Talkback mods or radios that already had that feature was never established back when I was servicing radios as a business. If people wanted to test their mic, many just plugged a speaker into the PA jack and turned their mic gain down. As for adjusting the echo, the PA would be good for that also, although echo boxes were very expensive and therefore rare during my time. Of course simply using a PA speaker would never work nowadays for those that want to hear themselves continuously. As a true audio representation, I never really liked the PA test either. It’s just a quick and dirty test. Like today’s talkback feature, it’s only representing the audio before it goes into the RF stage. I compare it to sampling the output of a stereo preamp before it goes into possibly a power amp that has serious problems, then afterwards calling it good to go. Those that think their talkback audio is the same as what others are hearing over the air are only being deceived. I find that too many think that it is. Close enough for practicality, possibly, but I’m hesitant to place it into the horseshoes and grenades category. I’ll let the scope with an RF probe be the judge of that.
