D226 Diode (Silicon or Germanium) - UK Vintage Radio Repair and Restoration Discussion Forum

Miguel Lopez · 20th May 2014, 9:13 pm

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

paulsherwin · 20th May 2014, 10:25 pm

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.

Maarten · 23rd May 2014, 1:44 pm

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.

Miguel Lopez · 23rd May 2014, 5:04 pm

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

Miguel Lopez · 29th May 2014, 3:16 pm

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.

Paul Stenning · 29th May 2014, 6:53 pm

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!

Miguel Lopez · 29th May 2014, 7:35 pm

Why should I?

cmjones01 · 29th May 2014, 9:39 pm

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

20th May 2014, 9:13 pm	#1
Miguel Lopez Heptode Join Date: Dec 2011 Location: Mayabeque, Cuba Posts: 617	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 __________________ When electrons move, things happen. There's nothing you can do that can't be done.

20th May 2014, 10:25 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	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.

23rd May 2014, 1:44 pm	#3
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,203	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.

23rd May 2014, 5:04 pm	#4
Miguel Lopez Heptode Join Date: Dec 2011 Location: Mayabeque, Cuba Posts: 617	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 __________________ When electrons move, things happen. There's nothing you can do that can't be done.

29th May 2014, 6:53 pm	#6
Paul Stenning Administrator Join Date: Dec 2002 Location: Cardiff Posts: 9,073	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! __________________ Paul Stenning Forum Admin/Owner and BVWS Webmaster

29th May 2014, 7:35 pm	#7
Miguel Lopez Heptode Join Date: Dec 2011 Location: Mayabeque, Cuba Posts: 617	Re: D226 Diode (Silicon or Germanium) Why should I? __________________ When electrons move, things happen. There's nothing you can do that can't be done.

29th May 2014, 9:39 pm	#8
cmjones01 Nonode Join Date: Oct 2008 Location: Warsaw, Poland and Cambridge, UK Posts: 2,681	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 __________________ What's going on in the workshop? http://martin-jones.com/