[Sideband]

Originally Posted by Vectamart

I have a System 4 manual but the board featured is quite different to the one fitted in my set.

Thanks in advance.

There are a few variants for the tuning system. One is TRDIV(Tuning Remote Digital)
and VST (Voltage Synthesis Tuning). There may have been a simple TRD as well. TRD didn't use a back-up battery (as mentioned in the above post), VST did.