EH EL34 heater-cathode leakage

[Rhodesplyr]

I'm working on a Marshal JCM800 2210 head, and the EL34s in it are Electro-Harmonix production branded as "Mojotone." (It only has two EL34s in it since the owner likes to run it as a lower-wattage amp, but he does set the output impedance to compensate.)

Both EL34s show exactly the same amount of heater-cathode leakage in my EICO tester, ~5 Megohms. Is that typical for these? I have just about every other brand of EL34 in my possession, and they show virtually no measurable leakage.

Otherwise, the tubes test and work just fine.

Thanks,
David

[Euthymia]

Originally Posted by Rhodesplyr

I'm working on a Marshal JCM800 2210 head, and the EL34s in it are Electro-Harmonix production branded as "Mojotone." (It only has two EL34s in it since the owner likes to run it as a lower-wattage amp, but he does set the output impedance to compensate.)

Both EL34s show exactly the same amount of heater-cathode leakage in my EICO tester, ~5 Megohms. Is that typical for these? I have just about every other brand of EL34 in my possession, and they show virtually no measurable leakage.

Otherwise, the tubes test and work just fine.

Thanks,
David

I am recently seeing the same thing using my EICO 667. My tube supplier says he is looking into it, but for the moment, I'm treating the tubes as "good."

They work fine in amps, which is really the proof. If my clients have problems with them, I'll swap their tubes out.