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Go with real life over calculated.

I already searched the forums and didn't find the answer I was looking for. I recently purchased an Anytone AT-878UVii and I noticed that the box now states the factory frequency range on the UHF side is from 420-450mhz. I know the earlier units with the same model number were listed on the box from 400-490mhz. Is this the same unit as they were before, and still capable of being opened up to transmit and receive "out of band"? I am thinking the packaging has simply been updated for US sales. Has anyone unlocked a recently manufactured unit with the 420-450mhz range listed on the box? Thank you in advance! -Adam

Where will the Lowband VHF freqs come from? I doubt that the FCC will entertain any proposal at this time and I'm pretty sure that APCO will put up a great fight to keep the Public Safety freqs for Public Safety use for several more years, or maybe a decade or two more, until everyone has migrated off the lowband VHF spectrum. Look how long it took to get the TV Broadcasters off of TV Channels 14-20 for public safety use in the T-Band in the large metropolitan cities/regions throughout the country; and then there was refarming of the UHF spectrum; getting public safety to change to narrowband missions; let alone getting Nextel to give up the 800 MHz spectrum for public safety use after getting public safety to give up the 2.1 GHz spectrum. As the Queen stated, nothing will happen relatively soon and I suspect not less than 10 years, at the minimum.

See my video on the RT-900 in the Equipment Review section on the Forum. At 2M and 70cm I'm able to hit a Repeater on the White Tank Mts. at over 20 Miles away with a 3" antenna from a Suburban Area with trees, houses, etc. I'm sure this radio will work well enough for folks to dip their toe into other Bands to see if they want to invest more in a "Higher End" radio but for me on my tight budget this one will be just fine.

Been wanting something to play on the 6M and 33cm/900MHz bands and found this radio. The Radtel RT-900 will actually do 18MHz to 999MHz when put on "Super Mode" and with the proper antenna tuned for the right frequency just may be the ticket for a low cost HT to mess around on Multi-Bands. Enjoy the video and thanks for watching. TN.Frank Out.

My first two (2-pack kit) were fine (anecdotally, even better reception once I got a couple Nagoya 701g 5.5in antennas for them). I just ordered a third one (plus another Nagoya 5.5in) - here's to hoping..

I applied the Carson bandwidth rule earlier using 2.7 kHz as the upper limit for audio frequency response and 2 kHz as the deviation. That yields a CBR of 9.4 kHz which exceeds the regulatory limit of 8 kHz. Then I stumbled across a discussion about this new Super Narrow Band FM. Another interesting several minutes. But I’m still curious about how the two modes actually measure on test equipment. Ken said that he actually got more usable range from FM. Kirk says that AM will definitely travel further because it’s narrower bandwidth.

The relevant sections are: https://www.law.cornell.edu/cfr/text/47/95.971 https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95/subpart-D/section-95.973 https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95/subpart-D/section-95.975 https://en.wikipedia.org/wiki/Carson_bandwidth_rule

I'm waiting for something to compile so I tried it. 9V batteries are spicier.

... When the price of a handheld radio from [big-box-platform] is less than a three-pack of Don Francisco's coffee now-a-days... licking the handheld's battery leads may be a cheaper pick-me-up in the mornings*. (* prolly' shouldn't try that if my childhood experiences with 9-volt batteries are any indication )

Thanks so much for the replies. Please feel free to point me to any stickies or threads that might teach me more about how this network might degrade my GMRS experience on the higher power channels when transmitting simplex. I am worried now that my investment was bad. Now back to your regularly scheduled FCC Rule discussion...

Unless you're a superbowl-er. Their AM transmissions require the bandwidth of three CB channels.

Someone can't force you to stop transmitting on a specific frequency and using a specific tone. You have every right to use the frequencies as the repeater owners do. The only thing they can do is either change tones, move to a different frequency, or turn the repeater off when they aren't using it. I have been down that path with the FCC and civilly with an attorney. So, I leave my repeaters off when I am not using them due to an unwelcome user.

They don’t. If you have the frequency and input tone (leaving the output tone unprogrammed) you can activate the repeater. Of course you shouldn’t without permission but technically you can. However, there are additional access tones and codes that can be programmed for some repeaters but they’re seldom if ever used in GMRS.

