Antenna for mobile scanner

[UPTRAIN]

I was gonna put a "blister" like UP's AC units on the roof for antennas but "the boss" (my wife) said no to that...oh well. [:P] [:D]

[Big_Boy_4005]

Thanks Stelli, sorry to turn this topic from mobile to fixed. Those are some interesting possibilities, and combined with what Larry has said, I'm getting excited!! My fridge, may be a lost cause, but the attic may hold great potential. I have 13 feet from joist to peak, putting me about 26 feet off the surrounding ground covered and dry. There are some hills around, but nothing major. One slight twist is that most of the trains are down in the river valley, about 100 foot verticle difference.

[Anonymous]

Reply to Big_Boy_4005: The Maxrad 5/8-wave mobile antenna I mentioned will work great in your house as well. I own a second one that spends most of its time attached to the top of my fridge. (I have a vaulted ceiling in the kitchen and living room which makes this possible.) Other times, it gets put on my wife's van or taken elsewhere. (The one installed on my SUV is too extensively wired through to the underdash scanner to be taken out at the drop of a hat.) Anyway, for the modest price, this antenna will work great for you in your home if there's room for it above your fridge, or on top of some other metal surface. A flat, metal surface underneath is important for best reception. The bonus will be that this antenna can also be taken with you when you "go mobile." If that's not an issue, you might be better off going with a mast antenna installed in your attic or on your roof, possibly more expensive and much more involved, but probably even better reception. The awesome reception I described earlier is actually what I get from my "fridge-mounted" antenna. Vehicle-mounted performance is even better, depending on where I'm driving, of course.

[Big_Boy_4005]

Thanks Guys, I have plenty of that kind of stuff hanging around here at the house. I even have the right type of connector for the radio. Time to tinker.

In this case I will want to shoot for a large chunk of the railroad band, and not just a channel. I have a book listing which railroads use which channels for what tracks and other purposes.

[tree68]

QUOTE: Originally posted by redflasher

the formula for vertical antenna length is:

468 divided by the frequency in megahertz divided by 2

for example:

here in Minnesota 468/BNSF road frequency 160.920=2.9 feet/2=1.45 feet for 1/4 wave antenna

I usually figure on 18" for VHF-High, which squares almost exactly with redflasher's computations. Of course, I'm usually dealing with several freq's in the range. You could also double that for a half wave antenna.

There are several ways you can make an antenna. If you can acquire 4 or 5 stainless, aluminum, or copper rods (1/8" would be fine, it should be quite stiff, tho), you can build a nice "ground plane" antenna. One vertical, the other 3 or 4 horizontal, equally spaced. The vertical gets connected to the center conductor of your coax, the horizontals get attached to the braided shield. The vertical needs to be isolated from the horizontal members, and the horizontals need to be connected together. Plastic would be the best for a hub, but a wood dowl might work, if you keep it dry. Do a search on "ground plane antenna" and you can probably turn up some plans.

(Added later) So I went back and searched and found this: http://www.northcountryradio.com/Articles/groundplane.htm. It is so simple as to be, well, simple. Some good stiff #10 solid copper wire would work really well.

A real quick and dirty is to carefully remove the outer cover from the end of the coax, for the length mentioned above (ie, about 18" or 36"). Then carefully roll the braided shield back over the outer sheath. When you get done, you have the center conductor sticking out and the braid back over the rest of the cable, presumably for equal lengths. You can then secure the end of the center conductor as high as possible, and, of course, connect the other end to your scanner. If you wanted to use that outside, I'd recommend some shrink tubing to reduce the possibility of moisture getting into the cable.

The same concept is used in many commercial antennas, although applied much differently.

Given your high ground, you may be able to get reception of a lot more than 15 miles with a good antenna.

[redflasher1]

the formula for vertical antenna length is:

468 divided by the frequency in megahertz divided by 2

for example:

here in Minnesota 468/BNSF road frequency 160.920=2.9 feet/2=1.45 feet for 1/4 wave antenna

[Big_Boy_4005]

Hmmmm, that sounds very interesting and encouraging. My application would be for home use. A 15 mile range would be spectacular. I live on high ground, and could listen to activity on 9 subdivisions of 3 class 1 railroads. For mobile use, I don't mind the standard "rubber ducky", because if I am out and about , the tracks won't be far away.[swg]

Is it possible to make your own antenna for home use????

[Anonymous]

Rudy's right. The Maxrad 5/8-wave is the best mobile whip money can buy. It's about $60-70 from Railcom (see ad in Trains), price includes tuning (trimming) to RR band. Ships in a sturdy tube which you can later use to check the antenna in as baggage when flying to a destination where you can mount it on a rental or other vehicle. (STA may inspect it, but won't prevent it from flying.) Tell Railcom what kind of connector you want on it. Mine picks up detectors 25 miles away across hilly terrain, locos 40 miles away across hilly terrain (no repeaters involved, and none of this "close to the track" business mentioned earlier), etc. As for those Radio Shack telescoping antennas for hand-held use, they DO dramatically improve reception over rubby duckies as long as you follow the accompanying literature that tells what length to adjust the antenna to for the RR band. When hiking over rough terrain or through trees/brush, I'll use my rubber antenna, then switch to the metal one when I'm in ready to set up the tripods and wait.

