I have one Tentech made way back when.  I forget what radios it worked 
with.  It used the speech plus calculator board.  Think I paid over $300 
for it at the time.  I had a tentech radio back then.  It is in a box back 
in Kansas somewhere--not the radio, the counter.   It plugged into the 
external vfo socket as I recall.  I'm coming up on 40 years as a licensed 
ham, not counting my novice ticket back in 61.  I've sure had a lot of 
radios over those years.
73s
Butch Bussen
wa0vjr