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Steve Gibson · 28th Mar 2021, 1:35 am

Thanks for the feedback guys

I have tested the ECC83 and all is well

However. I have tested some EL84's with differing results (Anode and Grid @ 250v):

I have a couple of EL84's that measure 19.2 and 19.4mA @ -8.3volts control which is the closest I could get to some sort of documented spec at the end of the El84 data sheet for 2 tubes in AB push pull (i.e. 2 x 20mA)

At the standard -7.3volts control (Class A) where the data sheet says 48mA these tubes only read 28 - 29mA. which is way down on spec.

Also, on another set of valves (Russian EL84 equivalents), these read in the mid to high 20's at -8.3volts, BUT when come back from Test through Leak 2 and Leak 1, the led lights indicating a 'Leak' at Leak 2 until the valves cool down.

Do I have a bad set of Valves or is there something I'm missing when testing these valves?

Many Thanks

Steve

28th Mar 2021, 1:35 am	#1619
Steve Gibson Triode Join Date: Mar 2014 Location: Northampton, Northamptonshire, UK Posts: 49	Re: The "Sussex" Homebrew Valve Tester. Thanks for the feedback guys I have tested the ECC83 and all is well However. I have tested some EL84's with differing results (Anode and Grid @ 250v): I have a couple of EL84's that measure 19.2 and 19.4mA @ -8.3volts control which is the closest I could get to some sort of documented spec at the end of the El84 data sheet for 2 tubes in AB push pull (i.e. 2 x 20mA) At the standard -7.3volts control (Class A) where the data sheet says 48mA these tubes only read 28 - 29mA. which is way down on spec. Also, on another set of valves (Russian EL84 equivalents), these read in the mid to high 20's at -8.3volts, BUT when come back from Test through Leak 2 and Leak 1, the led lights indicating a 'Leak' at Leak 2 until the valves cool down. Do I have a bad set of Valves or is there something I'm missing when testing these valves? Many Thanks Steve