This is quite a rare find. The
receiver is part of a set of equipment used by the Fleet Air
Arm mainly during WW2 and fitted in various aircraft (although
I've only found a record of it being used in the Fairey Firefly,
Fairey Barracuda and perhaps the Sunderland) to cover transmission
and reception across the long and shortwave bands. This Type
76 receiver covers the former band, whilst the Type 78 covers
short waves. The setup was referred to as "Four Square"
after the shape of the rack and its contents, comprising pairs
of receivers and transmitters Types 76/51 and 78/53. It's around
the same vintage as the R1155 and post-dates
the earlier R1116. As you can see below
the case is made from aluminium and has suffered from being stored
under damp conditions. Hopefully it'll respond to cleaning up
and a re-spray. The "26V" refers to the voltage on
which the system was designed to run (via a DC-DC motor converter)
and is also the voltage used to run the valve heaters which are
wired in series. Because this set didn't cover an amateur band
it's not as common as the shortwave model.
The equipment was covered by document
ARI5206, and the circuit diagram, kindly supplied by
Andy Young, M0FYA, can be seen below. There's a similar sized
and very famous US receiver, the BC453 known as the "Q5er"
by radio hams (and used by many as an IF amplifier) which is
roughly similar in size and function to the Type 76 receiver.
The BC453 also has a matching transmitter. Our local government
surplus shop, Super Radio, in Liverpool always had a BC453 sitting
on the counter, tuned to the Light Programme on 200Kc/s. I imagine
this was either to keep the sales assistants from falling asleep
when not very busy, or to publicise the fact that they had some
for sale. I'm sure Liverpudlian radio enthusiasts, now pensioners,
will remember this.