[RudyRockvilleMD]

I have a Bearcat BC 100XL scanner with a "Rubber Ducky" antenna which does reasonably well in pulling in transmissions in flat territory. I use the scanner with the "Rubber Ducky" antenna when I am trackside I recently got a MaxRad antenna with a magnetic base which I mount on the roof of my station wagon. It is tuned to the 161MHz carrier frequency which allows my scanner to pick up train and defect detector transmissions 25 miles away.

As far as I know there are very few restrictions on the use of scanners. Kentucky and Indiana forbid both the portable (at trackside or in public places) and the mobile use of scanners without a permit. Florida, New York, Michigan, and Minnesota forbid the use of scanners in cars without a permit. The best advice I herd was to be discreet when using a scanner.

[rrock]

I have an aged Radio Shack PRO-28 scanner that I can't seem to kill. Came equipped with a "rubber ducky" antenna.

A generic magnetic base car roof antenna (also purchased from Radio Shack) I've used for some time receives transmissions roughly four times the distance that the rubber ducky antenna will.

A few months ago I purchased a replacement for the rubber ducky from a ham radio outlet, optimised for the 160MHz bandwidth. Pulls in stations roughly three times more distant than the rubber ducky- a major improvement. Wish I had purchased the better on-scanner antenna years ago.

As has been pointed out in previous posts, many conditions affect reception range.

In this area, BNSF uses dipole or folded dipole (figure-of-eight radiation/reception) antennas for many of their repeaters, with the dipole radiation pattern pointing along the tracks. My home is a couple of miles from a nearby repeater, but I receive no transmissions from it- I'm situated at a prefect right angle to the repeater antenna, in the null of the dipole.

Scanners are legal in this area. Subjectively, it seems to me that many railroad employees assume you are a serious (and hopefully safe and courteous) railfan if you have a scanner, and not some wacko that has happened along.

[tree68]

QUOTE: Originally posted by Doggy

How Much does one cost.

DOGGY

A professional quality antenna, with cable and connector would probably be in the $50 range, but I haven't gotten any lately, so can't say for sure. Look up radio in the yellow pages and give your local Motorola, GE, etc, dealer a call.
Tell them you need an antenna for 160 Mhz.

Might be more, might be less. If you're willing to settle for second hand, you might be able to get a deal. Don't forget you need to mount it -- magnetic, trunk clip, angle bracket - lots of choices.

[Anonymous]

How Much does one cost.

DOGGY

[Big_Boy_4005]

Mrlove, the transmission may be coming from the detector miles away, but the question that I raised, and Jackflash answered, has more to do with how close you are to the tracks, and not necessarily the transmission source. Because the transmission is directional, it is strong near the rails, but weakens quickly the further away you get.

My point here is, what you might think is a fancy high powered antenna, may be nothing more than good proximity to the transmission's signal path along the rails. How far are you from the nearest tracks? I am not trying to give you a hard time, just trying to undrestand better how the radio system works, and if changing the antenna has any real effect on range of reception.

[Anonymous]

the type of antenna that you want for your scanner will make or break the radio transmissions that you get plus the radio's sensitivity or whats called microvolts the lower the microvolt(s) the more sensitive the scanner is to pick up radio transmissions! also i had to try so many ant(s) before i finely got one that realy works and thank god i did! for example,i can hear the hotbox dector at mo.valley.at m.p.332.0 to my home at blair m.p.343.25 a distance of 11.25 miles.and can the train crews & the omaha dispatcher really good with just my hand held scanner radio,the bnc145 antenna i use does realy well on my scanner,so i hope this helps,mrlove.

[Big_Boy_4005]

I'm beginning to wonder here what advantage a different antenna would give. The problem may not be with your ability to listen, but the railroads ability to transmit. In other words no length of antenna will help the problem if you are not in the path of the transmission. The solution may be skip the antenna, and get closer to the tracks.

[tree68]

I think Indiana is also in the no mobile scanner group. I know MI and NY are. If you can justify it (not easy), MI will give you a permit.

The appropriate length for a high band antenna is about 18" (for quarter wave). You may see these on many utility vehicles, buses, even police and fire, depending on a number of factors. There are also base loaded antennas, which resemble CB antennas. Either will be an improvement over your rubber duck.

A good communications equipment company (one that handles commercial and public safety radios) will gladly sell you the appropriate antenna, even cut to length and with the right connector for the radio. It won't necessarily be cheap, unless you happen into one they have sitting around. A magnetic mount is most versatile, but there are body mounts that fasten into the fender by the hood or trunk, or if you are a real diehard, you could have it actually mounted on your roof or trunk deck. Not recommended for dad's car...

