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26th September 2011, 10:38 PM  #1 
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Join Date: Aug 2010

Please Reply
I am designing an amplifier using this 6L6 datasheet.
6L6GC pdf, 6L6GC description, 6L6GC datasheets, 6L6GC 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? 
26th September 2011, 10:47 PM  #2 
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Join Date: Aug 2008

I ll reply!
250 to 270 = almost no difference. Just a little more G2 current and a little more power. Proceed as you planned! 
26th September 2011, 11:23 PM  #3 
diyAudio Member
Join Date: Aug 2010

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?

27th September 2011, 12:14 AM  #4 
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Join Date: Oct 2009

Did we really need this thread three times?
6L6 AB1 question. Please help. 6L6 AB1 question. Please help. 
27th September 2011, 01:45 AM  #5  
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Quote:
P= V^2 / R V= sqrt(P*R) V= sqrt(26.5 * 6600)= 418.21Vrms Vpp= sqrt(8) * Vrms Vpp= sqrt(8) * 418.21= 1182.88Vpp Across the whole primary Vi= 45Vpp 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) 

27th September 2011, 04:00 AM  #6 
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Join Date: Jan 2008
Location: Southern California

Section 6 of the radiotron designers handbook fourth edition explains how to calculate the unpublished characteristics.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 
27th September 2011, 08:14 AM  #7  
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Join Date: Aug 2008

Quote:


27th September 2011, 08:51 AM  #8 
diyAudio Member
Join Date: Mar 2007
Location: Auckland, NZ

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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27th September 2011, 09:15 AM  #9 
diyAudio Member
Join Date: May 2007

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 loadmatch3pptriodes
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. 
27th September 2011, 03:48 PM  #10 
diyAudio Moderator

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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