So, for a channel-selector type radio with 10 kHz channel steps only, leaving the radio stock will produce a radio with a random transmit frequency. The trimpot inside the radio can be set only so close to being perfectly on frequency. A two-way conversation is no problem. You just tune each other in with your receive-only clarifiers.
But as soon as a third party tries to join the conversation he'll be twisting his clarifier back and forth each time a different station keys up.
This is what would prompt the old-time "SSB club" guys to run you off of "their" channel if your radio was "stuck" on the wrong transmit frequency. You would be greeted with cries of "Get your radio fixed, and come back then". The alternative was for everyone on the channel to "re-clarify" to YOUR transmit frequency. Never heard those guys volunteer to do that.
The ability to line up four or five stations all on the same transmit frequency is no trick with a VFO-controlled ham radio. But to do it with a channel-selector type radio, you need to unlock the clarifier.
I prefer to call it "locking" the clarifier's transmit frequency to the receiver frequency. A stock legal 40-channel SSB radio is "unlocked" in this sense.
Yeah, semantics.
Bottom line, if you carry on a conversation with more than one station on the same frequency, life is simpler if you don't have to twist a fine-tune knob separately each time a different station keys up.
And if you have a radio that tunes in 1/10-kHz steps, just select a frequency that sounds best with the receive-only clarifier at 12 o'clock. Most SSB operators don't seem to get much closer than 100 Hz to start with. No point to "unlocking" the receive-only fine-tune on a radio like a 2950 where you can tune in 100-Hz steps.
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