Some of you may have seen this picture tube listed on eBay. Well, I'm the one that took a chance on it.

It arrived safe and sound although the box is in rough shape.

http://farm6.static.flickr.com/5011/5500748723_bca75ac710_b.jpg

http://farm6.static.flickr.com/5219/5501342356_39f48d10b9_z.jpg

The only mark or label on the CRT is a "10X" written in marker.
Anyone know what this tube is ? Perhaps experimental ?

http://farm6.static.flickr.com/5138/5500748949_0dc11eaed8_b.jpg

I tried testing it as a 10BP4, but had to drop the bias from -52 to -36 to get the cutoff in the black box. It test very strong and has an excellent life test.
http://farm6.static.flickr.com/5254/5500749611_5af86db03e_b.jpg

Sure looks like an electrostatic focus gun to me, but no extra connection... focus element could be tied internally to the 1st anode (G2 in some nomenclature).
jr

It sure looks like it has some Xtra parts to the gun?

It sure looks like it has some Xtra parts to the gun?

It sure does. Here's a closeup of the gun.

http://farm6.static.flickr.com/5054/5501537492_b802b22909_b.jpg

Here's a 10BP4 for comparison.
http://farm6.static.flickr.com/5020/5500955413_99c48b2124_b.jpg

It sure appears to have a split second anode with a short focus element between the two sections, similar to the DuMont gun that I posted on another thread:

http://www.videokarma.org/attachment.php?attachmentid=169495&d=1298095247

I can't see if the focus is tied to the first anode, however. :scratch2:
jr

Q: How does the overall length compare two a 10BP4? It looks like the gun is pretty long.

I guess the next step would be to put it in a working set and see what happens?

It sure appears to have a split second anode with a short focus element between the two sections, similar to the DuMont gun that I posted on another thread:

I can't see if the focus is tied to the first anode, however. :scratch2:
jr

Q: How does the overall length compare two a 10BP4? It looks like the gun is pretty long.

It's actually about 1/2 " shorter than a 10BP4.

I guess the next step would be to put it in a working set and see what happens?

Sure thing. I suppose I'll have to put the focus coil off to the side if this CRT really does have electrostatic focus.

It's actually about 1/2 " shorter than a 10BP4.
Sure thing. I suppose I'll have to put the focus coil off to the side if this CRT really does have electrostatic focus.

Is it aluminized?

Cliff

Is it aluminized?

Cliff

Nope, but I wish it was.

I'd try it with the focus coil in place. I didn't have to remove the focus coil
when I used the 5AXP4 in my 16GP4 Zenith.

I pulled out one of my trusty Admiral chassis tonight and gave this CRT a try.

Here it is with a 10BP4 receiving a local LP VHF broadcast.
http://farm6.static.flickr.com/5177/5518634185_9197dfa40d_z.jpg

Here it is with the 10XP4 installed along with the same focus coil and dual-section ion trap magnet as the 10BP4
http://farm6.static.flickr.com/5131/5518634303_30da4fdd4f_z.jpg

I think the focus coil has to go.
Luckily, I had enough slack to slide it of the CRT and put it to the side.
http://farm6.static.flickr.com/5134/5519225360_5ae2a0e6d8_z.jpg

http://farm6.static.flickr.com/5178/5518634611_724c6fce5c_z.jpg

That definitely helped, but it was still a little fuzzy. Maybe a single section magnet would work better :scratch2:
http://farm6.static.flickr.com/5096/5518634821_49b16b7d90_z.jpg

http://farm6.static.flickr.com/5213/5518635037_93ff0d38bf_z.jpg

Yes, definitely. Not perfect, but I have a few magnets more I can try.
Just as soon as I can remember where I put them that is :o

I still have no idea what this CRT is all about, but it's bright and seems to be usable :)
http://farm6.static.flickr.com/5138/5518635253_6c00f6f814_z.jpg

http://farm6.static.flickr.com/5255/5518635479_47a93a8b77_z.jpg

Hi Bob…were you ever able to get this to work? I have the same brand, NIB CRT and I’m wondering if you made it a useable picture tube 10BP4 substitute

No, I never did anything more with it. I'm pretty sure it is supposed to be a drop in replacement for a 10BP4. Could be there is something wrong with mine.

I haven’t been able to get it to focus as a substitute in several focus coil TVs. Very similar smearing and soft focus you had. Same situation obviously with tested performance. It’s a magnificent tube and I tried it in my Admiral but couldn’t get it to focus with and without the focus coil. Weird

Maybe it is electrostatic focus. I don't recall if it has an extra pin for focus. If it does, it needs to be connected to ground or a few 100 volts.

That's a strange one. The 10XP4 doesn't appear in the EIA listing of registered tube types, so it appears to be a manufacturer's "in house" identification, and a datasheet is unlikely to be found.

Did you try moving the focus coil forward & back? Maybe focus field location different on that gun? Compare 12LP4 vs 12KP4, focus field differs by 3/4". Possible that tube was for a monitor?

Wasn't XP4 a common number for a test CRT? They were usually smaller though around 8".

5AXP4, 8XP4 and 8YP4 are the test CRTs.
There are other X CRTs like the 21XP4 which is regular TV picture tube.

The phosphor was poor applied as I recall which got me thinking it was a cheaply made generic replacement CRT. Would not surprise me if it is electrostatic focus hard wired to G2 internally.

Did you try moving the focus coil forward & back? Maybe focus field location different on that gun? Compare 12LP4 vs 12KP4, focus field differs by 3/4". Possible that tube was for a monitor?

I did along with the ion trap. Like Bob, I was able to get it close but it was still soft. I got this on eBay about 3 years ago and it was sold as a drop in replacement for a 10BP4 but, you know, you can say anything on eBay. It looks like a 10BP4, feels like a 10BP4, is pinned out like a 10BP4, is dag coated like a 10BP4...but it doesn't just drop in as a substitute.