Test CRT: How to Select and Use?

[Jon1967us]

So, I'm considering finding a CRT, such as a 8YP4, that was manufactured for testing purposes. Besides filament voltage and perhaps deflection angle (?) What do I need to look for to match a "test tube" to a chassis?

What are the advantages/benefits of using one?

[bandersen]

There are basically only three test CRTs
5AXP4 is for the earliest sets with a round CRT, low deflection angle and big 12 pin base.

Next came the 8XP4. It is for the 50s rectangular CRTs with 70 or 90 degree deflection and big 12 pin base.

Finally, the 8YP4. It's for the newer rectangular CRTs with 110 degree deflection and small base.

All are 6.3 volt, 0.6 amp filaments. Auto focusing and no ion trap magnet required

[Jon1967us]

Thanks.

And I'm assuming all that is needed is to throw the yoke, HV anode and plug on and you're good to go?

I seem to remember maybe one of your vids showed you using one...or am I smoking?

[Electronic M]

You can use the 8X inplace of the 5AX the raster won't fill the screen and the image will be a ~4" circle in the center. In most sets it will be plug and play. Some portables may have lower current and different voltage heater strings which may effect heater performance of the test CRT.

Telematic made an 8X test jig I (and others) have that consisted of the test CRT a test yoke with long alligator clips with inline fuses, HV extension lead (mines missing), adapter sockets for various basesand CRT base extension cable (with this jig you could use an 8X on sets meant for an 8Y if you used the jigs yoke), a test speaker and audio output transformer....all in a nice carrying case.