DIYbanter - View Single Post - Si-diodes in Second World War radar & Communication equipment

JosephKK[_2_]

On Wed, 23 Apr 2008 02:20:37 +0000 (UTC), (Don
Klipstein) wrote:

In article , JosephKK wrote:
On Tue, 22 Apr 2008 13:42:10 -0700, John Larkin
wrote:

On Tue, 22 Apr 2008 20:19:49 GMT, Rich Grise wrote:

On Sat, 12 Apr 2008 17:51:10 +0200, ronwer wrote:

I am doing a study into the early use of silicon diodes in radar and
communication equipment during the Second World War.

Did they even _have_ silicon diodes in WWII? I remember when they
announced the first transistor, some time in the early 1950's.

Thanks,
Rich

Yup. Most of the WWII radar diodes were silicon point-contact types,
Schottky diodes actually. The best 1943-vintage mixer parts were about
as good as any packaged schottky you can buy today... 0.2 Vf, 0.2 pF,
decent noise figures to 30 GHz.

The point-contact transistor was invented at Bell Labs in 1947. Most
of the relevant semiconductor theory - bandgaps, hole/electron
conduction, doping - was well understood by about 1940. The RadLab
guys didn't develop a PN-junction diode or the transistor because
their mandate was to develop radar to win the war.

John

Gee, John. Where do you get schottky diodes with V(f) below 0.2 V at
I(f) of 1 mA? All the ones i could find were over 0.33 V and mostly
0.4 to 0.5 V.

I am on a temporary setup now that does not have Acrobat, but I somewhat
remember Vishay-IR STPS1L30UPBF or 1N5818 dropping maybe .35 volt at 1
amp. These are 30 volt 1 amp Schottky rectifiers.

- Don Klipstein )

Two things, these are "modern" parts. Did the equivalent exist in the
1940's or 1950's? Do they make good microwave detector diodes? I
think not. Use time and use appropriate devices for comparison.