Advice on an alternative Low Band vehicle antenna

[unioner101]

I recently purchased a Motorola Syntor 7000x in low band. All of the area departments use low band dispatch (to avoid narrow-banding requirements and the cost of placing pagers) and operate on a trunked system(s). The Syntor is programmed is a both low end (33.00 mhz) and high end (46.00 mhz) low band frequencies.

Problem is I cannot put a standard low band antenna on my truck (tahoe) because I park in a parking garage everyday for work. Even if I make a hood mount (similar to the am/fm antenna) I still will not have enough clearance.

The solution I would like to try is a glass mount antenna, just mounted a bit lower on the rear quarter panel window (I figure I only have about 5 inches clearance above my roof). However I have been not been able to find a low band glass mount.

I have found a midland glass mount CB antenna, and also a 2M glass mount. Does anyone have any suggestion as to which would be better, or another idea all together. I will NOT be transmitting from the radio.

Thanks

 

[radioman2001]

If you are not going to transmit you can just use a piece of rg-58 stripped down to the 42 mhz wavelength. Either mount the center conduction accross the rear window if you have the radio mounted in back, or down the center or off to the side of the windshield if you mounted it under the front seat as I did. Now when you strip off the shielding don't cut it off keep it the same length as the center conductor for a true 1/4 wave antenna. For my 2009 Charger, I have the center conductor running down the center of the rear window and the shield grounded to the rear shelf.

 

[jim202]

I recently purchased a Motorola Syntor 7000x in low band. All of the area departments use low band dispatch (to avoid narrow-banding requirements and the cost of placing pagers) and operate on a trunked system(s). The Syntor is programmed is a both low end (33.00 mhz) and high end (46.00 mhz) low band frequencies.

Problem is I cannot put a standard low band antenna on my truck (tahoe) because I park in a parking garage everyday for work. Even if I make a hood mount (similar to the am/fm antenna) I still will not have enough clearance.

The solution I would like to try is a glass mount antenna, just mounted a bit lower on the rear quarter panel window (I figure I only have about 5 inches clearance above my roof). However I have been not been able to find a low band glass mount.

I have found a midland glass mount CB antenna, and also a 2M glass mount. Does anyone have any suggestion as to which would be better, or another idea all together. I will NOT be transmitting from the radio.

Thanks

Let me ask this simple question, "Are you trying to describe a Syntor X9000 radio?" If so, you have the wrong numbers. I am not aware of any radio with the model you have stated.

Now on to the antenna. To my knowledge, there is no glass mount antenna made for low band use.

You can make this work with 2 separate antennas mounted on the truck. One antenna for the 33 MHz frequency and one for the 46 MHz frequency. Next you need to cut the feed line to each antenna very carefully to an exact length. You put the feed line for the 33 MHz frequency on the 46 MHz antenna and the feed line for the 46 MHz frequency on the 33 MHz antenna. Then combine the both of them at the radio with a UHF T connector.

I have had to do this a couple of time for a fire chief's vehicle in the past. It works great, but takes some careful measurements and the use of a calculator. When you get all done, the use of an SWR meter will verify your work.

By the way, I own a number of the Syntor X9000 radios on low band. They are one of the best and flexible radios that Motorola ever made. Even the current top of the line radios don't have the functions and features that the Syntor X9000 has and the different flexibility that the radio can be made to do. With different software, you can end up with about 255 channels and 32 PL tones available to you. There is a normal limit of 64 channels in the scan list. With a firmware mod, that can be extended to 128 channels or more. I have never been able to put the firmware mod in my radios, so don't have any hands on with it.

 

[radioman2001]

jim202 I think what you are describing is a bit overkill for a radio that's only going to monitor. Yes if you need to transmit on both hose frequencies, then you will need to what you did, but for RX only a piece of wire hung out the back of the radio will do. BTW I agree the X9000 is one of the best Motorola made, I have about 10 of them in various flavors, and they have been the best radios with the least problems I have ever had.

 

[mrweather]

Get something like a Larsen NMO34B coil, a spring and a whip. The spring will allow the antenna to bend over and not be damaged.

