External Antenna for 120-460 MHz

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Trenchdigger
Posts: 16
Joined: 11 Jan 2024 11:25
Location: Vermont

External Antenna for 120-460 MHz

Post by Trenchdigger »

I'm looking at a couple antennas Scott references in another thread:

Comet: https://www.hamradio.com/detail.cfm?pid=H0-006893
Scantenna: https://dpdproductions.com/products/omn ... se-antenna
Miltenna: https://dpdproductions.com/collections/ ... se-antenna

The miltenna is really appealing, but it "tops out" at 400MHz, and I want to scan as high as 465MHz ... will that work?

I have a metal roof, so I know I need to get an antenna as high as possible, and can do that. I'm at elevation, 2300 feet, but surrounded by taller mountains.

Also, I have direct line of sight to a repeater... Should I consider a directional antenna? If I do, I suspect that would negatively impact scanning for aircraft, correct?

Are there other antennas I should consider? I live in the middle of nowhere, no HOA, rules, neighbors, whatever. So I can pretty much do whatever I want... within a small budget. :) The previous owners had some sort of radio tower on the property; I'm guessing HAM, but the tower is gone, just a concrete pad and grey wires running from that to the cabin.

Thanks in advance!
deacon
Posts: 498
Joined: 26 Feb 2006 10:33
Location: North Mashpee

Re: External Antenna for 120-460 MHz

Post by deacon »

Good morning Digger,
Here is my two cents. I have room on my home.
I have a VHF antenna (Ringo Ranger) tuned to 155 mhz with an Advanced Receiver Research 150-160 pre-amp. I hear 171 mhz radios easily.

I have a custom DPD UHF antenna tuned to 468 mhz with a matching Advanced Receiver Research pre-amp.

I have a 800 mhz vertical from DPD productions with a matching Advanced Receiver Research 800 mhz pre-amp.

I have an 800 beam with another Advanced Receiver Research 800 mhz pre-amp. This antenna allows me to here RISCON (Rhode Island Trunk)
from Cape Cod.

I also have two Omni X antennas for local listening and a Channel Master SP-2 antenna for middle distance radios. All with per-amps.
For my low elevation, about 145" (high for Cape Cod), I do well. Elevation is KING with radio.

I hope this helps.
Chuck
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Scott
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Re: External Antenna for 120-460 MHz

Post by Scott »

Chuck has a great location that allows him to use preamps without any issues. I would caution in a lot of cases however to be careful. Preamps can make a marginal situation a lot worse. You say you're in the middle of nowhere which is a plus, but does that also mean in relation to strong transmitters and other potential interference sources. These are all things that need to be considered prior to any outside antenna installation, especially where preamplification is concerned.

The best solution is an antenna or antennas cut to the bands you wish to monitor, fed with quality coax such as LMR400. With that it is vital to understand that you must weatherproof the connection between coax and antenna. Water in the coax and antenna connection will make for a rapidly deteriorating situation and a loss of what could be several hundreds of dollars worth of equipment.

A good dual band antenna for monitoring is the Comet GP9NC. The C stands for commercial, meaning the commercial bands as opposed to the lower in frequency amateur radio bands. The GP9NC works well at 155 MHz and in the UHF 460 MHz range as well, and does a decent enough job above and below its point of resonance. I use one and it works well but I suffer at my location from the terrain around me. At the ground I'm about 90 feet above sea level. I do have 45' worth of tower, but because of strong nearby transmitters to include FM broadcast, pagers, Eversource, OneVoice DMR sites, etc., I find that a GP9NC mounted lower actually does a better overall job for me. As such, using preamps here is likely not going to work well for me although this spring I may try one with an 800 MHz yagi pointed west in an attempt to be able to monitor the closest RISCON system. On the plus side, during tropospheric band openings I have excellent results down into NY city and down the east coast, as far as North Carolina on 155 MHz during whopper openings, but those are all water paths.

One other thing. Make sure you've measured about 10 times for your cable length before purchasing it, especially if you're buying pre-cut lengths with connectors already installed. Most dealers will not take returns on coax.
Scott
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Trenchdigger
Posts: 16
Joined: 11 Jan 2024 11:25
Location: Vermont

Re: External Antenna for 120-460 MHz

Post by Trenchdigger »

The nearest communications tower is about 2.5 miles as the crow flies. I have my ATT signal booster pointed at it.

There are two more, about 8 miles away, one to the north and the other to the south.

Good tip on measuring the cable and weatherproofing. I'll be sure to do both. Grounding, too.

North Carolina! WOW!

Chuck ... That's a LOT of antennas! :cool:
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