Racal SA.97 Wobbulator page 4

The underside of the SA.97. The top half is clearly the PSU. There are two transformers and one choke. The metal rectifier serves to provide a negative voltage to complement the output of the 5V4G. This is necessary for symmetrical drive to each pair of deflector plates. Although not clear from the photograph, there are two EHT rectifiers (long thin Tufnol tubes). These provide -2KV and +2KV. The +2KV is purely for the post-deflection accelerator. The circuitry running across the centre is the Y-amplifier and -250V stabiliser circuit.

Across the bottom, left to right is the Timebase generator, +250V stabiliser circuit and +210V Stabiliser circuit.

The frequency marker pulses are ‘merged’ with the fly-back suppression signal which is connected to the grid of the CRT via the large (new 100nF/2KV) white capacitor.