I have a wonderful Military 550X Hickok tester and would like (need) to add a 9 pin socket or adapter to test 12AX7's, etc. I need to see a schematic, or scribble of some kind to wire in the socket or run a plug from an octal socket to an outboard 9 pin socket. Any one done this? and any help really appreciated.

Thanks, Dale

These files will get you started.
The tube Data for the I177 and the 550x is the same?.

The MX-949/U is a tube socket adapter for the I177 that should work on the 550X.
Are use it to build a 9 pin socket.

http://radiorestorer.com/hickok510x.PDF

http://bama.edebris.com/manuals/military/i177/

The grid signal of the 550X can kill a 12AX7.

Jimmie

Thanks, Jimmie...About $500 is a bit too steep, but with the schematic I might be able to reproduce the adapter or at least most of for my use.

Cheers, Dale