ensure long life, remove the elements from the radome, silver solder all joints, and reinstall. If there is a rubber gland on any radome joint, remove them, lubricate fully with silicone o-ring lubricant to keep them from drying out and failing, and reinstall. Use a bit of Loctite on any external screws or fasteners.

After several years of service in harsh weather, I have had zero antenna problems. All of my antennas have been on the top of the tower. However, I doubt that these radomes would survive large chunks of ice falling on them if they are on the side of a commercial tower.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
AF6D
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Posts: 378


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« Reply #24 on: July 31, 2015, 06:21:39 PM »

Agreed as to both replies. Yes, a DB222 is a side-mounted 2-dipole array that is a 5.5dB cardioid pattern. If the elements are 180° opposite one another it becomes elliptical. My experience has shown that a 4dB decrease in RSSI is noticeable. In fact using RMD it shows that the RSSI expressed in dBm drops from -67dBm to -80dBm.

I like that you have been able to diplex a V and a U on one antenna. I know of a repeater here that does that and they are the top but side-mounted on a 200 foot tower in the desert. I too have a dual band that is at the top of an 80 foot tower and it goes snow, ice and rain every winter without trouble. Your silver solder technique might just be a good way to go and then using epoxy shrink tubing at the joints would be a good way to go. The O rings aren't that special.
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W9IQ
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Posts: 1845




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« Reply #25 on: July 31, 2015, 09:35:43 PM »

Unless your shrink tubing is UV rated and has a waterproof, heat activated adhesive on the inside, I won't bother since water will ingress anyway.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
AF6D
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« Reply #26 on: July 31, 2015, 10:04:58 PM »

I only use the best! :-)
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K1ZJH
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Posts: 3573




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« Reply #27 on: August 01, 2015, 03:55:24 PM »

Isopole is about the only ham grade antenna I'd consider for ham service.  Excellent low angle radiation pattern,due to proper decoupling.

Pete
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AF6D
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« Reply #28 on: August 01, 2015, 05:00:08 PM »

Did you mean for repeater use?
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W8JX
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Posts: 12372




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« Reply #29 on: August 04, 2015, 11:40:03 AM »

Try a Hustler G6 or G7 for 2 meters. I have had one up 40 feet for over 20 years and had zero problems with it and we have had some serious storms too including one that broke mast near base on my 5BTV.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
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