On Sat, 26 Apr 2008 17:06:12 -0700, JosephKK
wrote:

On Wed, 23 Apr 2008 08:51:25 -0500, John Fields
wrote:

On Tue, 22 Apr 2008 19:00:35 -0700, 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 just pulled a random 1N5817 out of stock, put 1.000 milliamps
through it and measured 0.1383 volts across it.

JF

And what is the junction capacitance and does it make a good microwave
mixer?

---
Who cares?

Your statement that: "All the ones i could find were over 0.33 V and
mostly 0.4 to 0.5 V." had nothing to do with junction capacitance and
suitability for use as microwave mixers, all you were trying to do was
discredit Larkin by using bogus data. Which Schottky diodes were you
referring to, BTW?

JF