Low Band BNC antenna needed

Anderegg · #1 (**permalink**) 10-08-2012, 9:19 PM

I live/work in San Diego County California, and the entire county is 800Mhz trunked, except for one entity, the CHP (California Highway Patrol).

All of the scanners in my vehicle run through a 1/4 wave 800 antenna, and an 800 specific multi-coupler. While this means perfect reception for all the 800 stuff, it disallows reception of anything else due to the filtering and antenna size.

CHP has a website that shows all of the traffic accidents, but what is not available on their CAD is pursuits. I have a 396XT in my car, and I want to set-up a low band antenna for use on CHP to monitor pursuits. I want to use the BNC mount that Radio Shack sells that goes on the top of the window when you roll it up. I need an antenna specifically for the 39MHz frequency range, something that can withstand 80MPH wind at speed. I don't care how big or ugly it is, since I will keep it in the trunk and just throw it on when there is a chase.

So what would be my best BNC option, or would it be more practical to just use one of my NMO magnet mounts with a 4 foot low band whip?

Paul Anderegg

prcguy · #2 (**permalink**) 10-08-2012, 10:43 PM

I have some tunable rubber ducks somewhere and they are about 10" long but would not do well at high speed. A Larsen low band NMO is not that big and probably your best choice, or scan the CHP extender freq 154.905 which will light up when you get within a mile or so of a CHP car.
prcguy

Quote:

Originally Posted by Anderegg

I live/work in San Diego County California, and the entire county is 800Mhz trunked, except for one entity, the CHP (California Highway Patrol).

All of the scanners in my vehicle run through a 1/4 wave 800 antenna, and an 800 specific multi-coupler. While this means perfect reception for all the 800 stuff, it disallows reception of anything else due to the filtering and antenna size.

CHP has a website that shows all of the traffic accidents, but what is not available on their CAD is pursuits. I have a 396XT in my car, and I want to set-up a low band antenna for use on CHP to monitor pursuits. I want to use the BNC mount that Radio Shack sells that goes on the top of the window when you roll it up. I need an antenna specifically for the 39MHz frequency range, something that can withstand 80MPH wind at speed. I don't care how big or ugly it is, since I will keep it in the trunk and just throw it on when there is a chase.

So what would be my best BNC option, or would it be more practical to just use one of my NMO magnet mounts with a 4 foot low band whip?

Paul Anderegg

Anderegg · #3 (**permalink**) 10-08-2012, 10:56 PM

I enable both the VHF and 700MHz on my handheld when I am on a CHP scene, or near it, so I have that covered. I am just dead in the water when a chase occurs unless they patch it on SDPD patch or LE Command. I already have a magnet mount NMO, but I kinda want something more compact and easy to deploy during a pursuit. Does the rubber ducky get decent reception on the 39 MHz repeaters?

By the way, the new 700MHz extenders sound like GARBAGE, especially when there is freeway traffic noise in the background.

Paul

PJH · #4 (**permalink**) 10-08-2012, 11:28 PM

BNC and lowband in an ideal world do not play well together.

The San Diego offices are/were running the system in duplex mode for awhile (at least in the summer) so you should be able to hear everything with just a VHF 1/4 wave antenna.

Why are you using a multicoupler with the scanner? What else are you running or what did someone sell you on? I think the bigger picture is what are you running and what are your needs? I am assuming your an independent news guy.

For my personal/professional thing, I have found that a Diamond MX3000 works very well, and everything is being ran off of a Comtelco 1/4 VHF antenna with no noticable degragation.

If you really want optimum CHP reception, get yourself a lip mount/trunk mount 1/4 lowband antenna.... or at least even a VHF antenna and run it straight. You cannot cheap on lowband or you will severly limit what you want to hear.

FWIW, between ducting and doing things right, I have RX them in my vehicle from the eastern seaboard to the Rocky Mountains. Its all in the antenna system. Rubber duckies are almost as bad as glass mount antenna's, just slightly better.

Anderegg · #5 (**permalink**) 10-09-2012, 12:32 AM

Yes I am a news photog. When I worked in Los Angeles, I had all my scanners running off a black NMO 1/4 antenna, worked well for VHF/UHF/800, better than any dedicated "scanner antenna" I ever tried.

