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John Fields
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 Posted: Wed Apr 23, 2008 6:51 pm Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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On Tue, 22 Apr 2008 19:00:35 -0700, JosephKK <quiettechblue@yahoo.com>
wrote:
[quote]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.
[/quote]
---
I just pulled a random 1N5817 out of stock, put 1.000 milliamps
through it and measured 0.1383 volts across it.
JF |
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Eeyore
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| Posted: Wed Apr 23, 2008 7:28 pm Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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John Fields wrote:
[quote]JosephKK wrote:
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.
[/quote]
Sounds about right.
I have a book here about the develpoment of active devices for radar and it>s
quite unambiguous about silicon being used for microwave diodes. The early
work was actually done by GEC and BTH of the UK in conjuction with military
R&D.
As ever the Americans refined the manufacturing process. The early ones were
virtually 'hand made'.
Graham |
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John Fields
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| Posted: Wed Apr 23, 2008 7:50 pm Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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On Wed, 23 Apr 2008 08:51:25 -0500, John Fields
<jfields@austininstruments.com> wrote:
[quote]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.
[/quote]
---
Just to make sure it wasn>t an anomaly, I measured 10 more and here>s
what I got:
If Vf
mA V
-------+-------+
1.000 0.1495
1.000 0.1350
1.000 0.1525
1.000 0.1344
1.000 0.1495
1.000 0.1355
1.000 0.1510
1.000 0.1532
1.000 0.1496
1.000 0.1370
The equipment was set up like this:
+-------[WAVETEK 27XT]---[10k]---+----------+
|+ |A |+
[HP 6216A] [DUT] [FLUKE 8060A]
|- | |-
+--------------------------------+----------+
The 8060A draws 25ľA on the 2 volt range, so the current out of the
6216A was set to 1.025mA for every reading in order to force 1.000mA
through the 1N5817s.
Turns out the power supply was impossible to adjust spot on, so I put
the 10k resistor in there to give me fewer ľA per degree of rotation
of the knob. Worked great.
JF |
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John Larkin
Guest
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| Posted: Wed Apr 23, 2008 7:52 pm Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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On Wed, 23 Apr 2008 09:50:13 -0500, John Fields
<jfields@austininstruments.com> wrote:
[quote]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.
---
Just to make sure it wasn>t an anomaly, I measured 10 more and here>s
what I got:
If Vf
mA V
-------+-------+
1.000 0.1495
1.000 0.1350
1.000 0.1525
1.000 0.1344
1.000 0.1495
1.000 0.1355
1.000 0.1510
1.000 0.1532
1.000 0.1496
1.000 0.1370
The equipment was set up like this:
+-------[WAVETEK 27XT]---[10k]---+----------+
|+ |A |+
[HP 6216A] [DUT] [FLUKE 8060A]
|- | |-
+--------------------------------+----------+
The 8060A draws 25ľA on the 2 volt range, so the current out of the
6216A was set to 1.025mA for every reading in order to force 1.000mA
through the 1N5817s.
Turns out the power supply was impossible to adjust spot on, so I put
the 10k resistor in there to give me fewer ľA per degree of rotation
of the knob. Worked great.
JF
[/quote]
Most DVM>s seem to output 1 mA on the diode-test range. I don>t know
how much of a convention that is. They do seem to disagree on how much
voltage they>ll indicate: some display the Vf of an LED, some say open
or overload or whatever.
John |
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Phil Allison
Guest
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| Posted: Wed Apr 23, 2008 7:58 pm Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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"John Fields"
[quote]I just pulled a random 1N5817 out of stock, put 1.000 milliamps
through it and measured 0.1383 volts across it.
[/quote]
** But you well knew that Motorola describe them as having " Extremely low
Vf " - now didn>t you ??
http://www.onsemi.com/pub_link/Collateral/1N5817-D.PDF
BTW:
how hot did you make it get first ?
..... Phil |
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John Larkin
Guest
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| Posted: Thu Apr 24, 2008 12:58 am Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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On Tue, 22 Apr 2008 21:40:49 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
[quote]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.
This is a silicon point-contact diode, essentially the same as the
WWII parts, expect that they get to use modern, very pure silicon:
http://www.micrometrics.com/pdfs/PC_SXBandMixer.pdf
Skyworks makes some very low capacitance (below 0.5 pF) schottkies
that are similar.
This is 300 mV *max* at 100 mA, so should be down there. I think the
schottky curve is sorta similar to the silicon PN curve, which is 60
mV per decade of current.
http://www.centralsemi.com/PDFs/products/CMHSH5-2L.PDF
I posted some WWII diode curves elsewhere, well under 200 mV at 1 mA.
Gee.
John
[/quote]
Central CMMSH1-20 is a really tiny, about 1206 size, 1 amp 20 volt
schottky, great for small buck switchers; measures 201 mV at 1 mA. But
it>s 280 pF!
