[Boatanchors] E.F Johnson calibrator 250-28 tube?

[Glen Zook]

The 6BH6 and 6AU6 are very similar tubes.  The basic
difference is that on one tube the internal shield is
connected to pin 2 and on the other it is connected to
pin 7.  The cathode is connected to pin 7 when the
shield is connected to pin 2 and the cathode is
connected to pin 2 when the shield is connected to pin
7.  Since both these pins are usually grounded then it
really doesn't matter which tube is used.

Even if there is a resistor to ground from the cathode
the tubes will often still work as an oscillator if
the circuit was originally designed for just one of
them.

Glen, K9STH


--- telegrapher at att.net wrote:

Well what a fine show this is.  Now, which tube is
correct?  The 6BH6 or the 6AU6.  Or maybe different
versions or some were modified?  Who dreams up this
stuff anyway?  It's to close to Christmas.
 
I don't have one of these but i've run into the same
thing with a couple of my radios. One manual says one
tube lineup and another manual says another tube
lineup.  What fun, yes?









Glen, K9STH

Website:  http://k9sth.com


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