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SE EL34

:

9/6/2000 10:16 PM

I ran my homebrew P1 with an EL34 (it's a cathode biased SE amp).
I get around 12V across 250 ohm cathode resistor.
Plate voltage is 230V.
If my math is correct that's 48mA bias and around 11W plate dissipation.
Is it good?

With a Sovtek 5881WXT measures are almost the same (44mA bias, 10W).

May I think everything's all right?
Please tell me if my amp is running safe.

Thanks in advance

Giacomo

9/7/2000 11:30 PM

Re: Please recipe!

Hi gt:

I ran a bench project with a SE Sovtek EL34 at higher voltages and 70ma, seemed to do fine for a decent time.

Then pushed it to 90ma for a short period without incident also, less than a half hour, it was HOT! I was using a small fan on the tube both times though.

Looks to me like you are right in the ballpark for a fairly conservative amp considering it is Class A. Just keep an eye on the temperature of the transformers, tube, and anything close enough to be damaged by the greater-than-average heat needed to run in Class A.

The US version of the EL34 was the 6CA7, it was rated at 25W, the only example conditions in the GE book for their 6CA7 have it at 250 V and 100ma. The 5881WXT is OK where you have it also, but it would probably die sooner than the EL34 if you tried to increase it to 70 or 90ma.

Hope this helps,
Mike

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