Lscott

I have the version that does all the digital modes, TDMA and FDMA. The amps were reviewed here: https://www.miklor.com/COM/Review_DMR-Amps.php The amp output falls off significantly on GMRS. I haven’t tested it with a wattmeter yet, however on the Ham 70cm band it draws about 5 amps on my bench DC power supply. On GMRS it only draws 3 amps. That suggests the output is only 60% of the “expected” 40 watts, basically 24 watts of output. If you have no other options than using an amp with an HT I guess you’re sort of stuck. However if you can, for the $100 the amp costs, I would just invest it in a quality higher power mobile radio.

That is a pain. However the few Kenwood NX-1300DUK5 radios I have allow me to assign a different radio ID per zone, and the radio can have up-to 128 zones. I can have different ID’s all dependent on what I need to do. The radios I have are the 400-470MHz band split. I can program in Ham repeaters in their own zones with my registered Ham DMR ID, and Part 90 frequencies, if necessary, with different ID’s in other zones without having to reprogram the radio. Very convenient. I haven’t run across another manufacturer’s models, outside of the new Kenwood ones, that allow this. Likely they exist, just I have seen any.

I’ve posted this a few times before. GMRS Digital Voice - 20221011.pdf

This topic comes up with regularly.

Leave it. Not worth the hernia trying to load it up.

Two big ones Eliminate the elitist attitude too many of the old hams have regarding those with a Tech Class License. There are Hams out there that won't even respond to a call that is a Tech Class. WTF? Same goes for Morse Code. There are those out there that remark, often, you're not a "Real Ham" unless you can pound out CW at 50 WPM. Sad.

I think most of us in engineering have had a professor like that at one point. It's not the wasted time copying down the worthless material I hated. It was suffering with writer's cramp doing it.

Can you spot the error in one of the formulas?

It's very difficult to do and get good results. The reason is the human body is part of the antenna system due to capacitive coupling between the radio's body and the users hand. I've tried it myself and discovered just how hard it is. Even a relative comparison between antennas isn't that easy either. Antenna Testing W9MDB.pdf HT-Antenna-Testing.pdf

A smart licensed operator and a properly tune antenna.

When I lived in an apartment years ago I had my Kenwood Ham HT modified. That allowed the reception of the common 900MHz cordless phones at the time. I picked various phone conversations but it wasn’t any good. Just about every one in range was from the Middle East speaking their native language. Rather pointless and boring to try scanning anymore.

Radio Shack sold such a radio back in the day. The guts of the radio was in the magnetic base, to comply with the fixed antenna rule. The controls were in a remote speaker mic that was run into the passenger compartment.

https://www.goodreads.com/quotes/14977-i-know-not-with-what-weapons-world-war-iii-will

Magnet mounts on 6M and HF don’t couple very well to the body of the vehicle. The cable ends up being part of the ground plane. On a 1/4 wave 6M antenna I ended up using a ferrite toroid near the magnet mount base to decouple the antenna. Otherwise moving the coax around resulted in significant SWR changes. I also paid a few bucks, at a flea market, for some magnet mount CB antennas, Little Wilson, with the idea of cutting them down for 10M. Finally gave up since the bandwidth was very narrow and the SWR jumped around every time I moved the coax a bit while adjusting the antenna.

If you kept your peanuts at least you can eat those.

For a one shot arbitrary pulse shape you can use the Fourier Transform to calculate the spectra. In a prior post I had a link for a paper that had the mathematical model for a nuke EMP for reference and testing purposes. The transform can be used to calculate the spectra. From that the parameters for shielding can be formulated. https://en.wikipedia.org/wiki/Fourier_transform

Or are, but just don’t work.

Another reason why many of the CCR’s, cheap Chinese radios, get a bad reputation.

That only works if you’re wearing a blue uniform with a shinny badge on it. Also it should be one of those huge leather Batman type utility belts with those hand restraints. Gives them crazy ideas.

I don’t agree with how he tests it at the end with a meter. It’s says nothing about the electrical connection. But the idea looks sound. My concern is tipping the can over and having something rip through the foil.

I don’t think that’s a good way to make one. You do need to use metal tape on all of the seams. Any break will allow leakage into the container. That also applies to the bottom too since that most likely is just crimped on with a small gap. Better than metal tape is use a small torch and solder along all the seams. Another poster mentioned a nested cage for the inner one must be isolated from the outer one. In the video that’s not the case. Not only that but the top of the inner cage is missing. I think if the outer bucket was prepared correctly that’s a good start. Then install an insulated liner. A second bucket prepared like the first is where you place your electronics. That bucket then fits into the first. Now you should have a good DIY double Faraday cage.

I purchased one of these simply because Kenwood doesn’t have one and looks like they have no interest in doing it either. I wanted a DMR radio. https://www.bridgecomsystems.com/products/anytone-at-d578uviii-plus-tri-band-amateur-dmr-mobile-radio

That’s what generally foils the whole idea not to mention repeaters, including cross-band types, are prohibited in MURS. A variation of the cross-band idea is an in-band spilt frequency operation. Many radios can be programmed to receive on one frequency and transmit on another within the same band using an arbitrarily frequency offset. The idea would require the GMRS user to transmit on a legal GMRS frequency and receive on a frequency in the Ham 70cm band. The Ham radio user would then transmit on a legal 70cm simplex frequency, which is programmed into the above GMRS radio for receive only, and receive on the GMRS transmit frequency programmed in the GMRS radio. Nether radio requires modifications nor dual band operation. Just the ability to program in spilt UHF frequencies with an arbitrarily offset. This operation in not legal either for the prior mentioned rules. The Ham station shall only contact other stations in the Amateur service. Also it could fall under the general prohibition to engage in one-way communications since the other station is NOT in the Amateur service. I wanted to point this scenario out before somebody dreams this case up and tries a convoluted argument this would pass under the rules. It won’t.

As a Ham you’re limited to ONLY making contact with other stations which are licensed and operating in the amateur service of the US, or of the country the station is located in. Obviously GMRS is NOT a Part 97 service. As a Ham you should know this. I would recommend you get a copy of Part 97 rules and throughly read it. It’s pointless to waste time on something you can easy research yourself.

The reason it’s done is the elimination of the heavy, bulky and expensive cavity filters required for an in-band repeater. This applies to analog radios. The filters are required because the RX and TX frequencies are close together. Without sufficient isolation the transmitter will overload the receiver such that it effectively become deaf. Remember the receiver is feeding every it hears to the transmitter at the same time. A cross-band repeater the frequencies are space far enough apart that a far simpler and cheaper filter can provide the isolated required.