John |
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John Popelish
Guest
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| Posted: Thu Apr 24, 2008 1:27 am Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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John Larkin wrote:
[quote]Central CMMSH1-20 is a really tiny, about 1206 size, 1 amp 20 volt
schottky, great for small buck switchers; measures 201 mV at 1 mA. But
it>s 280 pF!
[/quote]
I think if you do a Google search for "zero bias diode" you
will find things a lot more similar to 1N23 in electrical
characteristics.
--
Regards,
John Popelish |
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John Larkin
Guest
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| Posted: Thu Apr 24, 2008 1:51 am Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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On Wed, 23 Apr 2008 16:27:21 -0400, John Popelish <jpopelish@rica.net>
wrote:
[quote]John Larkin wrote:
Central CMMSH1-20 is a really tiny, about 1206 size, 1 amp 20 volt
schottky, great for small buck switchers; measures 201 mV at 1 mA. But
it>s 280 pF!
I think if you do a Google search for "zero bias diode" you
will find things a lot more similar to 1N23 in electrical
characteristics.
[/quote]
"Back diode" is interesting, too. They are, to my knowledge, the only
germanium diodes made using an ic-type mask process, and about the
only Ge diodes still made at all, except for photodiodes of course.
They are still the best microwave detectors.
John |
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John Fields
Guest
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| Posted: Thu Apr 24, 2008 3:03 am Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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On Wed, 23 Apr 2008 07:52:46 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
[quote]On Wed, 23 Apr 2008 09:50:13 -0500, John Fields
jfields@austininstruments.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.
---
Just to make sure it wasn>t an anomaly, I measured 10 more and here>s
what I got:
If Vf
mA V
-------+-------+
1.000 0.1495
1.000 0.1350
1.000 0.1525
1.000 0.1344
1.000 0.1495
1.000 0.1355
1.000 0.1510
1.000 0.1532
1.000 0.1496
1.000 0.1370
The equipment was set up like this:
+-------[WAVETEK 27XT]---[10k]---+----------+
|+ |A |+
[HP 6216A] [DUT] [FLUKE 8060A]
|- | |-
+--------------------------------+----------+
The 8060A draws 25ľA on the 2 volt range, so the current out of the
6216A was set to 1.025mA for every reading in order to force 1.000mA
through the 1N5817s.
Turns out the power supply was impossible to adjust spot on, so I put
the 10k resistor in there to give me fewer ľA per degree of rotation
of the knob. Worked great.
JF
Most DVM>s seem to output 1 mA on the diode-test range.
[/quote]
---
Into a short.
---
[quote]don>t know how much of a convention that is.
[/quote]
---
I have 5, and on the DIODE TEST function they put out:
EMCO DMR3250 1.3229 mA
SPECO DMR2500 1.2045 mA
WAVETEK DM5XL 1.0387 mA
WAVETEK 27XT 1.0098 mA
FLUKE 8060A 0.943 mA
So it seems to be pretty conventional.
---
[quote]They do seem to disagree on how much
voltage they>ll indicate: some display the Vf of an LED, some say open
or overload or whatever.
[/quote]
---
Depends on the Vf of the LED, I suspect. All of mine display the
voltage drop of the DUT, whether it>s a resistor or a diode or
whatever, and display overload when the voltage gets to be > 1.999V.
Here are the results of an experiment I just finished running:
+-------------------------------------+
| |
+--[SOURCE]--------[R]--------[LOAD]--+
VOLTS OHMS MILLIAMPS
DMR3520 0.123 0 1.3229
2.000 12300 0.1773
DMR2500 0.100 0 1.2045
2.000 1913 0.616
DM5XL 0.106 0 1.0387
2.000 6072 0.3273
27XT 0.101 0 1.0098
2.000 5423 0.3662
8060A 0.095 0 0.943
2.000 2056 0.934
The series resistance was a Clarostat 240C decade resistor box, and
for the first four entries the load was the Fluke 8060A. In the last
one it was the Wavetek 27XT.
The test was run by measuring the current from the source (the meter
switched to the DIODE TEST function), recording it, then recording the
voltage indicated on the source>s display, then switching in
resistance until the source>s display indicated overload.
Interesting to note that the Fluke has an almost constant current
source feeding the DUT, while none of the others do.
JF |
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John Fields
Guest
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| Posted: Thu Apr 24, 2008 3:08 am Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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On Thu, 24 Apr 2008 00:58:28 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:
[quote]
"John Fields"
I just pulled a random 1N5817 out of stock, put 1.000 milliamps
through it and measured 0.1383 volts across it.
** But you well knew that Motorola describe them as having " Extremely low
Vf " - now didn>t you ??
http://www.onsemi.com/pub_link/Collateral/1N5817-D.PDF
[/quote]
---
Actually, I didn>t, but thanks for the clue.
---
[quote]BTW:
how hot did you make it get first ?
[/quote]
---
Well, I showed it my penis...
