Si-diodes in Second World War radar & Communication equipment

Yes, interesting, but not very much like the characteristics of 1N23.

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Regards,

John Popelish

HSMS-2850 is about 0.2V @ 1mA, but it also has a PIV rating of just 2 volts. Capacitance is considerably less than that CMMSH1-20, though. I don't have any point-contact diodes to compare it with, but can tell you that it's useful for detecting RF down to a bit below 100uV, possibly less if you're careful with thermal potentials and the like, or chop the signal.

Cheers, Tom

The 1N21 and 1N23 were actually silicon point-contact diodes. The other common 1940's rectifier was copper oxide, used for small-signal rectification, notably for the AC ranges of VOM's.

John

Not arguing that. Would that diode make a good microwave detector?

Say what you will. I was playing with 1950's (or older) parts in the

1960's. All the datasheets back then said Ge. Compare proper contemporaneous parts.

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.

I am getting a little tired so may blatting about modern parts as if they were available in the 1940'sand 1950's. The question is "What were the original parts made of?"

Newer implementations is, at best, a side issue.

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

Were germanium PN junction diodes of the period (or any later period) good microwave detectors? I thought they were pretty slow.

--
Regards,

John Popelish

Well, I'm sure your memory is more accurate than my books and datasheets.

John

I found an oral history from someone who was involved in the research at the time (Art Uhlir Jr.). It is a bit scattered, but very close to this discussion:

Bottom of page 10 gets to the 1N23.

--
Regards,

John Popelish

I still have a few 1N21 and 1N23 diodes used as mixers in ancient X-band radar receivers. 2K25 klystron for a local oscillator.

Anyway, they're both silicon, not germanium. See:

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Corroborates my thought that they were probably point-contact.

...Jim Thompson

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Maybe they changed from Si to Ge ?

My IEE book on the subject says the early radar diodes were silicon though.

Graham

"Eeysore" JosephKK

** Wake up - you pathetic dope.

You are wasting your remaining life arguing with a bona-fide " flat earther " here.

Stop now - or else you will fall right off the edge ... .. ... ... ... .. .

T - hump . . .. ..

... Phil

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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

According to the Henney's Radio Engineering Handbook 4th ed (1950),

1N25 and 1N26 silcon point contact 'crystals' for use in UHF and SHF converters (1 to 25 GHz) are discussed in commercial publications by Cornelius in 1945; 1N34 and 1N38 germanium 'crystals' for use at VHF (~200mHz) appear in publications the following year.

Waritime radar operated in the 195MHz-10,000MHz range.

1N21B 'crystal' mixers were used by GE in commercial 2GHz relay service before 1948 and similar parts were used by Bell in multiplex telephone and television relay systems at 4GHz around the same time.

RL

On Apr 26, 5:04 pm, JosephKK wrote: ...

WTF??!! YOU are the one, a day before my posting quoted above, who pondered in a post directly in the thread above mine about where to get Schottky diodes with Vf below 0.2V. I would suppose you weren't asking there about parts from the 40's or 50's. Don't complain about drift into new areas after willing taking part in the drift yourself. Please have the grace to not complain about answers to the very questions you've asked. Alternatively, just ignore the drift. To some of us, the side issues become more interesting than the original topic.

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

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.

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

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.

Different times scan down the page...

Silicon came later since it was hard to use and Ge was the center of it all.

Mart> Hi!