Antenna Choice help

[Ncfirewire]

Hi i currently use an anli a-1000 on my roof with lmr240 cable the antenna specs are as follows 143-148/ 430-460 with a 8.5/11.8 db gain my main concern is the range between 420& 465 with a week analog system at 460 range. But with new systems popping up in joining counties about 20 miles away using Digital on 851.000 range and another on 761 range. i would like to start listening to them as well. but i cant lose the 460 analog channel.

I am guessing my current antenna will not pick up the 700 and 800 band

i was looking at either the Diamond X700HNA which has a gain of 13 but i dont know if it will work on a 700 and 800 band?
The other was a Diamond discone D130NJ it only has a gain of 2 so i wonder if this will be worse for my week analog 460 channel?
Also will going up to lmr400 over the 240 be a difference i will see?
And in theory how many miles away should i expect to pick up a digital signal on the 700 and 800 band?

Any suggestions would greatly be appreciated

Thanks
Eric

 

[mmckenna]

Any piece of metal you stick up in the air is going to receive something, no matter the frequency, design, etc.
The question is "how well will it work".
The answer to that is "depends". It depends on too many variables for us to guess at.

Only way for you to know for sure is to try. I would recommend not buying anything new until you do that.

My bigger concern would be the LMR-240 and how long that run of cable is. If it's a long run, you are going to lose a lot of the higher frequencies due to cable loss. If you can receive the new stuff on 700 and 800MHz, but it's a bit weak, you'd probably do better by upgrading your cable.

As for "how many miles"? Again, entirely depends. most of these frequencies you are referring to are line of sight. If your antenna can see their antenna, then it's going to work. On the other hand, if you have a lot of hills, buildings, trees, etc. between you and them, there's going to be a problem, and buying a different antenna may not address it at all.

 

[Ncfirewire]

Any piece of metal you stick up in the air is going to receive something, no matter the frequency, design, etc.
The question is "how well will it work".
The answer to that is "depends". It depends on too many variables for us to guess at.

Only way for you to know for sure is to try. I would recommend not buying anything new until you do that.

My bigger concern would be the LMR-240 and how long that run of cable is. If it's a long run, you are going to lose a lot of the higher frequencies due to cable loss. If you can receive the new stuff on 700 and 800MHz, but it's a bit weak, you'd probably do better by upgrading your cable.

As for "how many miles"? Again, entirely depends. most of these frequencies you are referring to are line of sight. If your antenna can see their antenna, then it's going to work. On the other hand, if you have a lot of hills, buildings, trees, etc. between you and them, there's going to be a problem, and buying a different antenna may not address it at all.

Currently with the anli antenna I can not receive the 700-800 at all and I assumed that it was because of the antenna itself. As far is the lmr 240 it is a 50 foot run

 

[TailGator911]

I have the Diamond D130NJ with 2db gain and it was too much on my local digital simulcast system to where my radios were overloaded (towers are only a few miles away) so I switched to a directional yagi and fixed that problem. If you are using your D130NJ on a digital 800mhz system you may experience the same problem. Did not work so well with my Ohio MARCS P25 Phase I digital simulcast system. But, that's just my circumstances. Everyone's situation is unique and varied, depending on your stats (location, range, antennas, RF, etc)

As for all other frequencies and bands, the D130NJ is an absolutely awesome antenna.

JD
kf4anc

EDIT: Just a brief note on the durability of the Diamond D130NJ. Lived in Tampa area for 22 years and my first one survived 3 hurricanes and a few tropical storms before being taken out by a tree limb in 2002. My second one withstood 4 hurricanes in a row in 2004 without so much as losing a radial. That same hurricane series took out the entire solar panel system on the roof that heated my pool, 125 ft of privacy fence, 2 trees, and my entire 'Florida' room (flimsy screened in patio). My Cushcraft AR-270b also survived. I have both of those antennas on my roof here in Ohio. The Diamond D130NJ is one tough antenna, too.

 

[Ncfirewire]

I have the Diamond D130NJ with 2db gain and it was too much on my local digital simulcast system to where my radios were overloaded (towers are only a few miles away) so I switched to a directional yagi and fixed that problem. If you are using your D130NJ on a digital 800mhz system you may experience the same problem. Did not work so well with my Ohio MARCS P25 Phase I digital simulcast system. But, that's just my circumstances. Everyone's situation is unique and varied, depending on your stats (location, range, antennas, RF, etc)

As for all other frequencies and bands, the D130NJ is an absolutely awesome antenna.

JD
kf4anc

The 2 systems that use the 700 800 digital p25 are bout about 25 miles from me and since I only have my anli A 1000 that won't work at all I'm just trying to figure out if the two I listed possibly could.

 

[TailGator911]

Well, I depend on my D130 for uhf stuff around me and uhf DMR and it performs great in the 460mhz band. With your 700/800 system being 25 mi away I doubt that 2db gain would overload you and it seems a good distance and that antenna is great for distance. IMO, your choice of the D130 would suit you well for pulling in the weak 400mhz signals while at the same time handling the P25 25mi away.

