Color VS black and white is usually fairly easy to visually discern. Color usually has 3 guns arranged in a delta, except for later inline guns. There's basically always 3 heater cathode assemblies in color regardless of inline or delta so that's another easy identifier.


Almost certainly not in this case. The getter on an uninstalled gun is typically a solid chunk of metal. After installation it's "flashed" (induction heated to vaporization) and the vapor film that deposits on the glass is what forms the actual getter. As long as there's enough solid material present to flash it's probably fine if the surface has been exposed to air for a while. They certainly don't make new gun assemblies in a vacuum chamber. They're always in air until they go in a CRT. It's exposure to air after installation in the tube post flashing and cathode activation that's a problem for guns.

I plan on going back for the October swap meet and will take a much closer look at the inventory and document with photos and video. All I can say for sure is the guns I did see were small, likely more modern B&W and had that loose powder.

Thanks for offering to do that. I'm hoping by October we'll have a good idea of what kind of shape the equipment is in and how good we are with manipulations. I hope we can find some guns appropriate for 10BP4 and 12LP4 tubes but since they are the oldest magnetic focus commercial CRTs, the availability of NOS guns is probably scarce.

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Back in the day, we usta buy (color) rebuilts from a local rebulder in Phoenx. The jugs almost always arced. We had a tool we called the "cattle prod" for clearing arcs. Damned if I can remember what it's called. Some kinda "coil", but not Tesla coil. It was line-operated, and shaped like a very large Dremel tool, with a prod sticking out the end. We would stick the prod to the end of the jug and shoot the juice to it until all the incandescent debris quit flying around inside and stuck somewhere. The treatment was very effective and the jugs gave good service.
Cleanliness would need to be a major objective in any rebuilding endeavor.

Does anybody remember the name of that tool? Looked all over the interweb and can't find it.

See this video of Scotty at Hawkeye applying the high voltage at 1:16:00 and following.
No name is given for the device except a high voltage transformer.

https://www.youtube.com/watch?v=PFnWYe5MzrY

I also seem to recall a name attached to the handheld device you're describing, but I don't remember it, even though we had one in the lab at Zenith.

Is this hand held Tesla coil what you were thinking of?

https://www.arborsci.com/products/te...n=76ed39d3225f

Lol, beat me to it. BD-10 high frequency generator? https://www.electrotechnicproducts.c...ncy-generator/

Thanks. Yeah, looks like it, 'cept ours was a bit bigger and sounded like it had a mechanical interrupter driving the primary, like a Model T spark coil on steroids.

3 phase motors can be run from single phase supplies using variable frequency drives. Here's a random example from googling "3 phase vfd": https://www.ebay.co.uk/itm/144979535330?_ul=GB

Is that like a sonicator? I have 2 of them. I’m sure they won’t be applicable for this work but we use them to lyse cells. If you immerse the tip in water, the liquid will get hot. Terrible noise

Most certainly. We've installed several of these over the years where only single phase power is available. They work very well, but cost $$$

Hi folks. I misunderstood Jerome’s instructions regarding what and what not to post from private conversations so I removed the post, or at least scrubbed it of everything.

There was a quack medical device called "Violet Ray" that was a small HV operated hand held HV transformer with some kind of buzz coil in it that (it originally would drive a light up gas tube) some collectors use them to check for gas in early color CRTs (they replace the tube with a metal spike) but from having one I can tell you that some good non-gassy tubes light up just like bad known gassy ones do so it's not a spectacularly accurate test.

The basic 10BP4 guns were carried through into the mid 50s when magnetic focus slowly disappeared. It should be possible to rebuild with an electrostatic focus gun and remove the focus coil from the neck area of the TV and have a usable tube....Vice versa you could add a PM or EM focus magnet and make what originally was a electrostatic focus tube work in the same set with a new magnetic focus gun.

Both the 10BP4 and 12LP4 are common enough (just about everything used them for the better part of 4 years and broadcast monitors used compatible types into the 60s) that supply shouldn't dry up any time soon (there are enough low desirability models out there with ruined cabinets as donors) but on the flip side there are many oddball screen sizes that were only used in a few sets where it a tube isn't on a shelf somewhere you might have to wait years for a replacement.

