radar history

[steven at malikoff.com]

Chuck reckoned
> I dunno about these historical accounts.
> I was watching a PBS program about RADAR and the magnetron was made out
> to be a super-secret device, yet there's a clear explanation of it in my
> 1942 "Radio Handbook".

Yeah I know this off-topic, but what the heck.
The Buderi book mentioned is a great account of the MIT Rad Lab story, ie radar from an american
perspective. I have it on my bookshelf and I'd recommend it to anyone.

I also have a book 'RADAR How it all began' by Jim Brown, one of the designers of the Chain Home
system working for the Valve Lab of Metropolitan Vickers, who built and ran the CH hardware from 1937.

Apart from being a incredibly precise recollection of the engineering ("The valve consisted
of a solid copper block about 6 in x 6 in x 4in. ... The 6 in x 6 in faces were machined out
about 4 1/2 in diameteer and grooved to take two ceramic tubular insulators which were about
4 in outside diameter and 4 in long  and 3/4 in thick. On the end of each insulator was the
anode which was a copper plate 1/2 in thick ...." etc etc etc and the whole book is to that
level of detail) it has an interesting and ironic factoid.

The Chain Home 60kW tetrode transmitter tubes were enclosed in boxes about 8 feet high, 8 feet
wide and 8 feet long made from brass sheet and brass angle. To adjust the tubes externally required
an insulator chosen from the allowed group of materials of pure mica, ceramics, steatite (soapstone),
Pyrex glass and a substance called Calit.
Calit was a white marble-like material that could be ground to shape and drilled, and so was chosen.
It was also imported from Germany :)