germanium power rectifier diodes

[[email protected]]

Hi,

I am curious about germanium power rectifier diodes. How do they compare
with silicon P-N types, how with silicon Schottky ones? Why did they
disappear long ago in the West (if they existed at all)? Are there only
disadvantages, or are there advantages too?

I suspect they show higher reverse currents, but may have a lower
voltage drop for not-to-high forward currents - at least in the 100V
plus region, where Schottky diodes do not reach. Any experiences out
there?

Examples of such things are the Russian 10A diodes D242 (100V), D243
(200V), D245 (300V), D246 (400V), and D247 (500V), as sold at
<http://globex.com.ru>. Does anybody know what type of package these do
come in (as this should tell somthing about the voltage drop)?

Thanks,

Martin.

 

[Sergey Kubushin]

[email protected] wrote:

[skipped]

Examples of such things are the Russian 10A diodes D242 (100V), D243
(200V), D245 (300V), D246 (400V), and D247 (500V), as sold at
<http://globex.com.ru>. Does anybody know what type of package these do
come in (as this should tell somthing about the voltage drop)?

All those a.m. diodes are SILICON rectifiers. They come in a screw-in case
with M6 bolt. There were russian germanium power rectifiers long ago - D302,
D303, D304, D305... They are long gone.

 

[[email protected]]

All those a.m. diodes are SILICON rectifiers. They come in a screw-in
case with M6 bolt. There were russian germanium power rectifiers long
ago - D302, D303, D304, D305... They are long gone.

Thanks for this, Sergey! A company here in Germany is selling them for
germanium ones! But they are selling D302's too (3A, 150V, which looks
much more believable for Ge). So my curiosity remains:

How do they compare with silicon P-N types, how with silicon Schottky
ones? Are there only disadvantages, or are there advantages too? I
suspect they show higher reverse currents, but may have a lower voltage
drop for not-too-high forward currents - at least in the 100V plus
region, where Schottky diodes do not reach.

Martin.

 

[Sergey Kubushin]

Thanks for this, Sergey! A company here in Germany is selling them for
germanium ones! But they are selling D302's too (3A, 150V, which looks
much more believable for Ge). So my curiosity remains:

How do they compare with silicon P-N types, how with silicon Schottky
ones? Are there only disadvantages, or are there advantages too? I
suspect they show higher reverse currents, but may have a lower voltage
drop for not-too-high forward currents - at least in the 100V plus
region, where Schottky diodes do not reach.

They DO have lower voltage drop, but they are not a competition for
Shottkies in any way. First of all, they are very slow. This is OK if you're
going to rectify 50/60 Hz, but as I recall they are already out of the game
at 400 Hz. Then, they have much lower maximum allowed junction temperature.

The only use for them that I can imagine is a serial protection diode (from
a reverse polarity) for some medium-current battery-powered equipment.

And I doubt D302 is 150V. Its a lowest voltage rectifier from D302-D305
family and I don't think D305 goes higher than 200 V (probably 150) so D302
is probably 50 V. But I didn't use 'em for more than 20 years so I can be
wrong...