Hello all, I am brand new to GMRS and got one to install in my off roader (along with a license to operate it). I am in the middle of Atlanta GA and have a question about the NGGMRS group that has been referenced in this thread. How do they keep folks from using their repeaters? I ask because it looks like they have a list of all the repeaters, channels on which they TX/RX and the list includes RX and TX tones. Isn't that all you would need? Sorry for the off topic newb question, just trying to understand how this is going to limit my GMRS use.

Thanks for explaining AM to a forum full of radio people. Data showing the actual bandwidth of a CB radio in FM vs. AM, please.

Update: I went to open area yesterday and took Steve's advice. All antennas have a 3+ SWR using the trucked mounted NMO. I connected the magnet base with the unity gain antenna that came with the radio and the SWR was 1.1 and the Ghost had 1.124 SWR. The only thing it could be now is the through hole NMO/cable. I'm going to put a new PL-259 on and if that doesn't work then I'll have to drop the headliner again and install a new mount/cable.

in FM the modulation stays the same it uses all the bandwidth, In AM the amplitude of the carrier wave changes with the instantaneous amplitude of the modulationg signal. AM essentiality uses less bandwidth with more emphasis on the modulating carrier

This was a couple years before there was an NTIA, so unsure. But what's done is done!

That was probably Jack. He has that effect on people. LoL I was with him in the beginning of the project. It was his idea. Mike is the one with the experience. So Mike is driving the proposal. Jack is a nice kid and has good intentions, but he is very abrasive (can't accept being wrong) so it makes it hard to get along with him. Sadly, while I like him, he is the #1 reason I dropped out of the project. Agreed. There is no one solution. Personally, I like the idea because it has potential to do some good for Joe Q. Homeowner who doesn't need an experimental or business class radio license. However, Amateur Radio 80m through 70cm, combined with Satellite and Cellular is the closest thing we can get to having a complete tool kit. I'm pretty sure that is not correct. Everything I can find says that Amateur Radio is the primary assigned service, and the military and other federal agencies are authorized to utilize the 50-54 MHz band in the United States as a secondary or non-interference basis to amateur operations. If there is something different, I would love to see if you can share it with us... I can't find anything. https://www.ntia.gov/files/ntia/Spectrum_Use_Summary_Master-06212010.pdf#:~:text=The military agencies operate radio communication systems,in this band on a non-interference basis. https://www.ntia.gov/sites/default/files/2023-11/4_2021_edition_rev_2023.pdf

Well, no, narrowband FM is typically only 6.25 kHz and the few AM transmitters I’ve used do 6 kHz (up to 4 kHz per sideband on SSB on my ham radio). I would believe data sheets on modern am/fm CB radios if you want to do some research.

You are correct, the signal doesn't travel any farther. It is the inverse, an FM receiver will reject a stronger signal until it is strong enough to "lock on".

When I was at Ft Devens learning the whys and wherefores of ECM/ECCM, we had a window of time to Jam the FM Audio on a local TV station. Using a Dummy Load running 1500w, we would still jam TV sets within a 1 mile radius of the Transmitter (AN/TLQ-17). Lotsa of fun changing the dialog on the Soaps. That and SERE Training were the most fun I had before my PCS.

Authorized, yes. But FM requires all of that bandwidth and AM doesn't.

We got in trouble with the local TV station in Rolla, MO when I was stationed at Ft Leonardwood. We would have the basic trainees tune the PRC77 radios to the TV station and one trainee keyed up the mic. It didn't take long for the TV station to call the post commander's office to complain. We would occasionally upset some sad ham within the 6m band. But as you stated, once we told them whoever we were and that we were the primary users, complaints stopped. The PRC25 and PRC77, along with vehicle mounted radios have a low band (30 - 50 MHz) and a high band (51 - 70 MHZ). The SINCGARS frequency hopping radios use 30 - 88 MHz. The state of Missouri still uses 42, 44, and 46 MHZ for public safety and emergency management. Granted these frequencies are more as a backup system now days. And other states still use the VHF low band also. So that will need to be taken into consideration with the propels to add VHF Low to GMRS or even to amateur radio.