How to I.D some double triodes - UK Vintage Radio Repair and Restoration Discussion Forum

vinrads · 27th May 2022, 11:00 am

I have a load of ECC?? all with print missing is there an easy way of I.D ing these. Mick.

snowman_al · 27th May 2022, 11:32 am

Unfortunately not easily.
For example a Mullard ECC82 and ECC83 look the some, and you cannot see the grid structure. The heater currents are all the same so no help either. You may be lucky and find an etch code near the base that will help.
Then other manufactures used different anode structures, but the same problem, they often shared the same look between types.

Only sure way needs a valve tester or method of measuring anode current at a specific -ve voltage on the grid.

ms660 · 27th May 2022, 11:39 am

Some don't have tapped heaters if that's any help in narrowing things down.

Lawrence.

snowman_al · 27th May 2022, 11:53 am

Good point, I assumed from the question we were just looking for ECC81, 82 and 83s. A quick resistance check from either pin 4 or 5 to pin 9 would sort them out.

A few pictures would soon confirm.

vinrads · 27th May 2022, 6:14 pm

Just to confirm they are all ECC81/2/3 Mick.

ms660 · 28th May 2022, 11:13 am

The anodes of the ECC81 should be noticeably shorter than those of the ECC82 & ECC83.

Lawrence.

paulsherwin · 28th May 2022, 3:42 pm

You could lash up a test rig to separate the 82s and 83s. The slope is completely different.

vinrads · 28th May 2022, 5:01 pm

Thanks Paul I was thinking along the same lines, Mick.

Maarten · 29th May 2022, 12:26 am

All of the print missing, but is it? You're probably aware but in case you're not.. In the Philips universe, valves got stamped with a small two line factory code either near the bottom on the side or on the bottom itself (old valves), sometimes mistakenly referred to as etch codes. This is often done in somewhat durable ink and a bite more sturdy than the normal chalc print of brand and type number since it had to survive said chalc printing process and would also be used to determine warranty and quality issues.

27th May 2022, 11:00 am	#1
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,763	How to I.D some double triodes I have a load of ECC?? all with print missing is there an easy way of I.D ing these. Mick.

27th May 2022, 11:32 am	#2
snowman_al Octode Join Date: Dec 2018 Location: Llandeilo, West Wales, UK. Posts: 1,092	Re: How to I.D some double triodes Unfortunately not easily. For example a Mullard ECC82 and ECC83 look the some, and you cannot see the grid structure. The heater currents are all the same so no help either. You may be lucky and find an etch code near the base that will help. Then other manufactures used different anode structures, but the same problem, they often shared the same look between types. Only sure way needs a valve tester or method of measuring anode current at a specific -ve voltage on the grid. __________________ Never Leave Well Enough Alone...

27th May 2022, 11:39 am	#3
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: How to I.D some double triodes Some don't have tapped heaters if that's any help in narrowing things down. Lawrence.

27th May 2022, 11:53 am	#4
snowman_al Octode Join Date: Dec 2018 Location: Llandeilo, West Wales, UK. Posts: 1,092	Re: How to I.D some double triodes Good point, I assumed from the question we were just looking for ECC81, 82 and 83s. A quick resistance check from either pin 4 or 5 to pin 9 would sort them out. A few pictures would soon confirm. __________________ Never Leave Well Enough Alone...

27th May 2022, 6:14 pm	#5
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,763	Re: How to I.D some double triodes Just to confirm they are all ECC81/2/3 Mick.

28th May 2022, 11:13 am	#6
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: How to I.D some double triodes The anodes of the ECC81 should be noticeably shorter than those of the ECC82 & ECC83. Lawrence.

28th May 2022, 3:42 pm	#7
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,960	Re: How to I.D some double triodes You could lash up a test rig to separate the 82s and 83s. The slope is completely different.

28th May 2022, 5:01 pm	#8
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,763	Re: How to I.D some double triodes Thanks Paul I was thinking along the same lines, Mick.

29th May 2022, 12:26 am	#9
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,203	Re: How to I.D some double triodes All of the print missing, but is it? You're probably aware but in case you're not.. In the Philips universe, valves got stamped with a small two line factory code either near the bottom on the side or on the bottom itself (old valves), sometimes mistakenly referred to as etch codes. This is often done in somewhat durable ink and a bite more sturdy than the normal chalc print of brand and type number since it had to survive said chalc printing process and would also be used to determine warranty and quality issues.