SteveShannon

I have used OpenGD77 and OpenUV380 many times without any problem finding the right com port. Have you loaded the correct driver for the cable? When you plug in the cable, watch in Device Manager to see which com port is created.

Regulations permit your child to use your GMRS radio including talking on the repeater. Anything other than that would be the personal preferences of the repeater owner. If the repeater is linked to other repeaters you’re stuck hearing the link traffic.

The Diamond SRH999 and SRH940 both include 6 meters.

You’re right. Although a wattmeter might measure an extra few decimal points of outgoing power, it will make zero real difference in range.

The more I think about this I think maybe you’re not really talking about an inverter but rather a 15 amp switch mode power supply, 110 volts AC input and 12.9 volt dc output. Is that correct?

Welcome. Sounds like you’re doing everything right.

It really depends on the design. It probably will still be enough. Just hook it up and see.

Adam, When you use the CPS for the radio there’s one place where you can set the range of the radio. What choices do you see there? That should answer your question.

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.

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.

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.

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.

On CB, FM and AM are authorized to use exactly the same bandwidth: 95.973 CBRS authorized bandwidth. Each CBRS transmitter type must be designed such that the occupied bandwidth does not exceed the authorized bandwidth for the emission type under test. (a) AM and FM. The authorized bandwidth for emission types A3E and F3E is 8 kHz. (b) SSB. The authorized bandwidth for emission types J3E, R3E, and H3E is 4 kHz.

I wasn’t challenging you specifically but the notion in general. Edited to add: Most people think of how far AM broadcasts carry compared to how far FM broadcasts carry, but the major difference between AM and FM broadcasts is frequency. AM broadcasts are Medium Wave, 650 kHz to 1640 kHz. At those frequencies the radio waves are much more likely to skip off the atmosphere. FM broadcasts are VHF and much less susceptible to skip. Also, AM is much narrower in bandwidth which makes it easier to be detected at farther distances. The difference in distance is not a function of modulation type. So, because they are using the same frequencies, AM CB and FM CB should not be greatly different in range.

What would allow an RF signal travel further if it’s AM rather than FM?