Reg Edawds, G4FGQ wrote:
"R&B`s cavity magnetron was developed at Birmingham University in the
midst of the air raids on that industrial city."

Prior to Randall & Boot, magnetrons were low-power devices, outclassed
ny klystrons. R & B`s resonant-cavity magnetron, operating at 10 cm
exuded 100x more power than previous magnetrons and allowed smaller
hardware and imptoved image definition.. The 6 KW GEC manufactured
version given to the U.S. in August 1940 was shipped by ordinary parcel
post to arouse no suspicion of its importance. It has been called the
most important shipment ever to arrive on U.S. shores.

The resonant-cavity magnetron was an awesome contribution to victory in
WW-2 against both Germany and Japan. Their radar development lagged far
behind.

My ship in WW-2 had only one spare part kept in the captain`s safe, the
Raytheon resonant-cavity magnetron for our Raytheon navigational radar
system. Fortunately, we never needed to replace it.

After WW-2, Rayrheon shifted production to their bew "Radar Range". The
Japanese soon caught up with their ubiquitous microwave ovens. They were
more motivated. Our houses were already equipped with oil, gas, and
electric ranges aplenty. Everyone, it turned out, was ready for
microwave too.

Klystrons were not washed up either. The most powerful generators ever
built were klystrons. The speed detector used to ticket your car
probably uses a laser. All radar isn`t pulsed radar. Radar altometers
use separate transmitter and receiver antennas. They transmit an FM
signal whose modulation frequency is changing at a certain rate. This is
continuously compared with the modulation frequency of the received echo
to tell how far away the reflection point is.

The television signal you watch off the air was probably generated by a
large klystron.

Best regards, Richard Harrison, KB5WZI