does anyone know if you can use a 5bp4 as a sub for the 5tp4 used in the rca projection sets from 1949?

Not even close... The 5bp4 is a scope tube with electrostatic deflection an 2000 volts max anode voltage. The 5tp4 is a magnetic deflection tube designed for projection that takes 27,000 volts max on the anode to produce a very brite picture.

jt

any substitute or source of those crts?

I once had my hands on a 5AZP4, which uses a higher anode voltage, but has an integral HV lead.

Through the years I have often wondered if a tube with one letter difference could be at least usable as a replacement, but 9 times out of 10 it is out of the question. There are subs, or what could be used as subs with some circuit changes, but they sure don't go by the alphanumeric sequence. It would be nice if they did.

If you can ever get hold of a Sylvania or RCA tube guide from the 50s like I have, you will have an invaluable resource. I'm not so sure how hard they are to find these days.

If you need a projection tube Radioalguy has a couple.
http://www.radiolaguy.com/Tubes_CRTs.htm

any substitute or source of those crts?

Only sub for a 5TP4 is the harder to find 5AZP4

I've got a few loose ones, contact me off forum.

Chuck

And there is also the RCA 4820, also with an integrated HV lead, and another 40KV anode projection tube. I believe both the 5AZP4 and 4820 could be made to work in place of a 5TP4, thought the lower HV would diminish performance markedly.

A good way to find subs is to consult a period reference (or online posting thereof) and compare physical size of the envelope, deflection angle, type of focus, if it uses an ion trap, and electrical specks. If things are close enough or easily compensated for then it is likely to work

We have a good one posted:

http://www.earlytelevision.org/pdf/cbs_crt_specs.pdf

I want one of those 7", 75,000 volt projection CRTs :yes:

http://www.akh.se/tubes/htm/7wp4.htm

Wear your Dosimeter faithfully...

Wear your Dosimeter faithfully...

Just move into a cat-scan machine.....

I want one of those 7", 75,000 volt projection CRTs :yes:

http://www.akh.se/tubes/htm/7wp4.htm

WOW that is too cool. never seen that before. I want one too.

Here is a prewar one using 80kv:

http://www.earlytelevision.org/rauland_crt.html

No idea how the phosphor plate in that didn't melt at those voltages...

I just stumbled across a pre-war valentine card showing a projection TV :)
http://www.ebay.com/itm/J1474-c-1940-Pre-War-RCA-Mirror-Reflection-Television-Vtg-Diecut-Valentine-Card-/331126783657

http://www.videokarma.org/attachment.php?attachmentid=181759&d=1392244241