On 03/03/2018 12:46 AM, Chuck Guzis via cctalk wrote:
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".
I think the British considered it top secret in about 1939,
but they knew if they did air raids over France or Germany,
that eventually a plane with one would get shot down and a
magnetron would be obtained in relatively good shape. So,
likely by 1942 it was considered to no longer be a secret.