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Old 26th September 2011, 10:38 PM   #1
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I am designing an amplifier using this 6L6 datasheet.
6L6-GC pdf, 6L6-GC description, 6L6-GC datasheets, 6L6-GC view ::: ALLDATASHEET :::

The amplifier will be running AB1. The column I am using on the datasheet is for 26.5 Watts. I am trying to use the tube curves to determine the gain of this push pull stage, but none of the curves are based on the 270 V screen voltage. One set of tube curves is based on 250 V of screen voltage, but the operating point doesn't line up due to the screen voltage. Can someone help me figure out the gain of this stage please? It is the missing link for my amp.

Nobody replied to my last post earlier. I'd really appreciate someone replying, or is this question too easy to be answered and I'm simply just an idiot?
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Old 26th September 2011, 10:47 PM   #2
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I ll reply!

250 to 270 = almost no difference. Just a little more G2 current and a little more power. Proceed as you planned!
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Old 26th September 2011, 11:23 PM   #3
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Originally Posted by costis_n View Post
I ll reply!

250 to 270 = almost no difference. Just a little more G2 current and a little more power. Proceed as you planned!
Thank you man. I could not get anyone to answer my question. If wouldn't mind answering one more, for my G2 resistor, would I be using the zero signal screen current and the voltage drop across the G2 resistor to find its value?
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Old 27th September 2011, 12:14 AM   #4
Gilgy is offline Gilgy  United Kingdom
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Did we really need this thread three times?

6L6 AB1 question. Please help.

6L6 AB1 question. Please help.
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Old 27th September 2011, 01:45 AM   #5
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Originally Posted by grungeman91 View Post
I am trying to use the tube curves to determine the gain of this push pull stage...
Why make it harder than it needs to be?

P= V^2 / R

V= sqrt(P*R)

V= sqrt(26.5 * 6600)= 418.21Vrms

Vp-p= sqrt(8) * Vrms

Vp-p= sqrt(8) * 418.21= 1182.88Vp-p Across the whole primary

Vi= 45Vp-p

Av= 1182.88 / 45= 26.29 On primary side, across 6K6

If using Rl= 8.0R:

Zn= 6600 / 8= 825 : 1 (Pri : Sec)

Vn= sqrt(Zn)= sqrt(825)= 28.72 : 1 (Pri : Sec)

Av`= 26.29 / 28.72= 0.92 (Across Rl= 8R)
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Old 27th September 2011, 04:00 AM   #6
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Section 6 of the radiotron designers handbook fourth edition explains how to calculate the unpublished characteristics. You can download from pmillet technical books online.

Alfredo
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Old 27th September 2011, 08:14 AM   #7
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Quote:
Originally Posted by Gilgy View Post
Did we really need this thread three times?

6L6 AB1 question. Please help.

6L6 AB1 question. Please help.
If nobody bothers to reply, sure we did.
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Old 27th September 2011, 08:51 AM   #8
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patience is a virtue. 24 hours is not an unreasonable amount of time to wait when people (often highly qualified and busy and incredibly knowledgeable people, far better experienced than me) are giving a reply...

Impatience also looks whiney. Maybe not in this case, but in others I've noticed
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Old 27th September 2011, 09:15 AM   #9
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Did this spreadsheet a few yeras ago http://www.revintage.se/PPABAMP.xls . For only outputstage gain set PI gain to 1. It is based on loadmatch3-pp-triodes
You will arrive at in the ballpark of Miles figures though. To simplify his calculations you can easily make a spreadsheet for that too.

Last edited by revintage; 27th September 2011 at 09:17 AM.
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Old 27th September 2011, 03:48 PM   #10
kevinkr is offline kevinkr  United States
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We don't need three threads on this topic. In the future please bump the existing thread if you are not getting a response. I have merged the single response from the other threads into this one and deleted those threads..
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