Disapointing antenna results

[fredg]

Well I spent around $175 on a Larsen 2/70B antenna and the Atennex ground plane kit along with 50' of LMR400 cable.

Mounted about 25' up (clears the top of my house).

Results so far:

No better than the $25 RS 20-176 and Wal-Mart $20 RG6 cable I had before. In fact I am not sure it is even as good!

And yes, I am sure everything is connected correctly and tight.

I guess I just need to face the facts, I am out in the middle of nowhere and nothing is going to pull in signals that are not there!

EDIT:
I did just take a drive up out of the valley I live in and even at the top of the hill the reception sucks (with my 1/4 wave mobile) usually I can receive much better up there. So maybe conditions are just bad right now, but still, I have not noticed and MAJOR difference compared to the 20-176... should have bought the damn Scantenna!

 

[hoser147]

Fred, thats a kick in the a$$, Sorry to hear it didnt help. It sounds very much like the possibly the terrain in your location. If your sure that its not the antenna, you could always sell it on here and give the Scantenna a shot. Its just strange that the Radio Shack with the other coax did better. If you still have the old coax ran try to hook it to the antenna and see what happens if you get better reception You will know its somewhere in your connections of the feedline itself. Good Luck Hoser

 

[fredg]

Well after listening some more I did get a couple of weak UHF signals I have never heard before and I am getting my usual stuff about 25 miles away so things are working.

I just want that stuff 35 miles away!! Looks like a Yagi is the next thing to try....

I will know more tonight, once the sun goes down reception picks up so we will see......

 

[hoser147]

Sounds like you have used good quality stuff, but it kinda strange that you dont get more up on the hill. I live on flat terrain and normally get traffic up to 50 miles in most directions using a RS Discone , Yagi (800) and a RS 176. And Im up about 30-35ft. I got a tower this last year and Would very much like to get it up this year, but Im surrounded by big Oak trees and if I put it up Im afraid it will put me right in the middle of the canopy. But with Ohio weather It would be great most of the year. Just gottn keep on tinkerin, Good Luck Hoser

 

[Just_Me]

Why don't you do the math and see if a yagi is worth the effort.
It's all in the dBs.

 

[blueangel-eric]

Well after listening some more I did get a couple of weak UHF signals I have never heard before and I am getting my usual stuff about 25 miles away so things are working.

I just want that stuff 35 miles away!! Looks like a Yagi is the next thing to try....

I will know more tonight, once the sun goes down reception picks up so we will see......

The Grove scanner beam antenna is something to check out. I've always wanted one and if i get a house again i'm going to try to budget one. though i have a tv antenna i chopped up to make into a scanner beam although no good in my apartment. but it worked good last i used it.

eric burris

 

[blueangel-eric]

Fred, thats a kick in the a$$, Sorry to hear it didnt help. It sounds very much like the possibly the terrain in your location. If your sure that its not the antenna, you could always sell it on here and give the Scantenna a shot. Its just strange that the Radio Shack with the other coax did better. If you still have the old coax ran try to hook it to the antenna and see what happens if you get better reception You will know its somewhere in your connections of the feedline itself. Good Luck Hoser

Like where i lived last the signals were a dead spot where i lived. up the street things were better. too many trees and a few feet lower in elevation on my block. I got a traintenna and something like LMR400 and did no better then the cheap radio shack mini 8 coax!!!!!! and my other antennas.

Eric Burris kc0ldt

 

[fredg]

Thanks guys... I asked this question in another thread but I will ask again here..

I have the Larsen NMO 2/70B with the (loading?) coil. See pic

I was checking out my Larsen antenna and noticed something strange. When I put one end of my VOM to the threaded stud on top of the black coil and the other end to the threaded NMO part under the coil I get a dead short. This means my vertical element is connected to ground.

When I go to the center of the coil (the underside where the center wire of the cable wold go) it doesn't seem to be hooked to anything.

Any ideas??

 

[fredg]

I emailed Glenn at Scanners Unlimited, he got back to me right away, and on a Sunday!!

Here is what he said:

"It is abosultely normal for any antenna with a base loading coil to show a short with a DC V.O.M. (volt ohmeter). The reason the antenna coil shows a short is that it is a coil (also known as an inductor) and an inductor is a short to DC current, but not to AC, and the radio wave it is receiving is an AC wave electrically."

He offered to send me a replacement antenna if I have a concern about mine being defective (I bought the 2/70 from him). He is going to double check a coil with a VOM and see if it behaves the same.

Make a note folks, I doubt you can get this kind of service from ANY other vendor! Scanners Unlimited is a class act!

 

[DPD1]

Well I spent around $175 on a Larsen 2/70B antenna and the Atennex ground plane kit along with 50' of LMR400 cable.

Mounted about 25' up (clears the top of my house).

Results so far:

No better than the $25 RS 20-176 and Wal-Mart $20 RG6 cable I had before. In fact I am not sure it is even as good!

And yes, I am sure everything is connected correctly and tight.

I guess I just need to face the facts, I am out in the middle of nowhere and nothing is going to pull in signals that are not there!

EDIT:
I did just take a drive up out of the valley I live in and even at the top of the hill the reception sucks (with my 1/4 wave mobile) usually I can receive much better up there. So maybe conditions are just bad right now, but still, I have not noticed and MAJOR difference compared to the 20-176... should have bought the damn Scantenna!

