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Yep, I can certainly vouch for that. Since putting a super high gain antenna high up, the analyzer was reading a massive noise threshold.... needed 2 cans (cavities) to bring it down to an "acceptable" level. I think the radio range these days, aside from more TX power, is also limited by receiver being overloaded by RF noise; b/c after finding out the noise threshold at my location I was blown away how high it was... so if you don't have a radio that has a tight front end you won't receive signals from very far... Don't sell yourself short, Marc, you are being helpful to others, and nobody knows everything.... point is that sometimes little tidbits like that are the eureka moment that makes it, even for knowledgeable ppl. G.

While I agree with you... my comments are generalized. People with HT's and mobile radios aren't going to walk/drive around with massive tuning cans and massive narrow resonance antennas for improved noise filtering. Also... a hug majority of complaining and questions I see/hear is "I can't reach a repeater" and "how do I get more range out of my radio?" Most people building repeaters are likely educated and experienced enough that the don't need my advice.

Not entirely true. Your transmit coverage will always look better when you model a higher elevation, even at lower power... BUT... at some point, the repeater is just part of a System, and any repeater system that does not receive as well as it transmits, is mostly a one-way paging transmitter. If you want the mobile/portable users to talk back in, then having a clear and clean receive frequency matters, and having a well tuned receiver matters. If I stick your receive antenna high in the sky, the good news is that you might hear transmitters 100 miles away. The bad news is, you're going to hear stuff 100 miles away that wasn't part of your system, and if those transmitters interfere with your ability to receive desired transmissions, then you're back to having a deaf System.

Yeah, being within that distance of a broadcaster is the real problem at hand. Based on your symptoms, I'm assuming there's UHF TV broadcast on that tower in the 500 MHz band (which is almost all that's left of UHF TV). TV typically runs tens to hundreds of kilowatts, and any internal or external mixing products of TV broadcast may resemble noise due to the DTV modulation. FM is more easily controlled and the harmonics aren't in-band (fourth harmonic ends at 432.2 MHz), but that still requires strong filtering. To do an actual check of your RF environment and noise floor, you'd need a good spectrum analyzer that stays linear up to at least 10dBm; most quality equipment is rated up to +30dBm. If you've got noise that appears to be in-band but cavity filters improve the situation, you've probably got intermod going on. Band-reject filters near the antenna can help with that. If filtering near the receiver doesn't improve in-band performance to a satisfactory level, PIM may be at play. Right now, intermod and overload effects could mask a generally crap noise floor from unintentional radiators; don't expect to dive in with hundreds of dollars of equipment and hit thermal noise floor (though you'll have to spend a little bit more to avoid PIM and ensure linearity of any active components). A noise power of -125dBm/16 kHz is pretty typical for a quiet area, compared to thermal noise floor at -131dBm/16 kHz. HDMI/DVI are particularly egregious noisemakers on UHF LMR bands, especially with AliExpress-quality cables. LMR-400 would make a mess of your RF environment. Overload effects don't cause CCRs to not be heard, it simply knocks out their ability to hear. Any RDA1846 design will show desense on almost any rooftop antenna anyways; they're meant to be used with unity-gain antennas attached to the unit and work rather well in that scenario. Desense on the stock antenna or equivalent is only encountered in rather exceptional RF environments.

I understand that, and that is good, b/c living in this kind of area sucks for radio comms. G.

Thank you for the kudos... much appreciated, my friend.

Its not the tone/CTSS creating the potential issues you mention, it's stupid people that are too lazy to invest 3 minutes of their life to read the directions and learn/understand how their equipment works that are the problem..