RA117 serial number N0489 (/cont)

VFO2 is precicely that. Unlike in the RA17 and 17L where the box also contained the third mixer, in the RA117 it is simply just the second VFO. It is however a completely different animal. Without the need for the tunable (2-3MHz) band-pass filter, the unit is considerably smaller, and lighter. In the RA17 and 17L, the second VFO is an EF91 and tunes from 2.1MHz to 3.1MHz. In the RA117, the second VFO is one half of a 12AT7 double triode and tunes from 3.6MHz to 4.6MHz.

Provision is also made for selecting an external local oscillator.

This is a relatively easy unit to work on. Even removing it from the main chassis is easy. On the RA17 and 17L, in order to remove the unit it is first necessary to remove the lid of the module simply to gain access to one of the two long screws which secure it to the chassis (there is a third, short screw also). However, Racal obviously realised that this was poor design and replaced this ‘hidden’ screw with one which comes up from underneath, with the tapped thread being in the VFO casting as opposed to the main chassis.

The additional capacitor on the left in the lower photograph is a 47nF capacitor across the heater supply. This features in later models of the type.

Again, it is wise to test this unit prior to re-installing.