I see a number of CRT testers that will test the 8JP4 and some sites that sell 8JP4 test adapters. Yet I don't know of any sets that use this CRT and I can't find any specifications for it.

Is this the same as a 7JP4 but only 8" in diameter?

John Y.

My Motorola 9VT1 uses the 8" equivalent of the 7JP4 which is the 8BP4. Electrically it is the same tube only with an 8" screen. I've never seen an 8JP4.

I don't recognize the 8JP4... I'm out of town, or I'd consult the RCA Receiving Tube Manual. Compucat is correct about the 8" Motorola electrostatic sets using the 8BP4.

Charles

I did look in the RCA manual, and an old Sylvania CRT manual and it's not listed there.

It's on the chart of the B&K 467 CRT tester and a test adapter is listed at oldradioparts.com for it.

http://www.bkprecision.com/support/downloads/pdfs/CRT_Setup_Chart.pdf

I don't need to know. It's just to satisfy my curiousity.

John

Since an 8BP4 is essentially an oversize 7JP4, it may be that references to an 8JP4 are merely "typos by suggestion". I can't tell you how many times on various skizzies and tube location charts I've seen the 6BC5 referred to as 6CB5 thanks no doubt to associating it with 6CB6.