"Jon Kirwan" wrote in message
...
On Thu, 20 Aug 2009 20:30:19 -0700, John Larkin
wrote:

On Thu, 20 Aug 2009 22:07:46 -0500, "Martin H. Eastburn"
wrote:

First, Si diodes were not used in WW II. The PN SI diode wasn't invented
yet.

Nearly all the radar first mixer diodes were silicon point-contact
types, essentially silicon schottky diodes.

See the MIT Rad Lab book, volume 15, "Crystal Rectifiers" for a bunch
of WWII (and pre-war) stuff about diode development. This is from that
book:

ftp://jjlarkin.lmi.net/RadDiode2.JPG

ftp://jjlarkin.lmi.net/RadLabDiodes.JPG

Selenium wafers and sticks were the power types
and point or whisker diodes for RF. [ I have some of these in lead
cans ]

In the 60's it was still that way.

Funny, I recall using lots of silicon PN diodes (and SCRs, and
transistors, and tunnel diodes) in the early 1960's. Tek was using
GaAs diodes in their sampling scopes ca 1964.

Silicon diodes were developed by bell labs for internal telephone use
but semiconductor had to be invented first.

No. See the RadLab book.

Look at the date of the transistor. Silicon diode and Germanium diode.

I know Radar in B52's were using Selenium and Germanium for RF.

Selenium was never used in RF or radar, except maybe power supplies.
Far too slow.

John

It was certainly used in the power supplies. Not maybe. I actually
owned a radar unit that was commissioned for navy service in 1944.
Nice selenium series stacks used as diodes in at least some of the
power supplies. Also used vacuum tube VR150's for regulators.

Jon


VR150 is not a vacuum tube - it's gas filled (argon/neon), cold cathode.

Chris