At risk of repeating myself I believe the way forward on the gun issue is to source new heater-cathode and getter assemblies and weld them to existing guns. This is what RACS did on the 15GP22 they rebuilt since a replacement gun wasn't available then. While it's a little fiddly getting grid cathode spacing right (and possibly cathode diameter) and there would be some learning curve spot welding, it's far simpler and there's far fewer variables than making a new gun and it doesn't present the challenge of requiring a maker to either find lost documents or reverse engineer an old gun.

NOOOO! :tears:

They did not follow up on if that rare 19vp22 made it or not! :P

I spoke with Nick last night (Wednesday 6/11/2025) via email. He believes current efforts should be focused on obtaining guns.

Several thread contributors have mentioned they might be able to help out with this. I guess my task is to focus on and coordinate these efforts and Nick seems ready to take it from there.

Just want to touch on this again so it doesn't fade away. After several email exchanges with Nick, he is sure he has the equipment functioning and will be able to rebuild, at the least, B&W CRTs. I assume this will mean 10BP4 and 12LP4 tubes for starters. The issue is guns. If you have ideas, access to or reliable sources, it would be great if you would at the least begin the process of initiating outreach. I know several folks had knowledge of available guns and said they would check quality and numbers. I have no reason to doubt Nick's sincerity and his assessment of the state of the equipment. I think we need to get him some guns! :pistols::pistols::pistols:

Cool, but much, much bigger demand for 21FDP4s for Predictas.
Smaller diameter neck / smaller gun.

Not sure if there are more smaller or larger guns left around. When I was at the ETF last, I only saw one box of flaired neck glass for 10BP4 diameter. Over a dozen boxes of smaller diameter. Will take a detailed inventory of the guns next time I'm there.

Are these the disaster low voltage tubes from the Holiday model? I just sold mine for close to $2K with a bright beautiful 2.68 volt CRT. Very special I'm told to have one in like new condition. I asked for and got a price I hope reflects its rarity. Alas, I have another with a dead tube. Would any of the guns you're talking about or you know of be appropriate for the 17" Predicta tubes? I have 3 Seventeeners with very dim CRTs.

Yes, Holiday, Pedestal, Tandem and Continental models.
Also, many other brands used compatible CRTs - GE Coaxial, Sylvania Halolights for example. Generally speaking 21", 110 degree deflection, short neck CRTs are very much in damand. Used, strong going for around $300-$500. NOS, name your price.

The original Philco 12EAP4 was 2.35 volts. The recommend replacement 21FDP4 is the standard 6.3 VAC. I asume rebuilds would also use 6.3 volt guns.

That's right 2.35V. Thank you.

Just want to put this thread up at the top of the list again. I have not spoken with Nick in a couple of months but my last communication was he's waiting for guns to begin rebuild trials. My guess is we're going to need to inventory what's available at a level of detail where a plan can be developed to start practicing. When I email Nick, I'll ask him what are the possibilities of practice rebuilds on sacrificial tubes as a lack of guns shouldn't prevent him from building his skills and confidence.

Does he have enough practice tubes? I'm planning on meeting up with him, hopefully later this year, and could carry along a dud or two if needed.

I don't know that status but I would think that would be fine. The more the better!

I have a dud 21EAP4 (who doesn't :lmao:) with an open filament that I'd be willing to donate if you guys need one, but I have a feeling there's probably more than a few kicking around! Let me know if you want it, I'll be traveling to the Television Museum on Oct 18th

Yeah me too. Paying the price for buying a Holiday with a like new 21EAP4. Even Bob A. couldn't believe I had one with the numbers it showed on my tester and and the picture it had in service. It was an amazing get.

I'm lucky to never have had a dead 21" predicta tube ignoring a necked one in a parts tandem. I did have a dead 17"...of the 8 21" predicta tubes I've had in my hands 2 needed brighteners...one was a customer set, the other was in my GE Forecaster and I recently acquired a rough holiday that had a good 6V tube ...I swapped the brighter tube into the holiday and made it work and be somewhat presentable and sold it....The forecaster looks so much better with a strong CRT now