BoxCar

Just because "I saw it on the Internet" doesn't necessarily imply it is correct or complete information. You need to know and understand the source and their agenda in accepting the information as correct. With radios, the allowable frequencies and uses are set by both regulation and treaty. Treaties between countries are important as radio waves do not respect borders so agreements are needed to mesh the use between different purposes as defined by each. As an example, Canada has assigned different uses for some radio frequencies than they are in the US. The treaty allowing some frequencies to be used also blocks others because the frequency is intended for a different use in their country. I

You have two things to understand here. Repeaters are almost always higher power than your hand held (HH). Repeater antennas are almost always higher above ground than your HH antenna. Power means better coverage for the signal area and height means distance. The higher above the average terrain in your area you put an antenna, the greater area served.

More likely the battery is bad from being over discharged as it probably doesn't have a low voltage cutoff.

Yes, they are called SDR (Software Defined Radios) and interface to your computer.

Ahh, another wallet in the wishing well!

Yup, welcome to the zoo!

While there is some truth in what @Socalgmrs sys, the shape of the ground plane isn't as important as it sounds. Your antenna will work fine with a better radiation pattern front and back than to the sides.

Definitely sounds as if it is a configuration issue. Does the repeater use tones? If so, remove the tone on the transmit frequency (462 MHz) and on the handsets receive (also the 462 MHz frequency). Be certain the HH transmit frequency has the same tone as the repeater's receive frequency (467 MHz). Does a HH open the repeater's receiver on the 467 frequency? What antenna is the repeater using? Is the antenna tilted away from your location? That may cause the radiation pattern to be more elevated when using higher power. Try a different antenna with the repeater. Just some thoughts on trying to diagnose the issue.

Talk around is found primarily in digital radios which are not approved under Part 95(E).

The GP9NC highest frequency is 450 MHz while the GP6NC's is 470 MHz. The 6 covers the GMRS frequencies while the GP9 cuts off below GMRS.

Stay with the 6NC.

All the radios have to be on the same channel to reach each other. To monitor and use both a repeater and simplex channels the radio must be capable of dual channel operations. In other words, both an A and B channel.

Welcome- and how deep is your pocket?

You'll need an SMA to SO239 adapter cable. Here's one, but there are many others available. https://www.amazon.com/Superbat-Adapter-Baofeng-Handheld-Antenna/dp/B07FC825HF?ref_=ast_sto_dp

wELCOME - AND IT SOUNDS AS IF YOU HAVE A REAL TREASURE TROVE FROM YOUR GRANDFATHER.

I recommend you program the radio using CHIRP and a computer. As they are then directly connected you don't have to worry about spurious signals messing up the radio.

Where are you testing the SWR? Test it where the coax goes into the antenna to be certain your coax is good. You'll need to use a dummy load in place of the antenna. Also be certain you have the correct SWR/Power meter as the GMRS ones are not designed to work on CB frequencies.

There are a few having a negative offset in the Carolinas where the repeater's input is at the upper portions of the amateur band.

The WCARS repeater W4MOE (146.91, -.6, 91.5) on Mt. Spivey did a wonderful job collecting information and disseminating it. I helped what I could from my location in S. Asheville before leaving because of no electricity or water. My power will be on by midnight Friday, but no word on water. The storm washed out roads and bridges, undermined pipes which caused breakage and damaged the water/sewer treatment plants. Makes me proud that I was able to contribute to the information flow in my little corner of S. Asheville.

We aim to please

The only protocols mentioned in the last expired EXTRA question pool were PACTOR and one other. Nothing about what they were or how they were formatted, just about what equipment was needed.

Don't worry about knowing about DMR or any of the other modes for the ham tests until you reach the Extra level. DMR is not an easy protocol to program as there are 3 elements to sync for every contact you want to use.

The repeater is supposed to be under the owner's control whenever its powered up. The owner would then be able (provided they configured the option) to shut the repeater down and reinitialize it later,

It can also be your microphone. If its an electret (powered) mic, the whine can come from the mic element itself. This sounds like a better scenario as it happens with the engine off.

They were in the Land of Fruits and Nuts. What did you expect? Intelligence?