AEI CG90 diode data? - UK Vintage Radio Repair and Restoration Discussion Forum

MrBungle · 15th Sep 2016, 11:35 am

I've just obtained a box full of junk and there are some interesting diodes in it. Appears to be from an old Tektronix 545 chassis (unfortunately only parts, but that's what I'm after really) and I've extracted a very low forward voltage glass encapsulated black diodes, marked AEI CG90. Forward voltage drop is a respectably low 0.26v.

Does anyone know any details about these. They appear to be entirely mysterious. I can't find any data on them anywhere.

Possibly point contact, most likely germanium but could do with some info on reverse breakdown / capacitance and forward current etc.

julie_m · 15th Sep 2016, 2:37 pm

You should be able to measure the PIV of an unknown diode, as long as you have a PSU that will turn up high enough. Keep increasing the series resistance as you increase the voltage, so as to keep the power dissipation down; you don't want to blow them up while testing.

ms660 · 15th Sep 2016, 2:42 pm

AEI...CG90H...Germanium, gold bonded.

PIV = 25 Volts.

Maximum forward current = Not given.

Maximum reverse current = 7uA at 10 Volts.

Maximum rectified current = 80mA.

Application = Very high speed switching.

Ref: Radio Valve Data, Iliffe, 8th Edition.

Lawrence.

MrBungle · 15th Sep 2016, 2:56 pm

Excellent - many thanks!

MrBungle · 15th Sep 2016, 3:19 pm

As mentioned by julie_m I measured the PIV of one and it conducted around 32v and promptly broke in two with a little puff of smoke. Oops. Also some of these appear to be bidirectional diodes and some are nonodes I.e open circuit.

I can see why this scope was scrapped - I've pulled perhaps 100 components out of the assemblies and I have about 11 that are still in tolerance and operational. Got some nice switches, pots and Tektronix ceramic strips so not too bad.

Boater Sam · 15th Sep 2016, 4:34 pm

Some of them are now Dedodes too.

When I think of the hours that our lab scopes did as heaters in winter, I'm not surprised.

15th Sep 2016, 11:35 am	#1
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	AEI CG90 diode data? I've just obtained a box full of junk and there are some interesting diodes in it. Appears to be from an old Tektronix 545 chassis (unfortunately only parts, but that's what I'm after really) and I've extracted a very low forward voltage glass encapsulated black diodes, marked AEI CG90. Forward voltage drop is a respectably low 0.26v. Does anyone know any details about these. They appear to be entirely mysterious. I can't find any data on them anywhere. Possibly point contact, most likely germanium but could do with some info on reverse breakdown / capacitance and forward current etc.

15th Sep 2016, 2:37 pm	#2
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: AEI CG90 diode data? You should be able to measure the PIV of an unknown diode, as long as you have a PSU that will turn up high enough. Keep increasing the series resistance as you increase the voltage, so as to keep the power dissipation down; you don't want to blow them up while testing. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

15th Sep 2016, 2:42 pm	#3
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: AEI CG90 diode data? AEI...CG90H...Germanium, gold bonded. PIV = 25 Volts. Maximum forward current = Not given. Maximum reverse current = 7uA at 10 Volts. Maximum rectified current = 80mA. Application = Very high speed switching. Ref: Radio Valve Data, Iliffe, 8th Edition. Lawrence.

15th Sep 2016, 2:56 pm	#4
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: AEI CG90 diode data? Excellent - many thanks!

15th Sep 2016, 3:19 pm	#5
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: AEI CG90 diode data? As mentioned by julie_m I measured the PIV of one and it conducted around 32v and promptly broke in two with a little puff of smoke. Oops. Also some of these appear to be bidirectional diodes and some are nonodes I.e open circuit. I can see why this scope was scrapped - I've pulled perhaps 100 components out of the assemblies and I have about 11 that are still in tolerance and operational. Got some nice switches, pots and Tektronix ceramic strips so not too bad.

15th Sep 2016, 4:34 pm	#6
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: AEI CG90 diode data? Some of them are now Dedodes too. When I think of the hours that our lab scopes did as heaters in winter, I'm not surprised.