TRX-2 Front End
- Thread starter RDowson
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From my experience, if the Uniden's are giving you a problem, the TRX will most likely be worse.
Ah, ok. Thanks for the quick response!
Any suggestions which scanner might be better for me to try?
Also might look into the Bluetail Technologies P25RX-II with the multi-mode firmware/software... it has very selective front-end filtering.
Yeah stay away from GRE/Whistler...front end is too hot and will get overloaded. For air band, my old Uniden BC780XLT worked like a champ. Still wish I kept it. Usually you can pick one up fairly cheap on the auction sites.
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- Jan 6, 2009
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I would agree with @nosoup4u and @APX8000 - my TRX-2 is much more susceptible to overload than the Unidens are. However, in rural areas where there is not much RF energy around, then the TRX-2 is pretty sensitive. In larger towns with lots of RF, I have had the Whistler go completely deaf, especially on the VHF-high band where I listen to railroads a good bit.
I have found that adding an external FM-band stop filter on the antenna input helps the Whistler radios reception quite a bit.
- Chris
- Chris
The frequency that I’m having issues with is right in the middle of the AM airband though so I’m not sure if that will help in my situation?
Is there one you could recommend? Can it still scan through saved memory banks?
MStep
Member
As KevinC suggests, you might have to move away from the "consumer" grade scanners to something more like a professional type communications receiver. Perhaps something like the Icom R-8600. But be prepared for some sticker-shock.
Probably worth it if they can resolve my issue. I wonder if there’s a try before you buy option or somewhere that would let me return it if it doesn’t solve my issue.
Well, the FM broadcast band is adjacent to the VHF air band. The TRX radios have a very wide-band front end and do tend to suffer from overload over a broad spectrum if you are in a high RF environment or have a strong nearby transmitter. I have found from experience that the FM trap helps in a number of frequency bands.
- Chris
Ah, I just realized that you are having issues with interference within the VHF air band from a frequency also in the VHF air band. Your are right, the FM trap might not do much for that. A good, sharp notch filter is the best way to approach that problem.
- Chris
That’s the problem I’ve found. A sharp notch filter is virtually impossible to get. I’m looking into a cavity filter but I have no idea how much that’s going to cost.
Ubbe
Member
Cavity notch filters can be very narrow, maybe 1MHz at VHF and costs something like $1000. But they interfere at other frequency bands in UHF and low-VHF so are not a good solution if you scan outside of the VHF band. The best solution for you would be a 1-2 splitter and not scan VHF air on your UBC125XLT and instead use a UBC780 or Pro2006 for VHF air. That Pro2006 are impossible to overload and 780 are almost as good. Both usually go for $100.
That splitter will attenuate 3dB, half the signal, and if that are unacceptable you can use a diplexer or triplexer that have no attenuation and will split up the frequency bands to different outputs.
/Ubbe
That splitter will attenuate 3dB, half the signal, and if that are unacceptable you can use a diplexer or triplexer that have no attenuation and will split up the frequency bands to different outputs.
/Ubbe
Thanks. I have shotgun cable so I can actually run two antennas. One to a Pro2006 and one to my Uniden.
Does the Pro2006 do 8.333 kHz spacing? I’m in the UK so that’s what’s used for VHF here.
Ubbe
Member
It has 5KHz and 12,5Khz and a wide filter +/-9KHz for AM. That makes it possible to receive any 8.33KHz channel. Usually the 8,33 channels that in fact doesn't exactly match 12,5KHz and 25KHz bandplan are found in high altitude levels like 30,000ft where aircrafts transmissions cover a very large area and frequencies cannot be reused as another aircraft in a different part of europe would hear it. Those transmissions are anyhow uninteresting to listen to. Sometimes aircrafts talk to each other at those altitudes using the chit-chat channels like 123.450 that are more interesting to monitor but that then follows the 25KHz bandplan.
Remember that most of the 8,33KHz channels are just a naming of the channels, to match the display on their radio, and they still use the exact frequency from the 25KHz bandplan.
/Ubbe
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