A pair of R107 receivers
The top receiver is basically
original but the lower one has received, what in the 1950s and
60s would have been normal de-militarisation for its use as a
general coverage set for a short wave listener.
Nowadays a collector of such
things will demand an original example, restored to the condition
as it would have been in the 1940s.
Weighing in at 96 pounds the
R107 would have been used in a fixed station or a heavy vehicle.
Coupled with a 52 transmitter it could have been used for networks
containing the portable Wireless Set No.18 or those used in tanks,
Wireless Set No 19.
Frequency coverage is 1.2Mc/s
to 17.5Mc/s in three bands
The valve line-up...
RF stage, ARP34 (EF39), mixer
ARP34 (EF39), local oscillator AR21 (EBC33), two IF amplifiers
ARP34 (EF39), audio amplifier AR21 (EBC33), BFO AR21 (EBC33)
and audio output AR21 (EBC33), rectifier 6X5G
Power was supplied from AC mains
or a 12 volt battery through its built-in vibrator.
As if the weight of these things
wasn't already enough there is a steel lid that fits over the
front, keeping the effect of bullets and the like to a minimum.
Usefully a complete circuit diagram is glued in place over the
inside surface. Maybe this is the first set where real thought
went into servicing in the field, as not only is there a circuit
diagram supplied but the valve complement has been limited to
only two types (excluding the rectifier) thus dramatically improving
logistics. First level fault-finding could be to merely switch
a couple of valves around.
The most sought after examples
of the R107 have a front cover and one of mine has a rather rusty
example whose inside surface carrying the circuit diagram is