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Railroad/Railfan Monitoring Forum This is the place to discuss monitoring railroad communications.

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Old 07-03-2014, 3:48 PM
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Default NOAA troubles.

Some days I am having some NOAA interference every few minutes for about 1.5 seconds on my CSX feed. The frequency it happens on is 160.470 AAR24. The nearest NOAA tower to me is about 9 miles away, 1000W, and 500ft.... It's frequency is 162.475. The easiest solution is to lock out the affected channel, but I don't want to lose that channel because it is a local shortline railroad. The setup I have is a Diamond CP22e at 25ft tuned to 161mhz, LMR400 feedline about 30 feet long, (radio is upstairs) ARR P160VDG preamplifier, Kenwood TM281A. How can I most efficiently get rid of this?
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Old 07-03-2014, 4:36 PM
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The NOAA weather transmitter is probably overloading your receiver. Start by eliminating the pre-amp. Next step would be to attenuate the incoming signal or reduce the height of the antenna. A more sophisticated, though more costly, approach would be to install a band pass or low pass filter between the antenna and the radio to block out the frequencies above 162 MHz.
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Old 07-24-2014, 1:08 AM
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NOAA sites are just a pain sometimes. When I was chasing UP 3985 a few years ago on Illinois, there was a NOAA site near Chester, Il, that was wreaking havoc on my scanner. When I got within a mile or two, my RS handheld just got completely overloaded on the frequency I was trying to listen to, even with the squelch all the way up!

Most broadband scanners simply don't have the selectivity to be able to keep this from happening.
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Old 07-24-2014, 7:39 AM
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Yeah, I couldn't imagine bow bad it would be if i were using a scanner.
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Old 07-24-2014, 7:43 AM
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I don't want to lower my antenna. It's only 25 feet as it is. And i just bought the preamp to help with coverage of fringe signals, which it does immensely. I wonder if a low pass filter would actually have that hard of an edge being that it's so close in frequency. I'm willing to try, though.
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Old 07-24-2014, 8:21 AM
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Check with PAR filters and see if they can come up with a tight enough notch/edge for you.

PAR Electronics | Filters for the commercial 2 way market, MATV, FM broadcast, laboratory, marine industry, amateur radio, scanner and short wave listening enthusiasts
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Old 07-25-2014, 9:43 PM
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Some time ago, one of our local ham 2m wide area repeaters would key up and broadcast
an ugly audio mix of county fire tone out and NOAA whenever Fire toned out a call.
I was surprised the repeater owners let it go on as long as they did...


So N4RMT, did eliminating the pre-amp solve the problem?
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Old 07-27-2014, 12:18 AM
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For a while I had the exact opposite problem with BNSF freqs hammering the front end of my weather radio. I am really close to the train yard and the signals are hot. Don't have that issue anymore as the newer wx radios seem to handle it without problems. I would be check the weather and hear which train was on track 5.

Last edited by jwilson2013; 07-27-2014 at 12:33 AM..
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Old 07-28-2014, 2:50 PM
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Quote:
Originally Posted by mikepdx View Post


So N4RMT, did eliminating the pre-amp solve the problem?
I haven't eliminated the preamp. Not going to. I just spent 130 dollars on it. Im in search of a filter now.
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Old 07-28-2014, 4:02 PM
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Most of there sites are transmitting between 100 to 330 Watts!!
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Old 07-28-2014, 4:16 PM
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Most NOAA transmitters run at 1kW into the antenna. Your best bet is to look around for a used commercial bandpass cavity filter. The rail and NOAA channels are simply too close together for any cheaper filter to work adequately.
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