7BP7 CRT Question

[Rusty34]

I recently purchased a TRK-12 from another collector and he advised me the set came with two 7BP7 CRT's when he bought it at the estate auction of Dick Scovell many years ago. Mr. Scovell had been the lead camera man for CBS from 1949 - 1972 and he restored this television to working order. My question is, why would Mr. Scovell have kept a pair of 7BP7's with this television? One of them is a NOS Raytheon in the original box.

[Electronic M]

According to this page: https://en.wikipedia.org/wiki/Phosph...phosphor_types it is a radar tube with blue phosphor with yellow persistence.
It would probably suck for TV usage. Maybe he wanted to build an oscilloscope or something.

[Polaraligned]

Yeah, a 7BP7 would never be used in a TV.

[jr_tech]

If he also had a 621, the 7BP7, which uses magnetic deflection and focus, could be made to function in that set... a blue filter could be used to remove the yellow-green long persistence component, leaving a blue image, which might be semi-watchable. Since 7DP4s are fairly scarce, blue is better than nothing.

jr

[N2IXK]

P7 is a dual layer phosphor used primarily in radar. It has a very short persistence blue/white rear layer which is excited by the electron beam, and a very long persistence yellow layer in front, which is excited by the blue light from the rear layer. It gives a bright blue flash of light, followed by a slowly fading yellow afterglow. Pretty unwatchable for regular TV.

About the only TV application would be monitors for Slow Scan TV reception. A lot of radio hams played around with this, and many 7" electrostatic sets were converted to slow scan service back in the day....

[Robert Grant]

For a few years, I was using an Apple/// computer monitor(standard NTSC scan rates, only with P1 Green phosphor, medium persistence).

It definitely improved my ability to read call letters on the screen.