Does cathode poisoning matter?

[celzey11]

In a clock I mean. If it's only the never used cathodes that stop working (like 6-9 on a clock 10's place) but all the other segments work fine in normal use, is it an issue? Or will it start to effect the other segments as well?

[gregebert]

It does matter if you have separate tubes for displaying month, day, and year.

I have a 14 tube clock with IN-18's, with a MM.DD.YYYY HH:MM:SS display format.

Obviously the tube representing 1000 years wont get exercised in my lifetime. I depoison for 1 hr each night with this algorithm

• Units seconds, minutes, and hours are turned off. They are fully cycled during the day
• Tens minutes and tens seconds are cycled 6-9, because all other digits get equally displayed
• All other digits are cycled 0-9

Not all IN-18's are created equal! Some are more susceptible poisoning than others, perhaps a manufacturing difference ?

The tube I have for unit months takes about a week to depoison each month. I chose to keep it in it's slot so I can monitor depoisoning.

[J Forbes]

Just because you aren't using those cathodes, doesn't mean some future nixieist won't want them to work. I'm sure that when these tubes were made, no one was very concerned about what we'd be doing with them in the 2020s. So, we might want to think about what someone will be doing with them in the 2050s, or 2080s, or whenever, and preserve them as best we can.

;)

[Paul Andrews]

I think it is more of an issue that the same cathode is lit for longer. I.e each cathode in the seconds position is lit for only 1/10 of the on time. The 0 or 1 digit in the hours position can be lit for up to 1/2 of the on time, so it will last only 1/5 as long. One failure mode for the tubes is that the cathode disintegrates.

[Dalibor]

This is interesting.. Regarding the cathode disintegration - has anyone here actually experienced a cathode disintegration in a tube containing mercury?

[Paul Andrews]

My source for this was a magazine article that referenced a test made by Burroughs that ran over several years. They held a ‘competition’ to see if anyone could guess how the tube finally failed. This was how the tube failed.

Of course, I can’t find that article now!

On Jul 31, 2020, at 5:42 AM, Dalibor <dal...@farny.cz> wrote:

This is interesting.. Regarding the cathode disintegration - has anyone here actually experienced a cathode disintegration in a tube containing mercury?

On Thursday, 30 July 2020 at 15:44:45 UTC+2 Paul Andrews wrote:

I think it is more of an issue that the same cathode is lit for longer. I.e each cathode in the seconds position is lit for only 1/10 of the on time. The 0 or 1 digit in the hours position can be lit for up to 1/2 of the on time, so it will last only 1/5 as long. One failure mode for the tubes is that the cathode disintegrates.

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[Dekatron42]

The Burroughs Brochure 616 mentions this test but does not contain the description of the cathode disintegration.

/Martin

[gregebert]

If someone has access to an electron microscope, we should go thru our stash of dead nixies to see which ones are candidates for disassembly and inspection. I have one b6091 that got dark and blurry, but still has gas.

[Nicholas Stock]

I have a whole box of dead tubes for such an effort! :)

Sent from my iPhone

On Jul 31, 2020, at 08:09, gregebert <greg...@hotmail.com> wrote:

If someone has access to an electron microscope, we should go thru our stash of dead nixies to see which ones are candidates for disassembly and inspection. I have one b6091 that got dark and blurry, but still has gas.

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[Terry S]

I have access to a brand new SEM... but I doubt my employer would look kindly on me using it for examining nixie tube cathodes! 

We have a whole suite of 3D printers too, able to print almost any material .... alas, I can't use those for personal projects either.

[Mac Doktor]

On Jul 31, 2020, at 2:07 PM, Terry S <tschw...@gmail.com> wrote:

I have access to a brand new SEM... but I doubt my employer would look kindly on me using it for examining nixie tube cathodes! 

We have a whole suite of 3D printers too, able to print almost any material .... alas, I can't use those for personal projects either.

Is this Tantalus Industries?

Terry Bowman, KA4HJH
"The Mac Doctor"

"I don't even gargle Listerine. I heard it kills germs on contact and I don't like the idea of somethin' dyin' in my mouth."—Jim Stafford

[Terry S]

No. Polaris.

[Robert G. Schaffrath]

I have had two cases of cathode poisoning. The first is with Rodan GR-111Pa tubes that are installed on an IN-14 board. I had noticed issues early on and the tubes were a bit dim. It was recommended either here or on the FB Nixie Clock page to replace the anode resistors with a lower value as the GR-111Pa's require a bit more current than IN-14's. I wound up going with 18K and the tubes are now bright. However, the poisoning issue is present on the 3, 5, 6, 8 and 9 digits of the 10's of hours, the 6, 7, 8 and 9 digits of the 10's of minutes and 6, 7, 8 and 9 digits on the 10's of seconds. There is a primitive anti-poisoning routine that runs every minute but it does not do the job as it only cycles once through the digits. As the tubes are soldered in, there isn't much I can do with them unless I were to unsolder and remove them which I am not keen on doing. The poisoning problem is only noticeable when the anti-poisoning routine runs. Otherwise the tubes look fine.

The other case was with ZM1022's installed in a 4 digit Chinese clock. The 10's of hours had issues with the 3 and 8 digits and 10's of seconds had issues with the 8. First thing I did was change the anti-poisoning routine from 10 minute intervals to 1 minute intervals. Then I swapped the tubes around so the problematic tubes got more use in the 1's position. The 10's of hours tube healed up rather quickly and the 3 and 8 digits cleaned up fine. For the 10's of seconds, the 8 is taking a bit longer to heal but it is getting there.The darkened area has shrunk quite a bit with use and only a tiny spot remains that is gradually fading. The tubes that had not suffered from poisoning and are in the 10's positions are still good and I am hoping the more aggressive anti-poisoning routine is helping. It is possible I will have to perform tube rotation every six months or so if I notice the problem returning.

[martin martin]

Have you seen this?

https://www.youtube.com/watch?v=skBwGGQ58MI 

 

~

mcve...@gmail.com

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[Mac Doktor]

On Aug 3, 2020, at 7:51 AM, Terry S <tschw...@gmail.com> wrote:

No. Polaris.

Is that the "vehicle" manufacturer? I was referring to ancient Greek mythology. Or a locked liquor cabinet which is pretty much the same thing.

On Sunday, August 2, 2020 at 1:02:16 PM UTC-5, Terry Bowman wrote:

Is this Tantalus Industries?

Terry Bowman, KA4HJH
"The Mac Doctor”

“And if a message comes from Balaam’s ass, analyze the message, don’t worship an ass.”—Dr. Gene Scott, circa 1985