I'm finally going to order an antenna for my TM-281a that I picked up for receiving railroad (and eventually use for amateur radio once I get my license). I have been wanting to get the Larsen NMO150 5/8 wave antenna, but I'm wondering if the gain from using a 5/8 wave or even 1/2 wave is worth it over a standard 1/4 wave. The antenna will more than likely be tuned to focus on the rail band until I get my ham license, so that should help a bit. Any advice would be appreciated as I'll be ordering it tomorrow morning. Thanks
1/4 wave vs 5/8 wave for Rail RX
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reconrider8
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I run that same antenna the 5/8 wave trimmed to ch 32 and I get traffic a good ways 10-15 miles give or take but it depends on conditions/weather/terrain and a bunch of other things
mmckenna
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1/4 wave antennas have a lot of bandwidth. I use them almost exclusively.
I just swept the one on my truck, and I have it set for lowest SWR (1.03:1) at 146.000MHz. Up around 160, the SWR is about 1.3:1.
Hard to beat 1/4 waves for basic simplicity, low price, and low profile.
5/8ths work well, but they'll fold over quite a bit at highway speeds, and that can change their resonance slightly. Not enough to be an issue, though.
I just swept the one on my truck, and I have it set for lowest SWR (1.03:1) at 146.000MHz. Up around 160, the SWR is about 1.3:1.
Hard to beat 1/4 waves for basic simplicity, low price, and low profile.
5/8ths work well, but they'll fold over quite a bit at highway speeds, and that can change their resonance slightly. Not enough to be an issue, though.
go the the 1/4 wave. i have a 1/2 wave on my truck and it works great
I've found that as far as magnet mounts go (Never had any others) that the bigger antennas just work better. I had a Larsen 5/8 NMO on a mag mount for years and it worked great, I didn't even touch it, the SWR was perfect on 146MHZ and it was much better than the two whips I actually tuned for railband. Someone stole it off my truck years ago when I was shopping and I never replaced it.
I went ahead and just went with the 5/8 wave Larsen, I'll compare it to the 1/4 wave Laird I already have on my scanner (replacing it with a Larsen scanner antenna), trying to decide if I should keep the 5/8 tuned to 144-146 range or tune it up around 160 (primary channels are 160.230 and 161.250 so finding a happy medium will be interesting)
For what it's worth, the type of antenna you choose should also depend on your terrain. 1/4 wave antennas a great for close in coverage when the transmitters you are tying to monitor are placed up high, such as atop buildings, mountains, etc. The 1/4 antenna pattern looks towards the sky and is a great choice for urban areas such as Philadelphia, New York, and Chicago. 5/8 wave antennas are an excellent choice for horizon coverage in rural flat terrain areas such as the Mid-West and Florida. These antennas have sort of a globe pattern straight out to the distance; they'll give you the best gain figure in this sort of terrain; however, in urban areas you may notice dead spots because of shadowing and other affects due to their pattern. 1/2 wave antennas are a good compromise between the two; great for urban or rural areas if your a frequent traveller to both types of terrain.
Everyone's opinions will differ on what brand is better; however, for me personally, I love the Larsen product line for several reasons. First and foremost is they're service, you can call them right here in the U.S. and get a live person who's is very helpful. Second is the waterproof seal they provide for 3/4" hole mounting; that rubber gasket has been on my vehicles for 10+ years and have not once leaked; best seal in the business in my opinion. Third is there offerings for amateur radio use, you simply cannot beat the NMO2/70 antenna. I have several, but my original one I purchased back in 1994 is still going strong and in-service today.
My setup is the Larsen 2/70NMO (1/2 wave) for the dual band ham transceiver, then I have the Larsen 440C (5/8 wave) for the MOTOTRBO radio. If I were adding an antenna just for railroad use, it would certainly be the 5/8 wave; but again, I'm in the Mid-West and here it would be the best choice; however, if I moved back to Philadelphia, I'd go with the 1/2 wave as terrain varies throughout that region.
Good luck with your decision and let us know the comparison for your area.
Everyone's opinions will differ on what brand is better; however, for me personally, I love the Larsen product line for several reasons. First and foremost is they're service, you can call them right here in the U.S. and get a live person who's is very helpful. Second is the waterproof seal they provide for 3/4" hole mounting; that rubber gasket has been on my vehicles for 10+ years and have not once leaked; best seal in the business in my opinion. Third is there offerings for amateur radio use, you simply cannot beat the NMO2/70 antenna. I have several, but my original one I purchased back in 1994 is still going strong and in-service today.
My setup is the Larsen 2/70NMO (1/2 wave) for the dual band ham transceiver, then I have the Larsen 440C (5/8 wave) for the MOTOTRBO radio. If I were adding an antenna just for railroad use, it would certainly be the 5/8 wave; but again, I'm in the Mid-West and here it would be the best choice; however, if I moved back to Philadelphia, I'd go with the 1/2 wave as terrain varies throughout that region.
Good luck with your decision and let us know the comparison for your area.
Update, the antennas came in, getting ready to take them out to the truck and install them (I also got a LArsen scanner antenna for normal scanner comms) and the radio. I still have the whip from the other antenna I ordered, so I'll cut it down tuned for 160, plus I also have the Laird 1/4 wave I can test to compare the three.
So they're installed, sitting at my house (about 6 miles WSW of Big Sandy Jct in Catlettsburg KY) I was picking up traffic at DK Cabin in Huntington (a good 15 miles away, and was very clear) & was also picking up the defect detector west of Russell, KY, at least 20 miles away), plus at some point I swear I heard Q711 (empty trash train) talking to the Russell yardmaster with no problem. And I have yet to tune it to 160...lol
You wouldn't notice a difference if you tuned it to 160. Isn't the area around there rather hilly? Just me but I would rather use a quarter wave for that terrain, but I like many other members agree the difference between 5/8 waves and quarter waves for receiving is pretty negligible. You did the most important thing and got a quality receiver.
I went ahead and had it tuned just to shorten it up a bit and keep it from hitting every low branch and drive thru possible. Still works great. Where my Kenwood portable starts to lose quite a bit, the 281 picks up perfectly. I've been able to sit on the hill at my station and hear traffic at least 10+ miles away. Hell, I got on the interstate near my house and heard a train calling signals at the farthest crossover in the next town over, which is a good 20 miles away from where I was. (Granted the on-ramp is up on a hill, but still)...I do have the Laird 1/4 wave still, I may do some comparison tests one day just to see how both pick up trackside. But the truck does look sexy with it now, pics will come tomorrow
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