I have a 36" whip that serves to receive several bands in my truck. I can hear the DS for a pretty good distance, trains and other mobiles much less.

[Big_Boy_4005]

Thanks Jackflash, that's kind of what I thought was going on, I just wasn't sure how they were doing it. As a matter of fact, I think one of the sheds that houses some of the UP's radio equipment is near my house, about 3 miles away. Two problems though, not much traffic to listen to, and I'm not in the directional path. Oh well.

As far as whether scanners are legal in Minnesota, I'm guessing that they are. Mine is a hand held, and I'm not chasing police, fire, and ambulance, just trains, though the radio can pick up all of that too. I bought it in Minnesota, usually if something isn't legal stores in that state won't sell it, though that isn't ALWAYS the case.[swg]

[Anonymous]

QUOTE:
I also noticed that there are some on this thread to this point from MN, MO, IN, ILL, and even Canada. What does each of your states say about carrying a scanner in your vehicle? I believe in KY it is illegal but I am not sure.

Scanners are legal here in British Columbia.

I know for a fact you can't carry them in KY . There are only a few US states where you can't, I think New York is another one....

Chances are as long as you keep your scanner low-profile nothing will happen.

[Jackflash]

but am curious how far railroad radio signals will travel away from the tracks. Most crew mobile radios are very low power, and won't work beyond a mile or two (something like double max train length).


Railroads use remote base stations every 20 or so miles and these remote
bases use directional antennas that focus the transmitted and received
signals up and down the right of way, with very little signal going into areas
away from the ROW, Locomotive radios do not use directional antennas
but the antenna is not high up in the air either so the signal wont travel
as far, but the high up directional remote base will pick it up a long distance
away. jackflash

[Anonymous]

I use a radio shack pro93 scanner with a bnc145 antenna from scanner world and this antenna does very well to my scanner,but not as good as the moble railcom whip.

[louisnash]

I just recently purchased a RadioShack Pro-89 scanner and it seems to pick up quite well. Our work sits right beside NS tracks 20 miles south of Cincinnati and I have been getting some of the yard chatter. About 5 miles more south of our work NS crosses over CSX and I get some from them also. Always here the defect detector.

My house sits about 3/4 miles from the rails in town and I get quite a bit from NS also.

I also noticed that there are some on this thread to this point from MN, MO, IN, ILL, and even Canada. What does each of your states say about carrying a scanner in your vehicle? I believe in KY it is illegal but I am not sure.

Brian (KY)

[Big_Boy_4005]

As long as we are on the subject, I have a Radio Shack pro-79. I'm happy with the antenna, but am curious how far railroad radio signals will travel away from the tracks. Most crew mobile radios are very low power, and won't work beyond a mile or two (something like double max train length). I'm guessing that dipatcher and train radios are more powerful, but again as I move away from the rails I lose the signal. There must be repeaters along the line confining the signal to almost a linear path along the tracks.

[Anonymous]

http://eje.railfan.net/railradioonline/


I've heard lots of good things about the traintenna (link above)
Not really for your portable needs, but great for your scanner when at home.

Anyone who wants to listen in on the train radio frequencies but doesn't have a scanner (like me) can check out

http://www.railroadradio.net/index.php

You can listen to a bunch of different frequencies over the internet.

[Anonymous]

I actually used the Radio Shack mobile mount scanner antenna that looks like a cellular antenna for my car. Easy to mount and use. But I also bought a scanner designed to be mounted in the car that fits under the dash. Sweet little Bearcat that is only about 1 inch tall by 5 inches wide. It's great to have it there any time I want. I wouldn't invest in some of those other longer extendable antennas that Radio Shack sells for handheld scanners. The short rubber ones work just as well from my experience..

Mark

[Jackflash]

The rubber duck antenna that came with the scanner is a "one size fits all"
it is not tuned for any particular frequency, go to a two-way radio shop
and see if you can get a antenna that is "cut" for 161.000 MHz, but
keep the original antenna, as reception will fall off the 161 antenna the
farther you get from 161 MHz. also bear in mind a rubber duck antenna
is not very efficient, an outside antenna will always work better. jackflash

[Modelcar]

...I have a Radio-Shack Pro-51 scanner and for some time now I've wanted to check if a stronger antenna is avalable for it...I believe I did see in the past of a longer rubber duckey antenna being available but I just never stopped and checked about it yet. This will remind me again and maybe I can stop in at one of our stores to check. For some reason I believe there is one available. [8D]

[kschmidt]

Great Question,

I was also wondering if there is an antenna available for a mobile scanner with a BNC connector that is tuned to the railroad frequencies. The rubber ducks work OK, but there must be something that doesn't have to attached to the car. Thanks

Keith Schmidt

[eolafan]

I have a Radio Shack mobile scanner with a short (about six inches) rubber antenna. I also have a magnetic mount antenna for the trunk of my car but it is not always convenient to use when driving. Can anybody suggest a replacement antenna for the scanner (the short kind) that might work better than the original equipment one? Thanks.[:)]