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Date: 05/12/19 07:14
Mobile Antenna Question
Author: bnsf2001

Hello All, I'm looking for a good 1/4 wave magnetic mount antenna(tuned to the railroad band) for my scanner for use in my vehicle. I've heard that  Maxrad products are good. Any comments or suggestions are much appreciated! 



Date: 05/12/19 10:10
Re: Mobile Antenna Question
Author: TCnR

This had been coming up quite a bit, there's some interesting discussion, product names and sources in the archives using the TO search with 'Mag Mount'. A lot of it is based on availability of a particular brand.



Date: 05/12/19 18:11
Re: Mobile Antenna Question
Author: wa4umr

It's a question that pops up here about every other month.  I use an MFJ-1412 that I have had for probably 10 years or more. It's a dual band (UHF and VHF) and is one piece. Some have a coil enclosed in plastic but this one has the coil formed in the middle of the antenna wire itself. Noting to go wrong with a connection there. I use it on a mag-mount.  You can order it directly from MFJ Enterprises.  I have it mounted on a mag-mount.  They also have the mag-mount base.  It's cut for the 2-meter ham band (146MHz) but it works well for 161 MHz.  You could probably ct an inch of two off of the base and put it on the railroad frequencies.  

John

 



Date: 05/13/19 06:00
Re: Mobile Antenna Question
Author: alto_towerbob

I would give a recommendation to the Larsen NMOWBQB -- quarter wave antenna with spring.  Tuned for 150 - 170 mhz -- it's length of 17.5" is almost spot-on for the 160 mhz railroad band.  You will need a magnetic NMO style mount.  I got both from the The Antenna Farm on-line -- search under "Larsen NMOWBQB" ---- the mount I purchaed was NMOMMRDSSMA --- "SMA" is the connector at the end; you need to make sure what is correct for your antenna connector. 
Bob



Edited 1 time(s). Last edit at 05/13/19 10:30 by alto_towerbob.



Date: 05/15/19 19:36
Re: Mobile Antenna Question
Author: WW

For a 1/4 unity gain antenna, I often use the Comtelco A1511B antenna.  They are a physically robust antenna that works pretty well.  It must be cut (cutting chart supplied with the antenna) to the proper length to maximize reception in the 160 mHz band.

If one has to park in parking garages or other places with low clearance where a roof-mounted antenna may not clear,  I recommend the Sti-co Flexi-whip antennas.  They won't break and are very robust.  They can be hard to find and are not cheap, but their physical flexibility is great.  Also, they are a pretty thin antenna, so they tend to be fairly unnoticeable on a vehicle.  Law enforcement uses them quite a bit on unmarked vehicles for this very reason.

I've used (and still use) both of these antennas on my personal vehicles.

These antennas have an NMO thread, so will screw on to an NMO magnetic base. 



Edited 2 time(s). Last edit at 05/15/19 19:38 by WW.



Date: 05/18/19 09:17
Re: Mobile Antenna Question
Author: RFandPFan

For what its worth, I was told by our local Motorola technician that a permanently mounted antenna on the vehicle roof provides the optimal ground plane and improves reception over a magnetic mount.



Date: 05/18/19 11:48
Re: Mobile Antenna Question
Author: WW

RFandPFan Wrote:
-------------------------------------------------------
> For what its worth, I was told by our local
> Motorola technician that a permanently mounted
> antenna on the vehicle roof provides the optimal
> ground plane and improves reception over a
> magnetic mount.

Often true, though I've gotten good results from some mag mounts if the antenna is placed in an optimum location on the roof.  Where mag mounts often perfomrm poorly is more due to the quality of the mag mount antenna.  Many of the "full package" mag mounts (mount and antenna all in one) have antennas cut for broad band or just aren't as good a quality.  Best bet is to get a good mag mount base, usually with an NMO thread, then screw a high qaulity antenna onto the base.  I've found that those combinations work nearly as well as a permanent mount IF the antenna is placed an optimum location on the roof.  Also, be careful about not smashing or crimping the antenna cable in the door or window seal coming into the vehilce.  If the outside shield of the cable is compromised, the reception of the antenna can be nearly totally destroyed.



Date: 05/18/19 21:02
Re: Mobile Antenna Question
Author: TCnR

We've had some discussion about drilling holes into the roof of a modern car, I was surprised to hear that there may be sensors, or wire harnesses up there.

Optimal is a pretty tough description to use with RF and antennas, there's always something a little bit better for a reason no one saw the first time. An 'optimal' antenna is often dulled by too much cable or a bad connector, or oxidation, corrosion, etc.

Most of us agree though, that placing the antenna up high with a 1/4 wavelength of metal surface around it is about as good as it gets.



Edited 1 time(s). Last edit at 05/18/19 21:10 by TCnR.



Date: 05/19/19 05:42
Re: Mobile Antenna Question
Author: RFandPFan

WW Wrote:

  Also, be careful
> about not smashing or crimping the antenna cable
> in the door or window seal coming into the
> vehilce.  If the outside shield of the cable is
> compromised, the reception of the antenna can be
> nearly totally destroyed.

Very good info, often overlooked.



Date: 05/19/19 07:54
Re: Mobile Antenna Question
Author: WW

TCnR Wrote:
-------------------------------------------------------
> We've had some discussion about drilling holes
> into the roof of a modern car, I was surprised to
> hear that there may be sensors, or wire harnesses
> up there.

I have often advised that permanent antenna mounting on a vehicle is best left to reputable professional radio shops.  They know how to do it without harming other wiring or electronics on the vehicle.  They also know where the most optimum mounting locations are.  They also know how to mount radios, run cables, etc. where they will not interfere with things like air bags.  In some vehicles, an imprudently mounted radio in the path of an air bag deployment can turn the radio into a cannonball if the bag deploys in an accident.



Date: 05/24/19 21:19
Re: Mobile Antenna Question
Author: bodkin6071

Tram 1121. Have several and they are exceptional at reception.



Date: 05/25/19 16:48
Re: Mobile Antenna Question
Author: RFandPFan

WW Wrote:

> I have often advised that permanent antenna
> mounting on a vehicle is best left to reputable
> professional radio shops.  They know how to do it
> without harming other wiring or electronics on the
> vehicle.  They also know where the most optimum
> mounting locations are.  They also know how to
> mount radios, run cables, etc. where they will not
> interfere with things like air bags.  In some
> vehicles, an imprudently mounted radio in the path
> of an air bag deployment can turn the radio into a
> cannonball if the bag deploys in an accident.

Excellent point!  I recently had a antenna mount installed by a local Motorola dealer that handled our police cruisers before I retired.  They were careful to remove the headliner when drilling the hole and routing the cable to ensure it didn't interfere with anything.



Date: 06/07/19 12:18
Re: Mobile Antenna Question
Author: railrob

Our radio dealer switched our ambulances to STI-CO flexi-whip antennas after we kept snapping off the all  metal ones. These are able to be tied in knots with out breaking. Liked them so much I had them put on the roof of my SUV. Very good reception and no breakage !



Date: 06/08/19 09:30
Re: Mobile Antenna Question
Author: RFandPFan

railrob Wrote:
-------------------------------------------------------
> Our radio dealer switched our ambulances to STI-CO
> flexi-whip antennas after we kept snapping off the
> all  metal ones. These are able to be tied in
> knots with out breaking. Liked them so much I had
> them put on the roof of my SUV. Very good
> reception and no breakage !

That's the one I use (easier to park in my garage), I also get great reception with it.



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