SteveShannon

Agreed. And actually both excess heat from current and breakdown from excess voltage could both be happening. Even though peak voltage leads peak current by a quarter wave when they leave the transmitter, off peak current or voltage can still combine to exceed specs for the transistors. This is one time where a very lossy transmission line is a benefit!

Welcome to the forums. I can’t answer your questions about the H3 being a good first radio, but there are lots of different posts about them.

Quit lecturing people on “the info you promised you’d read”. The information on the license says absolutely nothing about repeaters and your comment is not helpful to anyone.

That’s the conventional wisdom, but I’m curious what the actual failure mechanism is. Is it an excess of voltage or an excess of current that destroys the finals? We all oversimplify it by talking about “reflected power” but in reality both voltage and current are reflected by an imperfect impedance match. Depending on the length of the transmission line, the reflected voltage or the reflected current will additively combine (constructive interference) at specific locations along the transmission line. If your transmission line is just the right length the voltage (or at a different length the current) will result in twice the value of the peak forward voltage (or current). I anticipate that’s what actually causes the destruction of the finals and why it doesn’t happen to everyone in the absence of foldback protection.

Google the service manual. Most transceivers have a transmit receive relay that connects the transmitter to the antenna and disconnects the receiver from the antenna whenever transmitting. That relay is there to prevent damage to the very sensitive receiver circuits while transmitting. It might be a simple thing to fix.

Less than we typically predict. I have said a few times that an SWR of 2.5 or so wasn’t the kiss of death commonly thought. However, I’ve also attempted to transmit eight blocks down my street on 2 meters at 20 watts, using a Midland MXTA26 antenna, which is strictly a GMRS antenna and has a high SWR (I don’t remember for certain how high now but maybe up around 10:1) at 2 meters and found that I was unable to be heard. One article that I reread from time to time in on the ARRL site has influenced my understanding of high SWR. It purports that reflected power, no matter how high, eventually reflects again at the radio, this time back towards the antenna. Each time a portion is radiated by the antenna and a portion of reflected power bounces back and forth .At the antenna for the second (or third or whatever) a portion reflects again. Each time some of the signal is attenuated in the cable between the radio and antenna, converted to heat rather than RF radiation. With a no loss cable eventually all of the RF is emitted from the antenna, even if the antenna is high SWR. Unfortunately, there’s no such thing as a zero loss cable, but shortness and higher quality help. The best available to a radio operator is to have no cable at all, such as an antenna directly connected to the radio, as in a handheld radio. This (perhaps only in my opinion) is why handheld radios, including cell phones, can get by with SWRs that are up around 5:1 or 6:1. It isn’t really that measuring the SWR of a handheld’s antenna is difficult. It’s that it matters little.

They don’t, unless the radio is transmitting digital data. Ordinarily GMRS radios have removable antennas.

Either the tone, the frequency, the cable, or the antenna is wrong. Can a friend listening on the repeater input frequency hear you transmit?

Are you on the repeater channel on your handheld or one of the simplex channels? They both receive on the same frequency but the repeater channel transmits on a different frequency.

Yes, click on their name, go to their profile, then click on the envelope below their name:

That should be right, but you can always get rid of the R-CTCSS and see if the repeater hears you. That way you’ll hear the repeater response regardless of the tone. The other thing is don’t try to talk from one radio to the repeater to the other radio that’s just a few feet away. The second radio might be overwhelmed by the power of the first radio (called desense).

It’s the input tone to the repeater, so it’s the output (TX) tone from your radio.

Is that 30 watts measured at the radio or at the antenna? What are you using for cable? How long? What antenna are you using? How high is it mounted? What’s the surrounding terrain like? Are you in the middle of vegetation, like a forest? How are you doing the range check?

I’ll send you his address.

Start by listening without a DPL code on the receive side. Understand that not all repeaters have a squelch tail and many will not have people listening at all times. By listening without a code or tone you’ll hear everything. Once you are sure you’re hearing the repeater work on transmitting to the repeater. You must have the right DPL code on your transmitter or the repeater will disregard your transmission. Once you know you are able to transmit to the repeater, then go back and add a tone or code to your receiver to limit what you receive to the repeater.

But easy to do a denial of service.

Every one of those is a repeater. Nets are usually held on repeaters.

Are you asking about that Charlotte 575? Yes, that’s a repeater. See how it has a frequency of 462.575 MHz. That’s where you receive it. Right next to that it says “Input Frequency 467.575 MHz”. That is the frequency that you must transmit to the repeater on. That’s how full duplex repeaters work, they receive on one frequency and simultaneously transmit on another. Receiving and transmitting simultaneously is called “full duplex.” There’s also simplex which means transmitting and receiving at different times on the same frequency. Your handheld radio, if it’s a designed to be a GMRS radio, has a group of repeater channels. Sometimes they’re numbered 23-30, sometimes they’re labeled rp15-rp22 or something like that. They automatically transmit on the repeater input frequency and receive on the repeater output frequency. Tones are used to limit access. They reduce interruptions from people on the same frequency but they don’t offer any security.

Maybe this will help: Or his earlier video about the 805:

Although it’s not the least expensive handheld radio the Wouxun kg805 is a handheld that is both easy to use and performs very well, has an SMA connector antenna, which is standard for most GMRS radios and which allows easy connection to an external antenna. It’s not plagued by a too-busy user interface (in fact some people might want more display). It’s nearly perfect to hand to someone who’s just learning.

You can also fix your typo by clicking on the three dots I. The upper left corner of your post and choosing “Edit”. Small earthquakes maybe, but large ones can be just as devastating as tornadoes or hurricanes. Fortunately it has been a while since we have had one of those here in Montana.

The effect of using the "wrong" antenna can be a big unknown. It's physically impossible to make an antenna that is perfectly tuned for all bands. A GMRS radio will typically have an antenna that's optimized for GMRS frequencies, but works acceptably for other bands. The step size issue will take a radio off frequency though. Often I have had to reduce them less than 25 khz.

A little more about AM versus FM. The ability to hear multiple transmission sources simultaneously on AM carries over to natural noise, such as static and lightning. There's always something to hear on AM, even if it's nothing you want.

There's no such thing as a free gun show.

I disagreed with you even before you wrote that. Here's a link to a post from yesterday: