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A WE-91B project
A WE-91B project
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Old 10th January 2018, 05:07 PM   #11
TheGimp is offline TheGimp  United States
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I believe it is actually NFB due to the way it is feed back to the screen instead of the grid, and taken from the plate of the output tube.

Note 7 seems to confirm this in stating that shorting the 70K feedback resistor results in 10dB less gain. Shorting the 70K feedback resistor allows more feedback.
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Old 10th January 2018, 05:20 PM   #12
Koonw is offline Koonw
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I have edited for you, but you can do even better :-). This is really a very hot amp dispite the NFB inplace.
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Old 11th January 2018, 01:22 AM   #13
jerrylong is offline jerrylong  China
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Thank you very much. Your correction is really helpful. Giving me more confidence to finish this project
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Old 11th January 2018, 09:40 AM   #14
jazbo8 is offline jazbo8
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A WE-91B project
Quote:
Originally Posted by TheGimp View Post
I believe it is actually NFB due to the way it is feed back to the screen instead of the grid, and taken from the plate of the output tube.

Note 7 seems to confirm this in stating that shorting the 70K feedback resistor results in 10dB less gain. Shorting the 70K feedback resistor allows more feedback.
Oops, you are right.
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Old 12th January 2018, 07:28 AM   #15
jerrylong is offline jerrylong  China
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the Power Trans design:
10.JPG
a=38mm(EI-114),b=55mm

Prim:
220V~472T/0.54mm
230V~494T/0.54mm
Sec:
420V(1010T/0.285mm)~400V(962T/0.285mm)~0~400V~420V/160mA
5V/2.5A(12T/1.129)
2.5V(6T/1.129mm)~0~2.5V/2.5A
5V(12T/1.129)~0~5V/2.5A
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Old 12th January 2018, 07:42 AM   #16
jerrylong is offline jerrylong  China
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The choke design:
10.JPG
EI-96
a=32mm, b=35mm

3500T/0.31mm
L=20H
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Old 12th January 2018, 07:54 AM   #17
jerrylong is offline jerrylong  China
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The OPT design:
11.jpg

Prim:2400T/0.33mm
Sec:0~4ohm(88T/0.55mm*3)~8ohm(123T/0.55*3)

Last edited by jerrylong; 12th January 2018 at 08:08 AM.
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Old 12th January 2018, 07:56 AM   #18
davorin is offline davorin  Croatia
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Air Gap?
L=16H for Idc-max=?
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Old 13th January 2018, 05:19 AM   #19
jerrylong is offline jerrylong  China
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It is really hard to find these 2 16uf capacitor, is it OK to use 20uf/450V to replace?
12.JPG

13.JPG
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Old 16th January 2018, 01:22 AM   #20
jerrylong is offline jerrylong  China
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chassis design
20.JPG
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