Steve my CRT

[Harry Dalek]

Steve heres the measurements to the crt you asked about it may be a mm off here and there ....
eyes not good
Have a great holiday

[Steve Anderson]

Harry, could you double check a few things on this CRT...

The total overall length...

If all pins were fitted there would be 14 of them?

Does it have a single connection up near the screen end of the tube similar to the attached CRT illustration?

The example is one of the possibles IF your tube has that connection on the side. Whatever, do not use this datasheet for your CRT until we're sure.

Steve A.

P.S. This is no holiday! It's real work!

[Harry Dalek]

Hi steve

Harry, could you double check a few things on this CRT...


No worries will do !

The total overall length...

I will check this again steve is it display screen to end of the tube

If all pins were fitted there would be 14 of them?

Its 12 2 pins are numbered but nothing there just rased plastic ,i'll take a photo later .

Does it have a single connection up near the screen end of the tube similar to the attached CRT illustration?

No anode connection think thats as i recall on of the pins on the plug.

The example is one of the possibles IF your tube has that connection on the side. Whatever, do not use this datasheet for your CRT until we're sure.

Well no nothing there Steve but does look like it apart from that!

Steve A.

P.S. This is no holiday! It's real work!

Thats no good !!!!

Harry

[Steve Anderson]

OK Harry, when you have the time. If there is no side-connector up near the screen the chances are that the CRT will require under 1500V, often (mostly) under 1000V. Which for our application is fine.

The missing pin(s) will probably have some indication of 'where they are not' by something as you say, a raised 'bump' in the base moulding.

Yep, the tubes total length from centre of screen/faceplate to the end of the pins or keyway, whichever is longer. i.e. if you stand it on its face (carefully) how tall is it in total, everything included?

It's obviously a 3" CRT and if it has no final anode connector near the screen end all we need to know is how many pins (including those missing?). They're always on a regular angular spacing (including the missing ones).

A photo will clear it up.

Steve A.

As for the work, I think I'm gonna quite enjoy this project. I'm working (for once) with professional broadcasters who have knowledge, experience and simply know what they're doing. They also have a decent budget, so it's NOT the BBC! (Thankfully)

[Harry Dalek]

OK Harry, when you have the time. If there is no side-connector up near the screen the chances are that the CRT will require under 1500V, often (mostly) under 1000V. Which for our application is fine.

The missing pin(s) will probably have some indication of 'where they are not' by something as you say, a raised 'bump' in the base moulding.

Yep, the tubes total length from centre of screen/faceplate to the end of the pins or keyway, whichever is longer. i.e. if you stand it on its face (carefully) how tall is it in total, everything included?

It's obviously a 3" CRT and if it has no final anode connector near the screen end all we need to know is how many pins (including those missing?). They're always on a regular angular spacing (including the missing ones).

A photo will clear it up.

Steve A.

As for the work, I think I'm gonna quite enjoy this project. I'm working (for once) with professional broadcasters who have knowledge, experience and simply know what they're doing. They also have a decent budget, so it's NOT the BBC! (Thankfully)

Hi Steve

12 pins but those spaces are numbered so 14 1 2 3 4 5 6 is nothing then 7 8 9 10 11 12 and 13 is nothing.

25.5 length

Yes no Anode connection at all its all from the pins at the base .


If you manage to find out what it is it will be very useful thanks for the help !

Good luck for work as well

[Steve Anderson]

OK Harry,

14 pins with pins 6 and 13 missing...a total of 12 pins actually present.

25.5cm length, and we already know it's a 3" CRT. You'll probably find the heater between pins 1 and 14, i.e. each side of the keyway. It will probably read very low Ohms as the heater is cold, but not a dead short. But if you find an open circuit, don't worry as a few CRTs did use other pins. Final anode is in amongst those 12 present pins, not on the side of the bulb.

With that we should be able to narrow it down to get if not an exact type, but enough data to get it going. Most CRTs of this type used similar voltages which are not critical except the heater volts of course, and almost industry-standard pinning...but as ever, not always.

Give me a little time over this weekend and I'll have a weed through the database of CRTs I have.

Steve A.

Later...seems that this is your baby, few meet the dimensions, pin arrangement, but more important is none were as popular as this CRT. The 3BP1.

It's towards the upper-end of the voltage range I mentioned, and at the upper end where any more (say 2000V) required a side-contact, especially at altitude in unpressurized aircraft.

Datasheet attached.

[Harry Dalek]

OK Harry,

14 pins with pins 6 and 13 missing...a total of 12 pins actually present.

25.5cm length, and we already know it's a 3" CRT. You'll probably find the heater between pins 1 and 14, i.e. each side of the keyway. It will probably read very low Ohms as the heater is cold, but not a dead short. But if you find an open circuit, don't worry as a few CRTs did use other pins. Final anode is in amongst those 12 present pins, not on the side of the bulb.

With that we should be able to narrow it down to get if not an exact type, but enough data to get it going. Most CRTs of this type used similar voltages which are not critical except the heater volts of course, and almost industry-standard pinning...but as ever, not always.

Give me a little time over this weekend and I'll have a weed through the database of CRTs I have.

Steve A.

Later...seems that this is your baby, few meet the dimensions, pin arrangement, but more important is none were as popular as this CRT. The 3BP1.

It's towards the upper-end of the voltage range I mentioned, and at the upper end where any more (say 2000V) required a side-contact, especially at altitude in unpressurized aircraft.

Datasheet attached.

Hi Steve

Thanks heaps for that ! it sure looks like its the right one ! Ok sounds like the thing was used in planes interesting !

2000v i think i need EHT circuit for this one but not sure if you can hook them up to those resistors like that ? making a transformer power supply is a little ify that high i would hope an eht circuit would work .

Thats really good have the pdf of it Steve makes once i get around to playing with it so much easier ...! Thanks again !!!

[Steve Anderson]

Harry, no problem. It doesn't need 2000V, it is specified at 1500V in that datasheet and I suspect for slow-speed applications like NBTV 1000V will do the job, perhaps even less...but the trace starts to become a bit too dim and the focus suffers.

But if you use the circuit within the datasheet you just vary the final (maximum) voltage anywhere from 700 to 2000V, all the others adjust themselves to suit...the focus may need a tweak. A simple modification to the grid circuit will allow modulation.

Steve A.

[Harry Dalek]

Harry, no problem. It doesn't need 2000V, it is specified at 1500V in that datasheet and I suspect for slow-speed applications like NBTV 1000V will do the job, perhaps even less...but the trace starts to become a bit too dim and the focus suffers.

But if you use the circuit within the datasheet you just vary the final (maximum) voltage anywhere from 700 to 2000V, all the others adjust themselves to suit...the focus may need a tweak. A simple modification to the grid circuit will allow modulation.

Steve A.

Hi Steve

Oh ok i will look into that so i need to look at making a 1.5kv power supply having the correct schematic to run the thing is like gold .
It will make me try it out sooner than later for sure .
Thanks again for finding it !!!