I have a an old Philco that has 6 pin tubes. Is there any way to test them with my Hickok 6000 tester?
It doesn't have the right size receptacle.

The pedestal where the sockets are mounted came in two different formats in the 6000 series, older tubes and more modern, so the tester is certainly capable of measuring both ages of tubes. Something, in fact, keeps tickling in my brain that there was even a plug in adapter pedestal available. A little analytical thinking and tracing through the switching schematic should yield a way to make up a quick and dirty adapter that uses an octal base and 6 pin socket. Surely someone has done so and can chime in to guide you. I don't have enough experience yet to confidently tell you how. Sorry.

Yes, you'd need to make an adapter with a 6-pin socket and octal plug. Pin 1 to pin 1, 2 to 2 and so on. And then find the obsolete data book for the 6000, which is probably online somewhere.

Make one. Solder wires to a six pin socket. Insert wires into pins of old octal tube base. Ohm check that no pins are shorted together. Then glue socket to base. Solder protruding wires to base pins. Clip off extra wire. You may have to do a little trial and error fitting to find sockets and tube bases that work well together. You can trim the socket connectors some if they're too long.

The adaptor is wired straight through: 1 to 1, 2 to 2, 3 to 3, etc. Though no such 6000 model exists, all the old (6000) and new (6000A) sockets are shown on one schematic. In this case you won't be using pins seven and eight of the octal socket.....

I've made 4,5,6, and 7 pin adaptors for my 6000A which work fine. The tube data is covered in three books: something like old, current , and foreign, somewhere on-line.

6000 data here: http://www.stevenjohnson.com/hickok/data.htm