MN26-C Radio Compass


 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...


 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).


 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.


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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