A dedicated base might have been a hair better, just because the element material is going to be better than stainless like the mobile has. But even though you are basically going from a 2M ground plane, to another 2M antenna... for a 5/8, it seems a little odd that there wouldn't be a fairly good bump up. Of course everybody has their own definition of 'improvement'.

Dave
www.DPDProductions.com
Antennas & Accessories for the RF Professional & Radio Hobbyist

 

[CHAWMAN24]

The Grove scanner beam antenna is something to check out. I've always wanted one and if i get a house again i'm going to try to budget one. though i have a tv antenna i chopped up to make into a scanner beam although no good in my apartment. but it worked good last i used it.

eric burris

I bought a Grove scanner beam about 1 year ago and have been extremely pleased with its performance. I have it mounted on a 25ft mast with Digital Cable TV/ Satellite coax and a Rotor. I'm not sure what the actual name of the coax is , but it is heavier than standard Cable TV RG-6 and seems to work real well. I am using a BC895XLT with the beam. I live in Central Pennsylvania south of the City of Altoona. I am able to receive signals from as far south as Allegany Co.Maryland to as far north as Elk County Pa. All around 50 miles from my location. With the rotor i am able to switch the beam direction for better reception of the distant signals. All of the local stuff comes in loud and clear and with some experimenting i was able to find a good pointing direction where all the desired signals come in good. I had a RS discone before the beam as my primary antenna and with the beam i have been able to pull in signals that i couldn't before with the discone.

 

[Just_Me]

. . .it seems a little odd that there wouldn't be a fairly good bump up. . . .

How many dB do you think the "bump" should be?

 

[hoser147]

Like where i lived last the signals were a dead spot where i lived. up the street things were better. too many trees and a few feet lower in elevation on my block. I got a traintenna and something like LMR400 and did no better then the cheap radio shack mini 8 coax!!!!!! and my other antennas.

Eric Burris kc0ldt

Yep Eric thats kinda what I had in mind, It might be just as good at the height Im at due to being below alot of the foilage in the canopy of the trees................Hoser

 

[blueangel-eric]

Yep Eric thats kinda what I had in mind, It might be just as good at the height Im at due to being below alot of the foilage in the canopy of the trees................Hoser

i should mention my handheld would pick up some Railroad hot box detector signals better at ground level then a fancy base antenna 20ft in the air in the yard there!!!!

Eric Burris

 

[fredg]

Once the sun went down last night things picked up, then I hooked up my GRE Super Amp and I got some distant signals.

There was one VHF high frequency that seemed to die with this antenna as compared to the little Radio Shack 20-176, but that may have just been the conditions.

I would say that it is working at least as well as my old Channel Master Monitenna at this point. I guess I was hoping for a miracle!

The little GRE Super Amplifier, http://www.greamerica.com/scanner_accessories.html scroll down, helped quite a bit as well....

I guess this really goes to show how good the little 20-176 really is....

 

[LordJ]

For vhf signals, it's hard to beat the 20-176.

 

[key2_altfire]

The LMR-400 might not have much of an edge over cheaper cables until you hit 800 MHz and higher. At 150 MHz, loss diff between "standard" RG-6 and LMR-400 is approximately 1 dB or less.

 

[SkipSanders]

I did just take a drive up out of the valley I live in and even at the top of the hill the reception sucks (with my 1/4 wave mobile)
-------------
Valley. Death to reception.

No amount of antenna or cable is going to fix your basic problem, which is, you don't have line of sight. Signals at VHF and above do not pass through hills. If you can't SEE it from your antenna, you can't expect to receive it. At UHF and above, trees and other foliage contributes significant signal loss, as well.

VHF range is almost totally about antenna height, yours and the transmitter's, and intervening terrain/buildings/foliage.

A 25' above ground antenna is good for 5-10 miles. If the transmitting antenna is 100' up, it contributes another 10-20 miles. If a mountain is in between, signal is essentially zero. 10x antenna gain times zero signal is still zero.

None of this adresses the design of the system you're trying to hear. Some systems are very deliberately designed to have no signal outside their intended area of coverage, especially trunked systems. Others try for very wide coverage.

You need to determine who you're trying to listen to, where their nearest/highest transmitter site is (FCC records), and determine whether there is any line of sight.

 

[SkipSanders]

If you actually want to see where, and where not, you have viable coverage, you can get the capable, but somewhat complex to learn, program 'Radio Mobile', at:

http://www.cplus.org/rmw/english1.html

This free program will let you download digital elevation data, enter your location and antenna height, and the location and antenna height of the other end, and give you full visual info on where there is, and is not, line of sight.

 

[rankin39]

Well I spent around $175 on a Larsen 2/70B antenna and the Atennex ground plane kit along with 50' of LMR400 cable.

Mounted about 25' up (clears the top of my house).

Results so far:

No better than the $25 RS 20-176 and Wal-Mart $20 RG6 cable I had before. In fact I am not sure it is even as good!

Because the antenna element is at d.c. ground (as the dealer said), it is only going to give the advertised gain in or near the 2 meter and 70 cm. ham bands that it is designed for. The farther from the ham bands you tune, the more it's going to "look" grounded to your radio. I once tried using a Larsen 2/70 as a mobile low-band antenna before I realized how it was configured and never received a single signal. I'm just not sure how well we should expect the 2/70 to work 10 or 15 MHz. outside the ham bands. If you're listening in the ham bands, the 2/70 should give you 3 db. or so of gain over the ground plane.
Bob, w0nxn