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Sci.Electronics.Basics -> Si-diodes in Second World War radar & Communication equipment
There are 103 messages in this thread.
You are currently looking at messages 100 to 103.
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Author: John FieldsDate: 11:58 27-04-08
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On Sat, 26 Apr 2008 17:06:12 -0700, JosephKK <quiettechblue@yahoo.com>
wrote:
>On Wed, 23 Apr 2008 08:51:25 -0500, John Fields
><jfields@austininstruments.com> wrote:
>
>>On Tue, 22 Apr 2008 19:00:35 -0700, JosephKK <quiettechblue@yahoo.com>
>>wrote:
>>
>>>On Tue, 22 Apr 2008 13:42:10 -0700, John Larkin
>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
>>>
>>>>On Tue, 22 Apr 2008 20:19:49 GMT, Rich Grise <rich@example.net>
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
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Author: leggDate: 13:31 27-04-08
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On Tue, 22 Apr 2008 21:04:37 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
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
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Author: Tom BruhnsDate: 14:51 28-04-08
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On Apr 26, 5:04 pm, JosephKK <quiettechb...@yahoo.com> wrote:
...
> >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
>
> 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.
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.
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