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Repeater Antennae Recomendation

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Reggie_

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I'm looking to replace a Repeater system antennae for a vhf system operating at 172 Mhz. Recieving and transmitting Frequencies are 2 Mhz apart. The antennae being replaced is a commprod 266-70 which worked fine for about ten years, not so good the last two years. Can someone recommend a good antenna for a system with the following characteristics?
-Antenna to be mounted on 33 metre tower. Line of sight from top of tower is 8-15 miles all directions. We need reliable coverage for a 30 mile radius, which the commprod 266-70 did provide when it was new.
- Repeater system is a kenwood transmitting at about 25 watts with 200 feet of 1/2 inch heliax cable as transmission line.(I'm losing about 10 watts in the transmission line. Is this a normal amount?)
- I've had one local company quote a CRX 150 Laird, also a Sinclair 217, with a more expensive option being a Sinclair SD214. These antennaes look totally different. Which one will work best?
Thanks in advance for any reccomendations.
 

prcguy

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The Laird is junk, the 217 has no gain to speak of and the SD214 is what I would get out of the ones recommended. In areas where the other two antennas would be difficult to hear the larger SD214 would be heard much better.

Here would be another antenna to consider and less $$ than the SD214 with a little less performance but still a great antenna for your type of use. This would work much better than your original antenna.

I'm looking to replace a Repeater system antennae for a vhf system operating at 172 Mhz. Recieving and transmitting Frequencies are 2 Mhz apart. The antennae being replaced is a commprod 266-70 which worked fine for about ten years, not so good the last two years. Can someone recommend a good antenna for a system with the following characteristics?
-Antenna to be mounted on 33 metre tower. Line of sight from top of tower is 8-15 miles all directions. We need reliable coverage for a 30 mile radius, which the commprod 266-70 did provide when it was new.
- Repeater system is a kenwood transmitting at about 25 watts with 200 feet of 1/2 inch heliax cable as transmission line.(I'm losing about 10 watts in the transmission line. Is this a normal amount?)
- I've had one local company quote a CRX 150 Laird, also a Sinclair 217, with a more expensive option being a Sinclair SD214. These antennaes look totally different. Which one will work best?
Thanks in advance for any reccomendations.
 
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At 150 MHz 1/2" RFS heliax loses 1.21 dB/100', so you have 2.42 dB loss.
25 Watts = 44 dBm, 44 dBm - 2.4 dB = 41.6 dBm at the antenna.
41.6 dBm = 14.5 Watts so your 10 Watt loss is normal.
 

freddaniel

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It looks like your Heliax is OK. If you are suffering a loss of performance, I would bet on several drops of moisture in the antenna connector. Electrical tape is not enough to protect the connector from "evil" condensation, which accumulates over several months from rapid shifts from hot to cold and back, every day.

I would suggest using electrical tape to protect the connector finish, but cover it with two or three layers of Scotch 2242 or 130C thick rubber tape, at least 2 inches beyond the connectors. If you do not use the electrical tape first, when you eventually cut the rubber tape off, there will be an awful mess on the connectors. This tape is superior and will provide the necessary THERMAL insulation.

The very best VHF antenna is the Sinclair 214, as noted above. It will last forever and is very broadband.
 

kayn1n32008

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I’ll third the Sinclair SD214. If it’s installed properly, it will last for 30+ years.

Ultimately your budget will determine what antenna you go with. The only caveat is pay now or pay later. Buy a garbage antenna, and you may be paying riggers your replace it.

The commander may be a good option, but my preference is to avoid fiberglass if at all possible, especially if it will see ice, snow or wind. I have seen SD214’s mast bend from ice loading. Andrews/commscope DB and Most fibreglass antennas would fold like cheap lawn chairs.
 

ko6jw_2

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Take a look at Telewave. We are using a stacked dipole array. By adjusting the distance between elements and the distance from the mast you can control the directional pattern and (to some extent) the gain. Not cheap, but extremely rugged. Heliax of course.
 

Project25_MASTR

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I've been really fond of Telewave ANT150D and ANT450D antennas. You'll have to get with Telewave to for info on stacking and the phasing harness to build gain (I typically don't run them as stacked due to a need for maximum downward radiation).
 

Reggie_

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I would prefer the SD214 as well but I'm concerned about its overall weight (antenna will be mounted on safety cage on grain elevator) and for that reason I'm leaning a bit towards the commander 220. We don't ever get ice storms up here, we either get a little bit of rain or a little bit of snow, never too much of anything at once.
I looked at the Vertical radiation pattern for the Commander 220, and it looks kind of flat. Being that the top of the antenna will be up 130 feet, will I have any issues with reception (signal shooting over top) when I'm near the antenna? The terrain in the immediate vicinity of the antenna location is very flat
 

prcguy

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I have not checked the weight but in most cases an aluminum exposed dipole array is lighter weight than a super stationmaster. The antenna pattern will never be a problem on a 130ft tower and it should be virtually impossible to have a dead spot nearby. If it were a 10dB version on UHF then you might have a concern putting it on a 1,000ft or higher hill with no downtilt, but not a 5dB VHF version at 130ft.

I would prefer the SD214 as well but I'm concerned about its overall weight (antenna will be mounted on safety cage on grain elevator) and for that reason I'm leaning a bit towards the commander 220. We don't ever get ice storms up here, we either get a little bit of rain or a little bit of snow, never too much of anything at once.
I looked at the Vertical radiation pattern for the Commander 220, and it looks kind of flat. Being that the top of the antenna will be up 130 feet, will I have any issues with reception (signal shooting over top) when I'm near the antenna? The terrain in the immediate vicinity of the antenna location is very flat
 

prcguy

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I have not tried this brand but I've seen some test reports on stainless steel antennas where two identical antennas were tested for gain but one was aluminum and one was stainless. The stainless was down in gain by a noticeable amount, I forget the exact number but it was close to 1dB. Stainless is lossy at RF, especially VHF and above.

Anyone tried EMR's antenna line?
They have only been out a few months now.
 

mmckenna

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I have not tried this brand but I've seen some test reports on stainless steel antennas where two identical antennas were tested for gain but one was aluminum and one was stainless. The stainless was down in gain by a noticeable amount, I forget the exact number but it was close to 1dB. Stainless is lossy at RF, especially VHF and above.
Thanks, makes sense. I've got a couple of the Telewave and they've been fine. No reason to change.
 

Tech792

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Stay away from the Command antennas if possible. They don't last long. We've replaced 3 out of 5 within a few years.
 

mmckenna

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Telewave dipoles are great, powder coated and they last a long time, plus adjustable patterns.
Yeah, I have a couple installed up along some ridge lines above Big Sur, and they take quite a beating up there in the winter. No issues yet. Adjustable pattern has been useful, that and some mechanical downtilt has allowed us to cover into some deep canyons well.
 
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