 

[Ncfirewire]

But if I am having trouble on that weak analog 460 channel now with my antenna that has 10 dB gain. and is 18 ft tall in theory wouldn't the discone that is only 2db and much shorter be worse?

 

[TailGator911]

It has been my personal experience that too much gain on an antenna can sometimes cause more problems than it fixes. Sometimes more is less and can attenuate the signal. Years ago I had a signal amplifier for my scanner and the more gain I added, the less I could hear the systems in my immediate area. Too much gain worked the opposite of how I thought it would work. Once I lowered it down to under 5db I could hear everything quite well. Once I figured out I was amplifying noise right along with the signal I took the amplifier out.

 

[Ubbe]

Do you have only one scanner and what lenght of coax do you have?

Get a used second hand scanner and put up an additional antenna and coax. Discone antennas work best at 100Mhz and then loose a lot of signal up in the 700-800MHz range. Your Anvil 1000 antenna are a chinese knockoff of a japanese Diamond X510 and the anvil specs says that SWR are below 2:1 within +/-4MHz from the center frequency, which means at 460MHz the gain have dropped to a very low value.

If the 700-800MHz transmitters are all in one direction you could get a directional yagi antenna, something like a $50 cost. You could use RG6 coax that are pretty much the same specs as a LMR400. If you have to receive signals from several directions you must use a vertical antenna but as it's also are cellular frequencies in that band you don't have to pay much for a cellular 10dBi antenna.

If you still only want to use one scanner you could use a diplexer filter to combine signals below 500MHz with signals above 500Mhz from two different antennas.

As a first step I would put up another antenna and RG6 coax and experiment with that, how it performs at 460MHz and other frequencies. I have a 13dBi 440MHz yagi and it seems to receive all kinds of frequencies like VHF and Airband from all directions almost as good as a 1/4 GP specially made for those frequencies. You could try and connect the coaxes together and other things to try and receive the things you want without first buying expensive special filters, or a second scanner.

/Ubbe

 

[Ncfirewire]

Do you have only one scanner and what lenght of coax do you have?

Get a used second hand scanner and put up an additional antenna and coax. Discone antennas work best at 100Mhz and then loose a lot of signal up in the 700-800MHz range. Your Anvil 1000 antenna are a chinese knockoff of a japanese Diamond X510 and the anvil specs says that SWR are below 2:1 within +/-4MHz from the center frequency, which means at 460MHz the gain have dropped to a very low value.

If the 700-800MHz transmitters are all in one direction you could get a directional yagi antenna, something like a $50 cost. You could use RG6 coax that are pretty much the same specs as a LMR400. If you have to receive signals from several directions you must use a vertical antenna but as it's also are cellular frequencies in that band you don't have to pay much for a cellular 10dBi antenna.

If you still only want to use one scanner you could use a diplexer filter to combine signals below 500MHz with signals above 500Mhz from two different antennas.

As a first step I would put up another antenna and RG6 coax and experiment with that, how it performs at 460MHz and other frequencies. I have a 13dBi 440MHz yagi and it seems to receive all kinds of frequencies like VHF and Airband from all directions almost as good as a 1/4 GP specially made for those frequencies. You could try and connect the coaxes together and other things to try and receive the things you want without first buying expensive special filters, or a second scanner.

/Ubbe

I Think the first thing i am going to do is switch the cable from an lmr 240 knock off to a real lmr 400 i also wonder how much i lost having 2 pl259 to n adapters on each end of the cable? the new cable will be n with no adapters

 

[mmckenna]

OK, here's the loss numbers for real Times Microwave LMR cables at a 50 foot run using a frequency of 851MHz:
LMR-240 3.6dB loss
LMR-400 1.9dB loss
I see where you said you were using "knock off LMR-400", we'll guess that performed a bit worse...
The extra adapters are not helping, and unless you really waterproofed everything well, figure there is some good loss in those. Usually, on their own, figure on a few tents of a Db for each connector, usually not something you ear would be able to hear.

So, you'll gain a bit of improvement with changing out the cable and removing the adapters, but I doubt that alone is going to fix this.

You said that the performance was marginal on UHF, near the antennas claimed coverage.
That's raises some concerns about the antenna. I looked up the "anli a-1000" online, and I'm not impressed. The few reviews I could find were not all supportive.

If it works to your satisfaction on the 2 meter and 70cm band, then keep it for that.
But if you want a good scanner antenna, I think you need to get something a bit better, improve your coaxial cable situation (especially if you want to do 700-800MHz stuff) and maybe get that antenna up higher.

Without knowing if you have line of sight to the other systems you want to listen to, there's not really any good way for us to tell you if it's going to work or not.
One thing you can try is to take your scanner with a short jumper up on the roof and connect directly to the antenna and see if it works. That can tell you if it's a cable issue. You can also take the stock antenna up there with you and see if you can hear the system with that. That'll sort of indicate if it's even possible.

I'd say spend some time with Google Earth using some of their tools to see if you have an unobstructed shot at the other systems. If you don't, then no amount of antenna will fix this.

