When I was building the 500 KHz transmitter I had a little accident with the 807 Transmitting valve ( I dropped a spanner on it and smashed the glass envelope)
Rather than waste the broken remains I decided to perform an autopsy on its internals - the following photos show what's inside.
The 807 Transmitter valve was manufactured in huge numbers during WW2. Its intended purpose was the power amplifier stages of HF Transmitters. Most WW2 tanks had one of these valves in its WS 19 set transceiver (even the Russians used them !) The valve was based on the RCA 6L6 beam tetrode which was a development of the British KT40 which proved too difficult to produce.
In 1966 (I was 13 years old) I bought an ex army tank radio from a company called "Johns Radio" advertising in Practical Wireless Magazine. These radio's covered 2 to 8 Mhz but had the transmitter disabled by removing the 807 Valve - That did not stop me for long however and soon the old 19 set was transmitting again.
