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Why is there 34v on pin 1?

PostPosted: Sat Apr 09, 2016 3:23 pm
by gavinhaley
On every pinout for every version of 6L6 I can find there is not connection on pin1 yet on the Clementine voltage sheet it shows 34v on pin1. The cathode voltage obviously, but why? I just ordered some metal 6L6s to give a try is the reason I am asking.

Re: Why is there 34v on pin 1?

PostPosted: Sun Apr 10, 2016 4:35 pm
by Geek
Hi,

I don't have a PCB in front of me, but it is accepted practise to tie pins 1 and 8 together with this pinout series of tubes as some types, like the EL34, have their surressor tied to Pin1 and is usually held at cathode potential.

Cheers!

Re: Why is there 34v on pin 1?

PostPosted: Sun Apr 10, 2016 4:43 pm
by battradio
To use an EL34 pin 1 & 8 would need to be connected together . With a metal 6L6 there would be 34 volts produced by the cathode current of the tube across the cathode resistor on pin one and the metal shell of the tube in this case .
A KT66 has an internal connection between pin 1 & 8 .

Re: Why is there 34v on pin 1?

PostPosted: Tue Apr 12, 2016 10:51 am
by TomMcNally
Here is Shannon's note from the order / parts list / manual page on the forum:

Also note that some old 6L6s need pin 1 and pin 8 to be jumpered together, as they are not internally connected. Go ahead and add them to V2 and V3 after you solder the socket in place. It can double as a cathode bias test point clip and permits EL34s to be used

Re: Why is there 34v on pin 1?

PostPosted: Tue May 17, 2016 6:15 pm
by TomMcNally
Here's what happens to Russian 6n3c-e tubes if you don't jump pins 1 and 8 together ... some music, some pops, some smoke, some smell, bright blue glow! Good reminder.