 

[Ncfirewire]

OK, here's the loss numbers for real Times Microwave LMR cables at a 50 foot run using a frequency of 851MHz:
LMR-240 3.6dB loss
LMR-400 1.9dB loss
I see where you said you were using "knock off LMR-400", we'll guess that performed a bit worse...
The extra adapters are not helping, and unless you really waterproofed everything well, figure there is some good loss in those. Usually, on their own, figure on a few tents of a Db for each connector, usually not something you ear would be able to hear.

So, you'll gain a bit of improvement with changing out the cable and removing the adapters, but I doubt that alone is going to fix this.

You said that the performance was marginal on UHF, near the antennas claimed coverage.
That's raises some concerns about the antenna. I looked up the "anli a-1000" online, and I'm not impressed. The few reviews I could find were not all supportive.

If it works to your satisfaction on the 2 meter and 70cm band, then keep it for that.
But if you want a good scanner antenna, I think you need to get something a bit better, improve your coaxial cable situation (especially if you want to do 700-800MHz stuff) and maybe get that antenna up higher.

Without knowing if you have line of sight to the other systems you want to listen to, there's not really any good way for us to tell you if it's going to work or not.
One thing you can try is to take your scanner with a short jumper up on the roof and connect directly to the antenna and see if it works. That can tell you if it's a cable issue. You can also take the stock antenna up there with you and see if you can hear the system with that. That'll sort of indicate if it's even possible.

I'd say spend some time with Google Earth using some of their tools to see if you have an unobstructed shot at the other systems. If you don't, then no amount of antenna will fix this.[/QUOTE
If the cable does not help much do you think that discone I listed in my initial post would be an improvement over the anli 1000 that I am using?

 

[Ncfirewire]

OK, here's the loss numbers for real Times Microwave LMR cables at a 50 foot run using a frequency of 851MHz:
LMR-240 3.6dB loss
LMR-400 1.9dB loss
I see where you said you were using "knock off LMR-400", we'll guess that performed a bit worse...
The extra adapters are not helping, and unless you really waterproofed everything well, figure there is some good loss in those. Usually, on their own, figure on a few tents of a Db for each connector, usually not something you ear would be able to hear.

So, you'll gain a bit of improvement with changing out the cable and removing the adapters, but I doubt that alone is going to fix this.

You said that the performance was marginal on UHF, near the antennas claimed coverage.
That's raises some concerns about the antenna. I looked up the "anli a-1000" online, and I'm not impressed. The few reviews I could find were not all supportive.

If it works to your satisfaction on the 2 meter and 70cm band, then keep it for that.
But if you want a good scanner antenna, I think you need to get something a bit better, improve your coaxial cable situation (especially if you want to do 700-800MHz stuff) and maybe get that antenna up higher.

Without knowing if you have line of sight to the other systems you want to listen to, there's not really any good way for us to tell you if it's going to work or not.
One thing you can try is to take your scanner with a short jumper up on the roof and connect directly to the antenna and see if it works. That can tell you if it's a cable issue. You can also take the stock antenna up there with you and see if you can hear the system with that. That'll sort of indicate if it's even possible.

I'd say spend some time with Google Earth using some of their tools to see if you have an unobstructed shot at the other systems. If you don't, then no amount of antenna will fix this.

If the cable does not help much do you think that discone I listed in my initial post would be an improvement over the anli 1000 that I am using?

 

[mmckenna]

If the cable does not help much do you think that discone I listed in my initial post would be an improvement over the anli 1000 that I am using?

I cannot answer that. You'd need to do some of the testing I outlined above. There's too many variables involved for someone on the internet not familiar with your exact location to be able to answer.

You need to figure out where the issue is. To do that, try the following steps in this order:

1. Take a short coaxial jumper with your scanner up to the antenna. Connect directly to the antenna and see if the signal improves.
- If it does, that means that you either have cable issues (bad connector, corrosion, etc) or your cable has too much loss. You'd need to replace your cable with a type that exhibits lower loss.
- If it does NOT, that means that either your antenna is the issue or that the signal is too weak for you to receive reliably with that antenna.

2. Take the scanner and stock antenna up on the roof to where the antenna is. Try using the stock antenna and see if you can hear the 700/800MHz systems you want to listen to, and if the UHF system sounds better.
- If it works better, that means that your roof top antenna system is likely insufficient in some way. You'll need to consider a new antenna and coaxial cable.
- If it does NOT, that means that you are not in a location that is going to be able to receive those systems very well. Adding antenna gain -might- help, but probably not enough to be reliable.

3. Take the scanner somewhere away from your house, preferably up on a hill, top of a building, something. See if the reception improves.
- If it works better, that means your location may be the issue. That could be local noise, your location doesn't have line of sight to the systems, your antenna system is lacking, but that your scanner is working correctly.
- If it does NOT, Then it may be impossible to do what you want with any amount of reasonable antenna system.

I really don't want to see you go out and spend a bunch of money on cable and antennas without doing some testing first. You need to narrow down what the issue is and then approach from that direction. Throwing wads of money at random parts rarely works out well.