K2-R schematic with 6AN8 extracted by Achim Dassow. The output tube is a probably 6AN8 triode pentode. Another version of the K2-R used a 6X8, as pointed out by Bob Pease in the RS power supply. (9-14-8)
The K2-R can also be found in the RK-200 power supply, as pointed out by Achim Dassow.
Bob Pease clarifies the two versions of the K2-R in an email to me and Achim Dassow:------------------------------------------------------------
Date: Thu, 14 Aug 2008 13:25:42
Hello to Joe and Achim,
Here are the schematic and notes on the Model RS. Not to be confused with the SR-400 or R-300 or R-500 (or the 6033 or the PR-15-150 or PR-300 at lower voltages.) Copied from an old 1955 Mimeographed Data Sheet. Now just over 53 years old.
Aha. The 6X8 is very similar to the 6AN8 but in a 9-pin bottle, it has a SEPARATE pin ( pin 1) so you can bias the Suppressor Grid separate from the Cathode. And the cathode is common to both the triode and the pentode, at pin 6. See at: http://www.nj7p.org/Tube4.php?tube=6X8
The 6AN8 has separate connections to the two cathodes at pins 3 and 9, and the suppressor grid is tied internally to pin 9. The K2-R for which you drew the schematic is designed to go with the 6AN8 and NOT with the 6X8. So at one time there may have been TWO different versions of K2-R, one compatible only with the 6X8, and the other only with 6AN8.
Have fun!! / Best regards. / rap
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