Running one scanner with multiple antennas

[danb474]

I can't find a suitable diplexer for the life of me. Oh yeah, let me also mention that I currently use a 50' run of quad-shielded RG-6 PL-259 to BNC to connect the RS cheapo antenna to my scanner.

Would I be just as well to put up a Diamond discone and use LMR-400. I'm just not sure if that will give me that much more 800 MHz signal to make the frequencies all break the squelch on this scanner.

My thought is that if I add a second antenna (Antenex 800 MHz gain), that signal will be somewhat lost with a diplexer and the extra connections.

Any recommendations? Again, I currently have a RS 20-176 mounted on a 5' mast at my rooftop, 50' of quad shielded RG-6 from Home Depot.

All I need is to improve my 800 MHz receive. The system is received at about 50% as good as I'd like.

 

[zz0468]

I can't find a suitable diplexer for the life of me. Oh yeah, let me also mention that I currently use a 50' run of quad-shielded RG-6 PL-259 to BNC to connect the RS cheapo antenna to my scanner.</quote]

I don't know why you can't find a diplexer. There's tons of them out there. Search the threads here.

Would I be just as well to put up a Diamond discone and use LMR-400. I'm just not sure if that will give me that much more 800 MHz signal to make the frequencies all break the squelch on this scanner.

Maybe. 50' isn't a huge run of cable, and if your RG6 is decent, switching to LMR400 may gain you a db or two, but you're unlikely to notice.

My thought is that if I add a second antenna (Antenex 800 MHz gain), that signal will be somewhat lost with a diplexer and the extra connections.

How much gain on the Antenex? So, you gain a db or so with LMR400, you lose it again in the diplexer - and you've gained what?

Any recommendations? Again, I currently have a RS 20-176 mounted on a 5' mast at my rooftop, 50' of quad shielded RG-6 from Home Depot.

All I need is to improve my 800 MHz receive. The system is received at about 50% as good as I'd like.

You don't state whether you need to listen to other bands besides 800, or whether you're trying to listen to more than one 800 system. The answers to those questions would impact any recommendation that I would make.

 

[danb474]

I would still like to monitor the CHP on VHF Low, the local PD on VHF High, Civilian and Mil Air. There is only one 800 Mhz system I'm trying to monitor.

I don't have any help with the install and would rather install an omni that I don't need to point and re-point. The Antenex I was looking at has 6db of gain (or so it claims). It's a 5' vertical.

Would I be better off just using the Antenex w/o a diplexer? Will it receive signals (albeit weak) on VHF Low/High, and the airbands?

Is a good discone going to give me much better 800 Mhz receive than the RS 20-176? If the answer is yes, maybe that's where I should head with this project.

 

[iMONITOR]

I would still like to monitor the CHP on VHF Low, the local PD on VHF High, Civilian and Mil Air. There is only one 800 Mhz system I'm trying to monitor.

I don't have any help with the install and would rather install an omni that I don't need to point and re-point. The Antenex I was looking at has 6db of gain (or so it claims). It's a 5' vertical.

Would I be better off just using the Antenex w/o a diplexer? Will it receive signals (albeit weak) on VHF Low/High, and the airbands?

Is a good discone going to give me much better 800 Mhz receive than the RS 20-176? If the answer is yes, maybe that's where I should head with this project.

This is an antenna that I seldom recommend because it is expensive. But for your needs I think it's perfect. It even has a built-in diplexer. I've used this antenna personally it it performed very well.

AOR SA7000
http://www.universal-radio.com/catalog/wideant/3755.html

 

[iMONITOR]

Here's a couple pictures of the AOR SA7000:

 

[danb474]

This is an antenna that I seldom recommend because it is expensive. But for your needs I think it's perfect. It even has a built-in diplexer. I've used this antenna personally it it performed very well.

AOR SA7000
http://www.universal-radio.com/catalog/wideant/3755.html

Thanks for your input. I checked that one out, and I think it's more than I need. It is two antennas with a diplexer, one for up to 30 MHz, the other above 30 Mhz. I don't need to monitor anything under 40 MHz, so one of the antennas on that setup is not needed.

I guess I'm looking for a good wideband that performs well on 800 MHz. Does one exist? I heard the Par MON-3 performs well on 800, but I got in touch with them and it's currently not in production. Any other suggestions?

 

[iMONITOR]

Thanks for your input. I checked that one out, and I think it's more than I need. It is two antennas with a diplexer, one for up to 30 MHz, the other above 30 Mhz. I don't need to monitor anything under 40 MHz, so one of the antennas on that setup is not needed.

I think you may have misread the specs. It starts at 30 MHz, not below. So it's 30MHz~2GHz.

 

[W6KRU]

I think you may have misread the specs. It starts at 30 MHz, not below. So it's 30MHz~2GHz.

