On 12/08/14 17:28, shadow@shadowgard.com wrote:
> The US invented the magnetron tbe (you've got one in your microwave).
>
> The Brits couldn't manage to make a working unit from the info the
> Yanks sent over. The Yanks sent over working tubes. They worked. Then
> the Brits disassembled them (they were bolted together) to make sure
> that parts matched. They did. But upon reassembly they didn't work.

An apocryphal tale, unfortunately.  The world's first working cavity
magnetron was constructed by Sir John Randall and Harry Boot at
Birmingham University in the UK as part of project to produce
centrimetric gunlaying radar for the Royal Navy.  It was first switched
on on 21st February, 1940 and was sealed, not by bolting two halves
together, but by two British halfpennies held in place with sealing wax.
  Later, improved versions were sealed using a gold fusion technique and
were water cooled while the later NT98 design was air cooled, first
operated on 29th June 1940 and giving a pulse output of 10kW at 10cm.
GEC made several copies of this - reputedly using the chamber from a
Colt revolver as a drilling jig - and it was number 12 of this version
that was taken to the USA in August 1940 with the Tizard mission.  It
was later described by the Americans as 'the most valuable cargo ever to
reach these shores.'

And before anyone wonders at my knowledge in a field so widely at
variance with my training - I just happened to be reading all about it
last night :-)

David Shaw