Funky National branded 7199 tube

by Sal Sun Jun 07, 2009 12:17 am

Sal: Posts : 221
Join date : 2009-02-05
Location : Central New Jersey Dynaco-ST70.com

Post n°1

Funky National branded 7199 tube

by Sal Sun Jun 07, 2009 12:17 am

This week I received a ST-70 to rebuild. In testing the tubes I found this funky National 7199 tube. Its probably a 6U8 or a 6GH8 with attached printed circuit board swapping the 3 pins.

Did you ever see such a tube? You can see on the top photo the original tube pins are offset to the new pins on the pcb.

Regards,
Sal

Funky National branded 7199 tube National7199

Funky National branded 7199 tube National7199

by GP49 Sun Jun 07, 2009 1:33 am

GP49

GP49: Posts : 792
Join date : 2009-04-30
Location : East of the sun and west of the moon

Post n°2

Re: Funky National branded 7199 tube

by GP49 Sun Jun 07, 2009 1:33 am

Never have seen one but I like the circuit board...

by **Bob Latino** Sun Jun 07, 2009 10:35 am

Bob Latino

Bob Latino: Admin; Posts : 3271
Join date : 2008-11-26
Location : Massachusetts

Post n°3

Re: Funky National branded 7199 tube

by Bob Latino Sun Jun 07, 2009 10:35 am

Yes - that small board looks like a custom made 7199 to 6GH8 adapter. As most Dynaco users know there is no direct replacement for a 7199 tube although a 6GH8 or 7687 tube may be used in it's place if a pin adapter is used. Both the 7199 and the 6GH8/7687 have similar characteristics and the the pin out is the same on the triode section on both tubes. The pentode section, however, has a different pin out. Since the 7199 tube is not made any more and as the remaining supply of these tubes slowly dries up, these adapters will become more common. See below for the pentode section pinout differences between the two tubes.

Bob

Funky National branded 7199 tube 7199_7687