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Railroad Base Antenna Recommendations

Joined
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In the 'patch
#23
Oh, no denying the service life of the Comprod, Sinclair, or Telwave dipoles are longer cause they're better through tough conditions. But again, my statement is just to my experiences. SSM's has always performed better for me at various sites in varying terrain.
Throw one up on a 9000’+ mountain that gets 20+’ of snow and ice.

In places like the mountains of BC, Yukon and Alaska a SSM just wont survive with out being in a comshell.

Even a 210-C4 heavy duty dipole arrays will get bent under the ice/snow loads on mountain tops in western Canada. Usually though you would use only a 1 or 2 element for greater vertical beam width to cover into the valley bottom.

One site near where I grew up, a 4’ Comet hammy dualband fibreglass antenna did not even last one winter. All that was left was the mount on the repeater vault(no tower, the top of the vault was in excess of 1 wave length @ 136MHz) Sheared clean off due to ice. The 1/4 UHF and VHF mobile antennas on L-brackets did how ever, survive.


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#24
Could be your Superstationmaster had downtilt and the dipoles did not? The last Superstationmaster I helped swap out was for the USCG, it was the second one trashed by lightning within just a few years. We replaced it with an exposed dipole array and I think it was a Sinclair. I don't expect any more lightning damage.

Oh, no denying the service life of the Comprod, Sinclair, or Telwave dipoles are longer cause they're better through tough conditions. But again, my statement is just to my experiences. SSM's have always performed better for me at various sites in varying terrain.
 
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#26
Could be your Superstationmaster had downtilt and the dipoles did not? The last Superstationmaster I helped swap out was for the USCG, it was the second one trashed by lightning within just a few years. We replaced it with an exposed dipole array and I think it was a Sinclair. I don't expect any more lightning damage.
DC ground, R56, polyphasers and proper lightning mitigation for the win. Anywhere that has lots of lightning, you are just asking for issues using collinear antennas.

Exposed dipole arrays have numerous advantages over collinear antennas.

I have a friend that has a 5/8 over 5/8 wave hammy antenna that a single 1/2 wave spaced 0dBd gain 210-C1 dipole out performs, mounted on the top of the same wooden pole in relatively flat prairie terrain.


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Point Nemo.
#28
I have a friend that has a 5/8 over 5/8 wave hammy antenna that a single 1/2 wave spaced 0dBd gain 210-C1 dipole out performs, mounted on the top of the same wooden pole in relatively flat prairie terrain.
I've replaced a few of those hammy antennas for UHF stuff. I think it was a diamond. Wrong antenna for the location. A single bay Telewave outperformed it greatly. End user was extremely happy to have a functional repeater after the antenna swap.


As for the MFJ….
Amateurs have some odd ideas of what makes good antenna.
 

W9BU

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#29
Folks, I think the OP has gotten several valid responses to his question. I'm not sure there is much to be gained from the back-and-forth as to which antenna is better for applications that the OP didn't ask about.

I assume that the OP is looking for antenna to put up at his home to improve his railroad monitoring. That's a much less demanding application than a mountaintop repeater. And, as you all know, there's a lot more to an effective antenna installation than just the antenna.
 

nickwilson159

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#30
This thread has been pretty informative. My "temporary" apartment railroad monitoring setup has turned into a permanent setup since other prospective sites fell through, and is currently using a Comtelco 5/8 wave on a Larsen NMO ground plane kit (along with an ARR preamp connected to a Kenwood NX-700). I went ahead and purchased a Sinclair SD210-SF2P2SNM to replace it - we'll see how much of a difference it makes.
 
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#31
That sinclair antenna are a folded 1/2 wave dipole and a 5/8 probably have more gain.
I looked at the ARR website and it's probably the P30-1000/11VD pre-amp you're using but that has a noise figure of 3.5NF.
If you use another low-noise pre-amp with 0,5dB NF you magicly gain 3dB in reception. Most receiver doesn't like too much gain so add a variable attenuator to set the exact level where the gain is max without de-sensing the receiver.
PGA103+ Ultra Low Noise Wideband LNA preamplifier RTL SDR HAM Radio | eBay
Konig Variable Satellite Signal Reducer Attenuator 0-20dB 5055377500313 | eBay

/Ubbe
 
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#32
Is the Sinclair on a metal mast? If so its basically a two element beam and will have a little gain over about 120deg azimuth. I agree on a preamp possibly overloading a handheld radio. I would add a 6dB attentuator after the preamp to reduce gain a bit and in the end I don't think the preamp will improve reception in this case.



This thread has been pretty informative. My "temporary" apartment railroad monitoring setup has turned into a permanent setup since other prospective sites fell through, and is currently using a Comtelco 5/8 wave on a Larsen NMO ground plane kit (along with an ARR preamp connected to a Kenwood NX-700). I went ahead and purchased a Sinclair SD210-SF2P2SNM to replace it - we'll see how much of a difference it makes.
 
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#33
Pre-amps always improve reception for me when I install it directly to the scanner, very much like the ones you can buy as a complete kit, Jim M75 Pre-Amplifier | Scanner Master as scanners usually have bad noise fugures in the 5-6dB NF range and pre-amps with lower NF will improve reception the same amount of difference in dB. It should be sufficient with a total gain of 6dB from a pre-amp but when I have a FM broadcast filter in line I can use the full gain of 15-20dB and have improved reception of 70Mhz and 120MHz with a Uniden BCT15 compared to a 6dB total gain. That's why I recommend a variable attenuater and not a fixed one as it is easier to quickly tune to see what the result will be.

/Ubbe
 

nickwilson159

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#35
Is the Sinclair on a metal mast? If so its basically a two element beam and will have a little gain over about 120deg azimuth. I agree on a preamp possibly overloading a handheld radio. I would add a 6dB attentuator after the preamp to reduce gain a bit and in the end I don't think the preamp will improve reception in this case.
The preamp is an ARR GaAsFET model tuned to 161 MHz with a 0.5 dB noise figure and 24 dB gain. I have a variable attenuator after it that's set for 18 dB for about 6 dB gain overall, which is what Motorola and plenty of people wiser than me have said is the realistic maximum; I did play around with it, but 6 dB does indeed seem to be the sweet spot where there is a noticeable improvement without all transmissions being blown out. It's attached to a Kenwood NX-700, which is a commercial mobile NXDN radio widely used by the railroad industry; they are also notoriously deaf compared to their analog predecessors (and yes, I did have it aligned by a professional shop).

Moving on to the Sinclair folded dipole, I have it hooked up to an MCS2000 currently, and it is performing much better than my other setup. Transmissions that are weak on the old setup are full quieting on the new one, and on the fringes the new setup picks up transmissions clearly that the old setup doesn't even unmute for. It's made a believer out of me for these Sinclair dipoles.

Next step is adding the preamp, attenuator, and some filters (Sinclair bandpass cans & Telewave notch cans) to see if I can boost it a little more.
 
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