No, you misread it. It is good from 30 KHz to 2 GHz. One antenna is strictly HF.

 

[iMONITOR]

No, you misread it. It is good from 30 KHz to 2 GHz. One antenna is strictly HF.

My bad! You're correct. I was accidentally looking at the specs for the DA3000. Sorry.

In any event, I found that to be one of the best performers on VHF/Lo. The length of that longest element is much closer to being a 30MHz antenna than a 30KHz for sure!

 

[danb474]

In any event, I found that to be one of the best performers on VHF/Lo. The length of that longest element is much closer to being a 30MHz antenna than a 30KHz for sure!

Still looking for a good 800 MHz performer if anyone has any recommendations. Or would an 800-only antenna still receive nearby VHF-Hi decently????

 

[W6KRU]

Still looking for a good 800 MHz performer if anyone has any recommendations. Or would an 800-only antenna still receive nearby VHF-Hi decently????

I like this one a lot. It is better than the RhC77 for 800 MHz and its pretty close to my external antenna. The price was right as well.

 

[danb474]

I like this one a lot. It is better than the RhC77 for 800 MHz and its pretty close to my external antenna. The price was right as well.

Sorry, looking for a good base antenna on 800, that is also wideband to some extent (at least down to VHF-Hi). I currently have the RS 20-176, and it doesn't do well for me on 800.

 

[W6KRU]

Sorry, looking for a good base antenna on 800, that is also wideband to some extent (at least down to VHF-Hi). I currently have the RS 20-176, and it doesn't do well for me on 800.

Sorry, I missed the base part.

 

[bgkoe]

My antenna array is simple, I run the antenna coax from my
pro 97 to a Diawa CS-4 antenna switch sitting next to the 97 so I can
switch between four antennas with one motion. This allows me to use
several antennas of different configurations when necessary. My marine
antenna is the 8' model from RS and it's great (a weak plug but that
was changed), it works better than the rest on weak marine signals.
Bill K.

 

[OpSec]

Here's one for you guys:

I need to combine a 800 MHz 6db vertical, a VHF-Hi 6db vertical and a yet-to-be-installed UHF antenna into a Uniden BC-780XLT. These antennas are on a tower with hardline into the building and terminate into Polyphasher's. From the hardline, there is an ~80 foot feedline run to the scanner. I can not get the feedline run any shorter. I am in a high signal area, so I have some leeway on feedline loss, etc.

In addition to the multiple antennas, I need to notch out our VHF data freq on the same tower, about 80 feet above the scanner's VHF antenna.

What diplexers are decent for this application? Would some quad-shield RG-6 be acceptable feedline? Currently it's RG-58 (not my install!).

 

[lmrtek]

It's ALL in the sesign of the antenna.

Many antenna designs can cover 25mhz to 2ghz without the need for additional antennas.

When you introduce combiners and splitters you simply add loss to the system

 

[btritch]

Diplexers or Triplexers are the accepted industry method of combining multiple antennas into one receiver.

The Electroline multicouplers are used to distribute ONE signal to multiple receivers, not multiple antennas to one receiver.

That one signal can come from a single antenna or the output of a diplexer or triplexer. (combining 2 or 3 separate antennas).

I use a custom triplexer fed by band-specific antennas, then that ONE output is fed into a multicoupler, and finally to the multiple receivers.

Thus, I have 3 band-specific antennas feed into the triplexer, the single output from the triplexer feeding into the multicoupler, which feeds 8 separate receivers with just enough amplification to have 0db loss throughout the system.

I have a multi band scantenna now I use and it works fine until I want to listen to 800 MHZ 40 miles away, Then I find myself changing connections back and forth, The way I understand this is a Diplexer will bring in both signals but at different times. I have a multi band and a directional 800 mhz yagi I want to run at different times without having to switch cables constantly. Will a diplexer work for this?
Where Can I get one if it will or what I need if it won't?
Any help will be appreciated, Thanks!

 

[N_Jay]

Many antenna designs can cover 25mhz to 2ghz without the need for additional antennas.

Which ones?

 

[kpoe_28]

Lets say I wanted to hook up two anntena's to my scanner, I only listen to 154 and 155mhz, I have a homemade VHF Slim Jim up about 90 feet with RG6 coax and it does a really good job but there is a town about 20 miles away that does not use a repeater and sometimes it's hard to hear the cars. I was thinking about putting together a VHF 4 element yagi and mount it up at 75 foot with RG11 coax and point it at the town that I'm having trouble with, Can I hook two VHF antenna's together without using a diplexer or a combiner, just use a "T" for the RG6 and RG11 in the house just before the scanner?


Thanks,
Kevin

 

[N_Jay]

Not without getting random and unpredictable results.