Racal MA161 Receiver Fine Tuning Unit
 

Just to keep a track for future reference, we have just ascertained
that the RACAL MA161 is a fine tuning unit for the RA117 receiver. It
works as an external (variable) Local Oscillator in substitution of an
internal 1700 KHz crystal for the mixer between the 1600 KHz IF ant
100 KHz IF, thus allowing for fine tuning.
Thanks to all who helped.
Antonio I8IOV