Re: Doesn't it depend on how the tubes are going to be used?

Posted by Jim McShane (D) on December 9, 2006 at 15:51:11

In Reply to: Doesn't it depend on how the tubes are going to be used? posted by Ray Moth on December 9, 2006 at 13:42:40:

Ray,

"I is most important in PP to balance the currents in the OPT primary"

Important? Yes. Most important? No - IMHO primary current balance is moot if the tubes keep blowing up!

It is true in a pure pentode mode amp the plate currents are the only current flowing through the OPT - but that is not true of the tube. It still has both plate and screen current flowing through the cathode (unless it's a triode of course!). So if the bias is set by measurement of current in the cathode then you must consider screen current.

I know what you are driving at, and your point is well taken. And what you say is true in a few cases where the bias is measured at another spot besides the cathode and no screen current is present in the OPT.

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Follow Ups Full Thread

Topic - Output Tubes: Matching for Plate Current / Transconductance - rontokyo 05:10:33 12/09/06 (16)

If they are new tubes, - sser2 16:08:34 12/09/06 (6)

Re: If they are new tubes, - Jim McShane 09:19:16 12/10/06 (5)

Thanks for the correction. - sser2 13:05:30 12/10/06 (4)

Re: Thanks for the correction. - Jim McShane 14:01:31 12/10/06 (3)

I was thinking - sser2 14:51:29 12/10/06 (2)

Re: I was thinking - Jim McShane 15:06:58 12/10/06 (1)

I see. - sser2 16:15:25 12/10/06 (0)

so, hopefully, this explains why ... - Thom 08:47:02 12/09/06 (1)

Re: so, hopefully, this explains why ... - Jim McShane 10:48:42 12/11/06 (0)

Re: Output Tubes: Matching for Plate Current / Transconductance - lovetube 05:36:38 12/09/06 (6)

Re: Output Tubes: Matching for Plate Current / Transconductance - jcoe 14:38:41 12/09/06 (0)

Yes, I understand that it's important. But - rontokyo 05:44:43 12/09/06 (4)

Re: Yes, I understand that it's important. But - Jim McShane 06:39:21 12/09/06 (3)

Doesn't it depend on how the tubes are going to be used? - Ray Moth 13:42:40 12/09/06 (2)

Re: Doesn't it depend on how the tubes are going to be used? - Jim McShane 15:51:11 12/09/06 (0)

Clarification - Ray Moth 13:51:36 12/09/06 (0)

Follow Ups

Re: Doesn't it depend on how the tubes are going to be used? - Jim McShane 15:51:11 12/09/06 (0)

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