When you have the frequency in VFO mode that you want to place into memory,
hit the function key. Then, so as not to overwrite a previous memory
channel, advance the knob one click. Then, press the C key and you should
hear a long beep.
To go to your memory channels, just press the C key. If you program a
channel into memory and hear the long beep, I think you are returned back to
VFO mode, so if you turn the knobby thing, you'll just be changing
frequencies.
Hope my recollection is right, as I don't have the THF-6A in front of me
right now.
Steve
k8sp