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Old 20th May 2014, 9:13 pm   #1
Miguel Lopez
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Default D226 Diode (Silicon or Germanium)

Hello

Since I started to enjoy electronics, I have always use the D226 Soviet diode.

It has been available in Cuba for years as almost all the vintage Soviet equipment used it. I have always thought that it was a Silicon diode, but now I read on radiomuseum.org that it is a Germanium diode
http://www.radiomuseum.org/tubes/tube_d226.html

So I made some test, cause I have always seen a voltage drop of 0.6 to 0.8 volts on this kind of diodes.

I measure the voltage drop as I passed a current throught it. With 5mA it dropped 0,55V and with 40mA, it dropped 0,8V. It behaves as a Silicon diode but with some differences.

I did the same test wit a KD202 diode (which I know is a Silicon diode, due to the prefix K [кремний]) and it dropped between 0,58 and 0,65V with the same variation of current.

AFAIK, Germanium P-N junctions drop 0,2 to 0,3V when forward biased.

So, I think there are several possibilities here:

1.) It is a Silicon diode.
2.) It is a special kind of Germanium diode
3.) It is three Germanium diodes in series.

Any help about this?

Thanks in advance
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Old 20th May 2014, 10:25 pm   #2
paulsherwin
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Default Re: D226 Diode (Silicon or Germanium)

It is behaving like a silicon diode, and it looks like an early silicon rectifier physically, but the current rating (300mA) is low for a silicon rectifier.

I think the most probable explanation is that the radiomuseum information is incorrect, but that's just a guess.
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Old 23rd May 2014, 1:44 pm   #3
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Default Re: D226 Diode (Silicon or Germanium)

I would go with that guess too. Only the original datasheets could confirm what is the case.

In a 3rd party reference table found at http://www.datasheetarchive.com/dlma...870000-135.pdf it is listed as an Si* diode. Unfortunately, it isn't mentioned what the * refers to.
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Old 23rd May 2014, 5:04 pm   #4
Miguel Lopez
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Default Re: D226 Diode (Silicon or Germanium)

I have a Catalog of Russian Component on .DJVU format which state that one of the Western equivalents of the D226 should be the: BAW14, MC030, MC51 and PS633; among others. All of this diodes are Silicons (I have found that the characteristics are not really equivalent according to the links bellow)

http://americanmicrosemi.com/informa...c/?ss_pn=BAW14
http://americanmicrosemi.com/informa...c/?ss_pn=MC030
http://americanmicrosemi.com/informa...ec/?ss_pn=MC51
http://americanmicrosemi.com/informa...c/?ss_pn=PS633

The Russian Catalog can be downloaded here:
http://radiosit.ru/news/diody_tirist...011-10-26-1788
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Old 29th May 2014, 3:16 pm   #5
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Default Re: D226 Diode (Silicon or Germanium)

It seems that definitively it is a Silicon diode. A friend of mine send me this yesterday (I couldn't see it till today) on HTML format. He said it was from a Russian page that no longer exist. I convert it to PDF to show it here.
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File Type: pdf Russian Diodes.pdf (36.2 KB, 133 views)
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Old 29th May 2014, 6:53 pm   #6
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Default Re: D226 Diode (Silicon or Germanium)

I've grabbed a copy for the data section on my free Vintage Radio Info website http://www.vintage-radio.info/data - I hope you don't mind!
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Old 29th May 2014, 7:35 pm   #7
Miguel Lopez
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Default Re: D226 Diode (Silicon or Germanium)

Why should I?
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Old 29th May 2014, 9:39 pm   #8
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Default Re: D226 Diode (Silicon or Germanium)

I'd guess that it's a silicon diode, but not a very good one, hence the extra forward voltage drop. It may have a high internal resistance due to some property of the junction or the way the wires are attached.

Chris
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