Below is a collection of pictures
of the set
You'll see about as many gear wheels
as valves. I counted 16 valves (one is hidden away on tthe main
The receiver tunes 24 pre-set channels
in three bands viz.
2.8 to 5.2MHz, 5.2 to 9.7MHz
and 9.7 to 18.1MHz
Using plug-in crystals in the ranges
corresponding to the three bands viz.
4.95 to 7.35MHz, 7.35 to 11.86MHz and
7.55 to 15.95MHz.
The receiver is a double-conversion
superhet and the RF design follows standard practice but the
set has a main chassis and front panel plus seven detachable
modules. Remote control facilities are fitted which use electric
motors. The first IF is 2.15MHz and the second IF is 100KHz.
Although crystal controlled the 2nd oscillator can be tuned plus
or minus 7KHz so this might be a good place to start if a wider
tuning range was to be required?
There's broad filter for R/T, and a
narrow band filter together with a BFO set to 99KHz is provided
for CW reception.
The RF amplifying unit uses 6 valves
V1 CV140 limiter, V2 CV454 1st RF amp,
V3 CV454 2nd RF amp, V4 CV453 1st mixer, V5 CV454 IF amp, V6
CV453 2nd mixer
The IF amplifier uses 9 valves
V1 CV138 2nd oscillator, V2 1st 100KHz
IF amp, V3 2nd 100KHx IF amp, V4 CV138 cathode follower, V5 CV140
Audio detector & AGC detector, V6 CV138 BFO, V7 CV138 AF
amp, V8 CV136 Audio output, V9 CV140 noise limiter
The main chassis has a single valve
V1 CV455 1st local oscillator.
Below, I've interspersed circuit diagrams
of the receiver as follows:
Unit 4207 Receiver front end; Unit 4208
Receiver back end; Unit 4211 Receiver crystal selector unit,
band switching etc;; Unit 4190 Control unit.