Railroad amp

[reconrider8]

I just got my Austin Spectra an i love how much clearer and further it can reach but i was wondering what would be a good amp to add for a mobile railfan rig like i have?

 

[n5ims]

For railfan listening, instead of a very wide bandwidth (but no gain) antenna and adding an amp (to increase the noise as well as the signal) it may be better to use a VHF-Hi band only antenna that has gain instead. You won't get results in areas way away from the railroad frequencies (33 MHz and 865 MHz for two examples) but you'll get much better results where you're listening (161 MHz or so).

An antenna tuned for where you listen is nearly always better than a generic "DC to Daylight" one. Something like this (http://www.theantennafarm.com/catal...nfo&cPath=191_192_195_456_460&products_id=738) should do nicely. If you cut it for 161 MHz or so (using this as your guide http://www.pulseelectronics.com/download/3150/nmo_vhf_series_cut_chartspdf) you'll have a tuned 3 dBd gain antenna specific for your desired frequency range. You'll have double the signal strength and reduction in signals where you don't want them without anything that needs a power cord.

 

[reconrider8]

So what would something like a traintenna and an amp do? Since that's tuned and would have an amp

 

[radioalbany]

GaAs FET amps

Not sure how much you want to spend. I've used Advanced Receiver Research amps for years on commercial bands and love them. The GaAs version is the one to get, in this case the P160VDG. The amps are quite rugged, have good noise figure and are available with type-N connectors, which i like.

www.advancedreciever.com

Good luck with whatever you decide


Andrew Ellis NO6E
Lafayette, CA

 

[evolocomotive]

Honestly, I've been listening to RR for 25+ yrs and I've had several GRE pre amp's and at the end of the day a well built and tuned antenna is just as good as having a GRE pre amp. The "Traintenna" is not that impressive number wise, I'd grab a Laird NMO antenna 5/8's wave, chop the whip and call it a day. You can pick one up on eBay for around 30 bucks. BTW I'm sure you've probably heard me on the radio, I worked the North End sub this morning on 1st. I am dispatcher VLL.

Vic

 

[N2PYS]

Yeah i use the 9 volt battery powered (for mobile or plug in for home use) GRE pre amp with a custom tuned Railroad antenna at my shack where i add about 4DB of gain from the amp,because i don't live far from the tracks and live on one side of G.E.'s Lawrence Park, Locomotive building facility I have a pretty choice listening location for both Trains and Marine because i am about 1 mile from lake Erie.

 

[reconrider8]

So vic do you have a link to one and some instructions on "chopping"? And also do you have an updated train id list i have a list but its saying some of the trains should be running from ma to ny but they are running through Weldon

 

[vascanner]

I think elevation is an important part of listening to VHf signals as well. I have had good results listening o railroad traffic with just a 1/4 wave antenna on top of my truck. It is the same setup that the railroad uses on their trucks. If it is working for them I figure it should work for me.

 

[reconrider8]

i know thats right but on my car i really dont wanna put a mag mount on it and possibly scratch up my paint and i dont want to cut a hole in my roof

 

[n5ims]

So vic do you have a link to one and some instructions on "chopping"?

"Chopping" is what some folks call cutting an antenna down to tune it to frequency. This can't be generalized since the length you need to cut varies depending on what antenna you have. The second link I provided above is the chart for the Larsen NMO150 models shown in that chart (if you have a different antenna you'll need a different chart).

 

[reconrider8]

But do you just cut the top or some how take antenna apart then cut it? Ive never really tried to cut one
.. and also which chart am i looking at for length

 

[evolocomotive]

The whip should come seperate in the pkg, cut the BOTTOM, not the top. I think for 32/32 its around 31 inches.

I dont have a list per say, I keep all the schedules in my head.

 

[n5ims]

But do you just cut the top or some how take antenna apart then cut it? Ive never really tried to cut one
.. and also which chart am i looking at for length

Loosen the allen screws holding the whip onto the coil, pull off whip, cut the whip to length based on the chart, put whip back on coil, tighten the allen screws back.

Which chart should you use? If you have a NMO150B or NMO150C, use the top chart labeled for those antennas. If you have a NMOWB150, use the chart for that series. If you have an antenna not on that page, search Google for the chart for that model (e.g. you have a " Larsen LM150C" use the term "Larsen LM 150 C cut chart"). Other antennas are pre-tuned and there won't be a chart for them so no tuning will be necessary.

It's not really that hard, but remember that you can always cut more off, but can't add back so measure then check, and measure then check again. Verify again that your chart matches your antenna and measure/check again and only cut when you're sure. Some antennas have an optional spring and you'll need to use the chart for the "with spring" values if you use the spring.

 

[reconrider8]

O ok so would a be better or no?

 

[reconrider8]

160 MHz 42 3/4
162 MHz 41 7/8
thats what its saying for the 160 band so would i cut that at like 42" or what?

 

[evolocomotive]

5/8 wave antenna whip cut for 160.590 is 3 ft 7 in. long.

Measure from the top ( where the little ball is) to the bottom and make your cut there.

I cut mine either with a Dremel tool cutoff wheel or a Bolt Cutter.

 

[reconrider8]

thats 43" so thats what i guess ill do. but if i cut it will that mess with the 5/8's wave any? and the 3db gain/ im sorry for all the questions guys but im new a this kind of setup

 

[prcguy]

You can cut any SS whip by making a mild V cut around the whip with the edge of a metal file then snap the two sections apart. A pair of pliers or holding one side in a vise will make the break a bit easier.
prcguy

5/8 wave antenna whip cut for 160.590 is 3 ft 7 in. long.

Measure from the top ( where the little ball is) to the bottom and make your cut there.

I cut mine either with a Dremel tool cutoff wheel or a Bolt Cutter.

 

[W2NJS]

Before you get too excited about cutting the antenna, be advised that for an antenna used for receiving only it's not all that critical. You can cut the antenna you're talking about to anything around 42 or 43 inches and it'll work just fine. Also, for short distance receiving in your local area you can skip the amplifier. The amp will increase the received signal but, as one poster also said, it will also increase the noise you will hear on your receiver.

Cutting an antenna to a specific frequency is only critical when the antenna is also used for transmitting.

 

[N2PYS]

I highly recommend the Dremel Tool over the Bolt Cutters, it's somewhat precision work. If yo locked the keys to your new Rolls Royce your first thought would not be "Thank God there's a Fire house a block away that has the jaws of life and they can just cut the roof off to get my keys" NO it's gonna be "whats the Name of that 24 hour Locksmith Service that Eugene next door was always talking about"

There is time for brute force and time for gentle persuasion!