Copper Oxide Rectifier - UK Vintage Radio Repair and Restoration Discussion Forum

Neil Purling · 2nd Nov 2019, 2:23 pm

Does anyone make these devices any more?
I know that there is a 'boutique' source of Selenium Rectifiers, or at least there was one in the U.S.
But what of this older rectifying device and alternative to a valve rectifier.

G6Tanuki · 2nd Nov 2019, 2:41 pm

Copper Oxide ones are still made - as replacement parts for specialist low-voltage-high-current operations like industrial electroplating.

But they're really not that efficient - and (like their Selenium brethren) do degrade significantly with age.

Given that in the last 60-odd years we've learned a lot more about semiconducting materials and how to use them - giving rise to the likes of the Schottky diode - it's perfectly understandable that copper-oxide/selenium rectifiers have gone the way of the dodo. I am not aware of anyone still producing 'consumer' copper-oxide or selenium rectifiers, as the market-demand would be tiny!

Ed_Dinning · 2nd Nov 2019, 9:09 pm

Hi Neil, what is the rectifier for and what are its ratings. From these details is should be possible to sub a modern device.
From memory there should not be an aging process with copper oxide, but I do believe the clamping force plays a big part in how good they are.

Metal Rectifier Engineering ~ Richards has all the details

Ed

Neil Purling · 3rd Nov 2019, 3:53 pm

The radio we are talking about is the typical post-war 3 valve TRF with a large amount of War Surplus components.
Does 50-70mA sound reasonable? The HT load is going to be mainly the output stage. These kit radios could get very weird valve types used. It'd be great to substitute an old stack for a replacement one which you could trust not to stink the place out.

Ed_Dinning · 3rd Nov 2019, 8:24 pm

Hi Neil, if it stinks it would be selenium, not copper oxide

Ed

Craig Sawyers · 3rd Nov 2019, 11:46 pm

Quote:

Originally Posted by G6Tanuki

Given that in the last 60-odd years we've learned a lot more about semiconducting materials and how to use them - giving rise to the likes of the Schottky diode - it's perfectly understandable that copper-oxide/selenium rectifiers have gone the way of the dodo. I am not aware of anyone still producing 'consumer' copper-oxide or selenium rectifiers, as the market-demand would be tiny!

Try https://www.gdrectifiers.co.uk/produ...um_rectifiers/

Craig

Neil Purling · 5th Nov 2019, 10:59 am

I have e-mailed an enquiry to the business Craig mentioned.

Craig Sawyers · 6th Nov 2019, 2:24 am

The guys at GD made two Se rectifiers for the restoration of the Lorenz SZ42 cipher machine I carried out about 12 years ago. They made them to my CAD drawings and even painted them the same colour as the German originals.

They use Aluminium plates instead of the iron plates that were used back in the day, so of course do not corrode, and have a long service life.

Good luck - I hope they can help you.

Craig

2nd Nov 2019, 2:23 pm	#1
Neil Purling Nonode Join Date: Jul 2005 Location: Hull, East Yorkshire, UK. Posts: 2,087	Copper Oxide Rectifier Does anyone make these devices any more? I know that there is a 'boutique' source of Selenium Rectifiers, or at least there was one in the U.S. But what of this older rectifying device and alternative to a valve rectifier.

2nd Nov 2019, 2:41 pm	#2
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Copper Oxide Rectifier Copper Oxide ones are still made - as replacement parts for specialist low-voltage-high-current operations like industrial electroplating. But they're really not that efficient - and (like their Selenium brethren) do degrade significantly with age. Given that in the last 60-odd years we've learned a lot more about semiconducting materials and how to use them - giving rise to the likes of the Schottky diode - it's perfectly understandable that copper-oxide/selenium rectifiers have gone the way of the dodo. I am not aware of anyone still producing 'consumer' copper-oxide or selenium rectifiers, as the market-demand would be tiny!

2nd Nov 2019, 9:09 pm	#3
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Copper Oxide Rectifier Hi Neil, what is the rectifier for and what are its ratings. From these details is should be possible to sub a modern device. From memory there should not be an aging process with copper oxide, but I do believe the clamping force plays a big part in how good they are. Metal Rectifier Engineering ~ Richards has all the details Ed

3rd Nov 2019, 3:53 pm	#4
Neil Purling Nonode Join Date: Jul 2005 Location: Hull, East Yorkshire, UK. Posts: 2,087	Re: Copper Oxide Rectifier The radio we are talking about is the typical post-war 3 valve TRF with a large amount of War Surplus components. Does 50-70mA sound reasonable? The HT load is going to be mainly the output stage. These kit radios could get very weird valve types used. It'd be great to substitute an old stack for a replacement one which you could trust not to stink the place out.

3rd Nov 2019, 8:24 pm	#5
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Copper Oxide Rectifier Hi Neil, if it stinks it would be selenium, not copper oxide Ed

5th Nov 2019, 10:59 am	#7
Neil Purling Nonode Join Date: Jul 2005 Location: Hull, East Yorkshire, UK. Posts: 2,087	Re: Copper Oxide Rectifier I have e-mailed an enquiry to the business Craig mentioned.

6th Nov 2019, 2:24 am	#8
Craig Sawyers Dekatron Join Date: Nov 2010 Location: Oxford, UK. Posts: 4,984	Re: Copper Oxide Rectifier The guys at GD made two Se rectifiers for the restoration of the Lorenz SZ42 cipher machine I carried out about 12 years ago. They made them to my CAD drawings and even painted them the same colour as the German originals. They use Aluminium plates instead of the iron plates that were used back in the day, so of course do not corrode, and have a long service life. Good luck - I hope they can help you. Craig