MN26-C Radio Compass
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This is actually a modified
example of the Bendix Radio Compass, probably purchased from
a government surplus shop around 1949. The price of a domestic
radio was relatively high after WW2 and anyone with appropriate
skill, such as a radio amateur, would jump at the chance to buy
an MN26C as its frequency coverage enabled it to receive long
wave and medium wave broadcasts with only small modifications.
In 1948 a table model radio would cost around £20, representing
maybe 3 or 4 weeks wages so the prospect of converting a WW2
equipment which cost a mere £4:10:0d
was not to be sneezed at. In fact, later as the price of commercial
sets dropped, and wages improved, government surplus prices dropped
even lower. I should say, the fact that items like the MN26C
were modified has made it possible to actually find one. Other,
very esoteric equipments, are long gone.
That shiny metal plate looks
peculiar and actually hides three preset controls. Because the
dial is marked only 0-100 I suppose one could put a sticky label
on the plate and use this to provide settings for local broadcasts... |
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Above is a view of the
top of the chassis. It looks pretty complete although at some
time it appears to have been dropped and a can at the rear (the
compass output transformer)has become loosened from its base.
Under the screen lower left is a 5-gang tuning condenser... a
very rare thing and a clue to the very high sensitivity of the
equipment. In fact the performance of the receiver made it an
excellent candidate for conversion into a car radio. As I slid
the receiver from its case I expected to see a mains transformer.
This was because it seemed so heavy, but in fact as you can see,
it still relies on an external power supply. What on earth makes
it so heavy as the chassis and most of its parts are made from
aluminium?
Below is a view under the chassis:
I like the ordered layout, especially those regimented decoupling
condensers lined up down the centre. You can always recognise
an American WW2 equipment from its tidy layout. I notice a few
British parts, for example the pair of metal-cased condensers
mounted rear-right of the chassis (these are marked with Air
Ministry codes). In fact the dynamotor is missing. That was used
to generate the HT for the radio and in its place as well as
those two grey condensers is a pair of cans marked ES691025,which
I suspect are smoothing condensers (although a 1953 publication
found in a search of the Net tells me they are BC456 modulation
transformers). |
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Below is an excerpt from
an early document published for experimenters. The original was
a lot clearer but you needed a good magnifying glass to read
the circuit diagram. |
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I'd like to get this old receiver
going when I have time. I'll need to trace the connector wiring
so I can apply HT and LT then check that the phono socket connects
to the audio output transformer then find out what all those
front-panel controls and switches are for... |
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