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Base 7S or 7AC
Phlogiston
Radio-Fixer-Upper
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City: Medford OR (OR what?)
#1

11-03-2017, 04:30 PM
Can anybody tell me the difference between the 7AC base (6L6) and the 7S (8417) base? Look the same to me.
 
I wanted to try some tube rolling on my new project and can't see why they speced the bases different.

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"I just might turn into smoke, but I feel fine"
http://www.russoldradios.com/
(This post was last modified: 11-04-2017, 12:23 PM by Phlogiston.)
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Ron Ramirez
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#2

11-03-2017, 08:00 PM
Agree, 7S and 7AC look the same to me as well.

Only, tube type 8417 is listed as having an 8LY base on my favorite online tube database, NJ7P.org?

Edit: Duncan Amps shows 8417 as having the same pinout as 6L6. I'm not familiar with the 8LY designation.

Edit #2: RCA tube manual RC-30 shows the 8LY designation as having pins 1 and 3 tied together (plate). Otherwise the same.
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Ron Ramirez
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Phlogiston
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Posts: 2,118
Threads: 112
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City: Medford OR (OR what?)
#3

11-03-2017, 09:57 PM
Ok. I see that now on RM. My 1966 RCA tube manual (25) does not list the 8417, so I got the base off of another site. I guess that site is wrong. Still I wonder why 7S and 7AC are drawn the same - and we might never know.

So I don't think that I'll try that tube.

Thanks
"I just might turn into smoke, but I feel fine"
http://www.russoldradios.com/
(This post was last modified: 11-04-2017, 12:24 PM by Phlogiston.)
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  1. The PHILCO Phorum
  2. Various and Sundry Categories
  3. Vintage Hi-Fi, Stereo and Audio