SteveShannon

There’s no GMRS community (or GMRS repeaters) here (Butte, MT) but I’m active on 2 meter and 70 cm using a Radioddity DB20G. I am also active on HF using a Yaesu FTDX10 (160-6 meters @ 100 watts), with a short RG213 (HF has far less losses than UHF) running to my SWR/Wattmeter, then a six foot ABR400 jumper to a window pass-thru, which would really be bad in UHF). From the other side of the pass-thru is a 15 foot jumper to the 49:1 unun which is connected to my 66 foot wire which is 30 feet up on a Spiderbeam fiberglass mast. My BS and MS are in Engineering Science with an emphasis on controls, my PE (engineering license) is in electronic engineering but I worked on a section crew for Burlington Northern one summer.

I don’t have a repeater. I’m just a retired engineer and a ham.

https://www.polyphaser.com/2-ft-uhf-to-uhf-m-m-400-series-low-loss-cable-jumper?creative=&keyword=&matchtype=&network=x&device=m&gad=1&gbraid=0AAAAADuUXEAGe1sTFWw7lLUNDWSUXIcEz&gclid=Cj0KCQjwhL6pBhDjARIsAGx8D595HSFQtqWtHdumnNhUeir3UBZn6TIUWo0dQy9Ai3Wpm9FzVL1A7ocaAkCVEALw_wcB

Watch this to see the problem with 90° connectors (except silver plated amphenol ones).

Me

I’m going to go work on my cabin. I’ll check in later. I wouldn’t get too hung up on SWR until you have the cable losses figured out. A dummy load has a perfect SWR. Super lossy system will also result in a very low SWR because the reflected power is so low. So SWR in this case is meaningless. Power measurements at each transition is the real test.

Could be. Could also be the cable construction or too tight of a bend. But losing 30 watts in two feet is an extremely high loss. I would go buy a piece of real LMR400 with good connectors already installed at the very least.

No, possibly just a bad cable. You have 48 watts coming out of the radio. Two feet later you should still see 48 watts, unless it’s a type (what type is it?) that has super high attenuation.

None of the measurements you have provided indicate a problem with the duplexer, but they do indicate extremely high losses in the cables, especially for that length.

Although you told us the brand, you didn’t really say what the actual length and type of the cable, such as KMR400. I really like M&P cables which are made in Italy and ABR cables which are made in the USA and Times-Microwave by MPD which are also made in the USA.

I hope nothing I said made you change your mind.

Some switch-mode power supplies may, with the addition of a few components, be used to keep a battery fully charged with the radio connected to the battery.

A car’s electrical system puts out approximately 13.8 volts while the engine is running. The charging voltage can be somewhat higher, even up to 14+ volts. That drops to about 12.5 when the car is turned off. Mobile radios must be able to accept all of these different voltages, but they are usually optimized for 13.8 volts.

Since you know for sure the CTCSS frequency, push the Menu button and step through the menus until you get to menu 13, which is where you set CTCSS for transmitting. Step through the tones until you get to the right tone. Test it with one of your buddies. Then do the same thing for menu 11 which is CTCSS for receive. This video shows how to set the codes, but it also shows how to setup for a repeater. Just learn about the codes for now.

The problem is that many (most?) of the inexpensive radios have a few extra CTCSS codes. That’s true for both FRS and GMRS. That upsets the numbering. What brand of radios do they use? It sounds like you’re using simplex anyway and the UV5R does have the ability to scan for CTCSS so just do that. In the meantime leave the tone out on the receive side and you’ll still hear your colleagues.

Actually, your idea made a lot of sense. Just put news of pending service outages into the repeater information so it’s available in one place where people can look it up.

Premium membership allows a person to generate repeater access reports that might be what you want.

Premium members have the ability to generate repeater access request reports. You can do them for all your repeaters or specific to a particular repeater and for all statuses or for a status of pending, approved, or denied. Maybe that would help you. I have no idea what information appears in the report or the format.

I’ve only been to one about a few decades ago. My daughters and niece surprised me by paying for me to get an autographed picture of Walter Koenig. There might be something for everyone. Maybe even FRS Star Trek communicators.

Welcome to the forum. Have fun!

Don’t you keep a database of the people you’ve granted access?

I have a friend with a Jackery as well. A Jackery is neat, but a poor substitute for a battery. The car port limits current to 10 amps, which isn't enough for a 50 watt transciever. If you crack it open and hook up an Anderson PowerPole extension, directly to the battery it would be more useful, but a battery in a battery box with Anderson PowerPoles is much more flexible: https://www.dxengineering.com/parts/wmt-58513-1403 Or this one from Gigaparts - it doesn't have PowerPoles but PowerWerx has fittings that might be useful: https://www.gigaparts.com/explorer-deluxe-battery-box.html and the batteries to put in it: https://www.gigaparts.com/p04power-12v-12ah-lifep04-battery.html or https://www.gigaparts.com/po4power-12v-24ah-lifepo4-battery.html Unfortunately both of those batteries are OOS right now, but if you look you should be able to find something similar elsewhere.

So if nothing else changed but the location of the SW102, I’m guessing the two watts difference is just a problem with the sw102, because it is simply not possible for a duplexer to add power. But the real point is that it looks like the most significant losses are happening in your cable, not your duplexer. Your duplexer claims a loss of 1.5 dB. That’s 25% of whatever goes into it, which is probably not unreasonable. If you have 18 watts entering the duplexer you should have roughly 13-14 watts coming out. How long is the cable between your transmitter and the duplexer and what kind of cable is it? That can help us estimate what the losses should be there. Your readings indicate that you lost 30 watts out of 48 watts. That’s 62.5%, or 5/8 of your power, which is 4.25 dB loss. How long is the cable between your duplexer and the antenna? You already said it is LMR400. Is is genuine Times-Microwave LMR400 or one of the many copies?

For all GMRS repeaters the offset is always 5 MHz. You transmit to the repeater 5 MHz higher than you receive.

So that tells me that you’re losing 30 watts in the coax before it even gets to the duplexer. Then miraculously you get 2 watts back in the duplexer. 🫨