The San Diego trunked systems are very difficult to monitor in the metro area, as they barely come in at all in many places. To minimize signal loss, I installed a powered 800MHz specific multi-coupler. Splitting a bunch of scanners off one coax is a death sentence for 800 signals here in SD. The amplified multi-coupler gives me loss-less reception on my 800 scanners. I run 3 scanners off three ports on it, then the fourth port feeds 3 Motorolas with a buncha cheap splitters. The Motorolas don't care about signal loss, since they receive the special secret Motorola only frequency feeds that scanners can't tune. :-P

Anyway, the main post. I used to have a 5/8 wave 10 foot long quarter panel whip on my Crown Vic......I could receive San Francisco with it! HAHA. Now a days I am looking for low profile, as I drive a small SUV with only a black 800 1/4 wave on it. Since rubber duckies are out, I guess I will go with a low band whip. Anyone know a decent one (NMO) I can tune for 39MHz? I am going to discount the VHF 1/4, since if I have to deploy it I want all the signal I can get! :-)

Paul

gewecke · #6 (**permalink**) 10-09-2012, 2:24 AM

Quote:

Originally Posted by Anderegg

Yes I am a news photog. When I worked in Los Angeles, I had all my scanners running off a black NMO 1/4 antenna, worked well for VHF/UHF/800, better than any dedicated "scanner antenna" I ever tried.

The San Diego trunked systems are very difficult to monitor in the metro area, as they barely come in at all in many places. To minimize signal loss, I installed a powered 800MHz specific multi-coupler. Splitting a bunch of scanners off one coax is a death sentence for 800 signals here in SD. The amplified multi-coupler gives me loss-less reception on my 800 scanners. I run 3 scanners off three ports on it, then the fourth port feeds 3 Motorolas with a buncha cheap splitters. The Motorolas don't care about signal loss, since they receive the special secret Motorola only frequency feeds that scanners can't tune. :-P

Anyway, the main post. I used to have a 5/8 wave 10 foot long quarter panel whip on my Crown Vic......I could receive San Francisco with it! HAHA. Now a days I am looking for low profile, as I drive a small SUV with only a black 800 1/4 wave on it. Since rubber duckies are out, I guess I will go with a low band whip. Anyone know a decent one (NMO) I can tune for 39MHz? I am going to discount the VHF 1/4, since if I have to deploy it I want all the signal I can get! :-)

Paul

A Larsen NMO 34 will tune there.

Larsen NMO34 [NMO34] - $36.95 : The Antenna Farm :: , Your Two Way Radio Source!

73,
n9zas

Anderegg · #7 (**permalink**) 10-09-2012, 3:47 AM

I just dropped the hammer on a Larsen NMO40, 40-50 MHz. I am assuming that it comes pre-cut for 40 MHz, and only needs to be tuned if you go towards the 50 MHz end of the spectrum. I got the spring option, the black finish option, and the Jack in the Box head option with next day air, and it only came to $92.78.

Paul

gewecke · #8 (**permalink**) 10-09-2012, 4:44 AM

Quote:

Originally Posted by Anderegg

I just dropped the hammer on a Larsen NMO40, 40-50 MHz. I am assuming that it comes pre-cut for 40 MHz, and only needs to be tuned if you go towards the 50 MHz end of the spectrum. I got the spring option, the black finish option, and the Jack in the Box head option with next day air, and it only came to $92.78.

Paul

Ok, I wish you luck.

A lot of guys are budget minded, so that's why I suggested the one above.

73,
n9zas

PJH · #9 (**permalink**) 10-09-2012, 8:08 AM

A 1/4 wave comtelco lip mount on a Chevy SUV will be about as tall a the roof rack when properly cut. Not all "powered products" really work that well especially feeding a bunch of scanners/radios. It's just simple math.

Having been a Pacific Veach resident, the trs puts out a good signal. I'd have a competent radio shop (pref one that serves public safety aka what the city or county uses) and have it done correctly. Hint: don't talk to the sales guys but the service guys. You really do need some multiple antennae

Anderegg · #10 (**permalink**) 12-29-2012, 9:55 PM

Out of curiosity, how well do you think a splitter off of my Honda AM/FM fender car radio antenna would work on low band? I would be willing to buy such a device simply to see how the reception is.....can anyone recommend a specific product.....hoping to be able to pull the BNC end like 3-4 feet out from behind the dash, could probably use a F-F adapter for that.

For now I am using a Motorola HT750 lowband, and I can RX Oceanside CHP with the built in antenna from 47th and Federal.....go Moto!

Paul