 

[Thunderknight]

For receiving only, even a VHF High band whip will work. If you can hood mount a 19" 1/4 VHF whip, that will be okay for *receiving*.
It will not work as well as a full length low band whip, but it will work to some extent.
I would be concerned about using a 2M glass mount because it's possible there could be some tuning in the coupler box that could cause it to be less responsive to frqeuencies outside the intended range.. A CB glass mount might provide better results.

 

[tglendye]

I agree w/ a VHF-hi 1/4 antenna for receiving. Also, have you thought about running a splitter to your AM/FM antenna? I know there are users that have had other experiences, but I have used these in the past and had good results. Since you are not transmitting on the radio, there is no need for overkill IMO.

 

[Thunderknight]

Todd, that's a good point on the splitter. I've seen the Antenna Specialists one on eBay recently.

 

[prcguy]

I would recommend an NMO mount on an angle bracket near the cowl across from your AM/FM antenna and use an old Antenna Specialists MON series scanner antenna. These are long but will bend out of the way just fine when mounted at hood level and going through parking garages.

The A/S MON series is probably the best VHF lo/VHF hi/UHF scanner antennas I've ever used and the low band portion resonates around 33MHz from the factory and can be trimmed for anywhere in the band. They also have some promising band width and if you tune it for around 40MHz it should be very usable across your needed range.

The Austin Spectra is a similar but shorter antenna that can also be tuned for VHF lo but its much narrower band width on VHF lo than the A/S MON series.

I've also made a passive resistive matching network for using any low power radio on a standard 31ish inch long AM/FM car antenna. The performance is not great but it did surprise me when I could key up most any 6m repeater in my area from a good 40-50mi around using a 5w handheld feeding the matching box and my AM/AM truck antenna.
prcguy

 

[unioner101]

Thanks everyone for your input...It is greatly appreciated. Right now I am leaning towards trying the AM/FM radio antenna spliter. But it is good to have other backups ideas in case I find the performance is not optimum.

 

[tglendye]

...have you thought about running a splitter to your AM/FM antenna? I know there are users that have had other experiences, but I have used these in the past and had good results...

I should have stated that my results were good on VHF-lo/hi and UHF. Good luck!

 

[mjthomas59]

I think a question that may have been skipped over is how robust is this system? And how far out to the fringes of the system are you planning to monitor? Are you trying to hear just dispatch or do you want to hear the trucks/apparatus/ etc

You don't necessarily need a fender mount 1/4 wave antenna thats say 70 inches tall, but a coupler to am/fm or a glass-mount antenna is certainly compromising your reception. Our highway patrol is still using lowband and most still use the fender-mount old school whip. The higher ups in the highway patrol are getting away from those and using the equivelant of a larsen nmo40c. The whip is about 49 inches tall. Aside from the annoyance of banging the whip on the parking garage roof I doubt you are actually going to do any damage to it. Another thought would be to measure the distance between your hood and the roof the parking garage. Buy a nmo style antenna and cut the whip just short enough to clear the parking garage, the longer you can leave that whip the better.

At the very least I would be looking at a nmo mount and 1/4 wave vhf-hi antenna. Not really any of my business but why would you want to go through the hassle of mounting that type of radio into a vehicle for receive only? A scanner is more flexible and easier to install. I get the argument that a motorola radio may receive better than a scanner, but that doesn't seem to be the issue here since you are coupling it with an extremely compromised antenna.

 

[Anderegg]

Police Antennas Stico Antenna Manufacturer in Buffalo NY | Sti-Co

I am purchasing one of these today.......hooking it up to a low-band Maxtrac......hoping for good results.

Paul

 

[prcguy]

The specs say .6 MHz band width. That means you can tune it for your 33MHz frequency and it will sort of work since is a compromise antenna and at 46MHz it will be really bad. I've measured a number of antennas for field strength on VHF lo and they can easily be 20dB, 30dB or more down when you go from 33 to 46MHz.

I think an A/S coupler on your existing AM/FM antenna would work better.
prcguy

Police Antennas Stico Antenna Manufacturer in Buffalo NY | Sti-Co

I am purchasing one of these today.......hooking it up to a low-band Maxtrac......hoping for good results.

Paul