JF |
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John Popelish
Guest
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| Posted: Thu Apr 24, 2008 3:39 am Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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John Larkin wrote:
[quote]On Wed, 23 Apr 2008 16:27:21 -0400, John Popelish <jpopelish@rica.net
wrote:
John Larkin wrote:
Central CMMSH1-20 is a really tiny, about 1206 size, 1 amp 20 volt
schottky, great for small buck switchers; measures 201 mV at 1 mA. But
it>s 280 pF!
I think if you do a Google search for "zero bias diode" you
will find things a lot more similar to 1N23 in electrical
characteristics.
"Back diode" is interesting, too. They are, to my knowledge, the only
germanium diodes made using an ic-type mask process, and about the
only Ge diodes still made at all, except for photodiodes of course.
They are still the best microwave detectors.
[/quote]
Yes, interesting, but not very much like the characteristics
of 1N23.
--
Regards,
John Popelish |
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JosephKK
Guest
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| Posted: Sun Apr 27, 2008 4:39 am Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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On Wed, 23 Apr 2008 02:09:10 +0000 (UTC), don@manx.misty.com (Don
Klipstein) wrote:
[quote]In article <pd3t04l5i3gck6c4r87f0a51e2qr5hia0e@4ax.com>, JosephKK wrote:
On Sun, 20 Apr 2008 20:45:08 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
On 21 Apr 2008 03:03:32 GMT, JosephKK <quiettechblue@yahoo.com> wrote:
On 20 Apr 2008 13:59:36 -0700, Don Bowey <dbowey@comcast.net>wrote:
Do you have a solid reference for that? "Credible" references I found
said they were silicon.
The most conclusive evidence i know of, is someone here who actually
put one to test and the result was germanium. A heck of a lot of
"official" or "authoritative" records are pure fertilizer.
What test?
V(f) @ 1 mA. Result < 180 mV. Thus Ge, not Si.
I have seen silicon schottky diodes that drop about .3 volt at 1 amp.
- Don Klipstein (don@misty.com)
[/quote]
Not arguing that. Would that diode make a good microwave detector? |
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JosephKK
Guest
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| Posted: Sun Apr 27, 2008 4:42 am Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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On Tue, 22 Apr 2008 21:04:37 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
[quote]On Tue, 22 Apr 2008 18:17:10 -0700, JosephKK <quiettechblue@yahoo.com
wrote:
On Sun, 20 Apr 2008 20:45:08 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
On Mon, 21 Apr 2008 03:03:32 GMT, JosephKK <quiettechblue@yahoo.com
wrote:
On Sun, 20 Apr 2008 13:59:36 -0700, Don Bowey <dbowey@comcast.net
wrote:
On 4/20/08 11:26 AM, in article am2n04hciv1c0trs9vmfala4pf78ic80nb@4ax.com,
"JosephKK" <quiettechblue@yahoo.com> wrote:
On Sat, 12 Apr 2008 11:29:18 -0500, John Fields
jfields@austininstruments.com> wrote:
On Sat, 12 Apr 2008 11:24:19 -0500, John Fields
jfields@austininstruments.com> wrote:
On Sat, 12 Apr 2008 17:51:10 +0200, "ronwer"
neo.dymium.removethisfirst@dontwantspam.yahoo.com> wrote:
Hi!
I am doing a study into the early use of silicon diodes in radar and
communication equipment during the Second World War.
What I would be interested in is as follows:
-type numbers of the diodes
---
1N23 is a good place to start.
---
Oops... brain fart.
The 1N23 didn>t appear until the '50>s, I believe.
JF
Not only that it was germanium not silicon.
Do you have a solid reference for that? "Credible" references I found said
they were silicon.
The most conclusive evidence i know of, is someone here who actually
put one to test and the result was germanium. A heck of a lot of
"official" or "authoritative" records are pure fertilizer.
What test?
John
V(f) @ 1 mA. Result < 180 mV. Thus Ge, not Si.
Here are some curves from the RadLab book:
ftp://66.117.156.8/RadLabDiodes.JPG
ftp://66.117.156.8/RadDiode2.JPG
Your data point is dead on the point-contact Silicon diode curve.
John
[/quote]
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. |
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JosephKK
Guest
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| Posted: Sun Apr 27, 2008 4:52 am Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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On Wed, 23 Apr 2008 02:20:37 +0000 (UTC), don@manx.misty.com (Don
Klipstein) wrote:
[quote]In article <hr5t04l9866fsp3r3s3sqgjcasco3fv1gr@4ax.com>, JosephKK 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 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 (don@misty.com)
[/quote]
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. |
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JosephKK
Guest
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| Posted: Sun Apr 27, 2008 5:06 am Post subject: Re: Si-diodes in Second World War radar & Communication equi |
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On Wed, 23 Apr 2008 08:51:25 -0500, John Fields
<jfields@austininstruments.com> wrote:
[quote]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
[/quote]
And what is the junction capacitance and does it make a good microwave
mixer? |
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