But what is it?
My guess is that it was either
used in conjunction with a trench set spark receiver or to aid
listening-in to enemy telephone communications.
Two pairs of input terminals
are provided, being marked "HF" and "LF",
with two sets of terminals for headphones
The volume (or gain) was changed
by varying the filament voltage and the tapping on the input
Was it used to amplify British
transmissions or those of the Germans? Click
to see some details of this?
The panel, alas is now just
as you see it. Probably sold as war-surplus around 1920, it has
been stripped of its tuning coils, LT and HT switches, and wiring
(and of course the valve). Why the double military arrowheads?
Ian Gallimore in Toronto tells me that the double arrowhead indicates
the panel was sold as off as surplus.
up in GM'land kindly provided the following....
"It is one of a batch of
1250 listed as Amplifier C Mark IV and IV* made by Newton and
Wright between August 1918 and March 1920 at a cost of £14.25
(£14 5/-) each, or about £260 in today's money.
I attach a description
dated 1921 and a circuit - sorry
the quality is a bit poor but the paper has oxidised considerably,
despite being kept in the National Archive! Below are better
pictures converted from the above.
It was supplied as part of the following stations:
W.T. Set, Light Motor Mk I, I*, Spark, 1.5KW
120W CW Set in Crossley Car
500W CW Set in Motor Car
60W CW Set
CW Receiver Mark IV
From what I can make out, it's purpose was either as an AF Amp
feeding headphones (switch in LF position) or as a detector and
AF Amp (switch in HF position). When detecting, the first valve
(they were all type R) seems to have been fed from a mixture
of signal and BFO. At least, that's how I would translate the
I've put it down as "perhaps
restorable", given a wooden case, some valves, a couple
of switches and a few coils?