C carldoc Well-Known Member Joined Mar 27, 2012 Messages 101 Reaction score 2 Jul 18, 2004 #1 When viewing the plans for the Mark II, I noticed that it uses a bt-30 tube. Can I get away with using a bt-20 tube instead or is there that much of a variation in diameter
When viewing the plans for the Mark II, I noticed that it uses a bt-30 tube. Can I get away with using a bt-20 tube instead or is there that much of a variation in diameter
sandman Well-Known Member Joined Jan 17, 2009 Messages 10,563 Reaction score 20 Jul 18, 2004 #2 A BT-20 is 0.735" in diameter and the short lived and now OOP BT-30 was 0.765". Also the BT-30 was not spiral wound but parralel wound but a little thicker. Nobody can see the difference really. sandman
A BT-20 is 0.735" in diameter and the short lived and now OOP BT-30 was 0.765". Also the BT-30 was not spiral wound but parralel wound but a little thicker. Nobody can see the difference really. sandman
