Porthole on Goodwill Auction also RCA
 

Zenith with busted CRT

http://www.shopgoodwill.com/viewItem.asp?ItemID=2444733

RCA

http://www.shopgoodwill.com/viewItem.asp?ItemID=2444914

Shame they busted the CRT on that zenith. Looks like the 16GP4 too :tears:

That set uses a 16EP4. Good luck finding one of those.

It had a brightner on it anyway so it probably was bad prior to getting busted.

Is this a metal/glass composite tube and would a 16AP4 sub it?

It is a metal/glass tube.

The 16GP4 is a 70 degree tube
The 16EP4 is a 60 degree tube
The 16AP4 is a 52 degree tube

The 16A is a better choice electrically, but if I remember right it is ~3 inches longer. The 16G is a better choice physically, but electrically you'll need another 10 degrees deflection. I subbed a 16G in a *sick* 1950 Zenith, and I kinda got the feeling that it will work. I have a pal who's restoring a 1949 Zenith, and he needs a 16EP4 also. If he uses the longer 16A, he may have to leave the back off of the set. When he finishes the chassis restoration, I'll post whether a 16G subbed OK or not.