Got a B&K 467
 

And it came with 6 popular socket adapters, but for a CRT like the 21YP4B, none of the adapters fit. I have several tv's with this style pin setup. I know there are other adapters, and I just ordered setup data, but was just wondering if anyone had the info on a correct adapter? The number 6 adapter in the with the unit fits my Predicta which has that small pattern.

It should work with no adapter at all, just plug the tester directly onto the tube, set the G1 to 45 volts and G2 to one small division above zero, at least that's how my 466 works,

I picked up a Sencore CR 161 tester at this year's ETF convention and had the same problem with the socket--if I understand correctly. 21YP4 uses pin #6 as do other 12-L base CRTs and the socket would only accept 12-N bases. With mine it was a simple matter of drilling out the socket to accommodate the pin.

Is the 21YP4 an oddball then? I was assuming it was the same as most others.

Not exactly an oddball, but it is an electrostatic focus tube. So whereas 10BP4, 12LP4, 17CP4, 21AWP4 etc use only pins 1,2, 10, 11 & 12, the 21YP4 and many others also have a pin 6.

That particular CRT has a large button I will call it, that is in the center of the pins. It is alsolike the 21AUP4 and between the 2 CRT's, I have 5 of them. None of the adapters will even slide over that large button thingy. Incidentally, none of the color ones are large enough either.

Thanks guys for the replys. Found my Central Electronics RE-1 Rejuva-tube, and it fits the CRT's I described, and the unit still works fine. This thing is a dinosaur compared to the B&K, but it does what I need.