A few weeks ago I bought (2) NOS, NIB National NL-6844A nixies from an
ebay seller.
When those arrived they got tested and both work perfectly. -Chuck
---- Original Message ----
From: "Paul Andrews" <[email protected]>
Sent: 12/11/2020 3:19:41 PM
To: "neonixie-l" <[email protected]>
Subject: Re: [neonixie-l] Re: Bad batch of Burroughs 6844A nixies
@Greg. They are all NOS NIB.
@Chuck. I like the domed tube too, but gave up ever trying to find any
that worked. Like you, I am always more impressed with the National Electronics
version of whatever Burroughs produced.
On Friday, December 11, 2020 at 10:14:38 AM UTC-5 Chuck wrote:
@gregebert: 6844A is a non-mercury tube. It has a
relatively short lifespan, and yes, one of its properties is that
during use, the cathode material does get deposited on
the glass. They do silver up quite noticeably over several years of use.
They also get sputtered cathode material on the tiny
ceramic separator washers in the cathode stack which eventually cause
multiple cathodes to glow when only a single cathode is
grounded. After the first ten years of operation in my 6844A clock, I recently
swapped out a tube that started having digits 7 and 8
on together. Moved that to a location in the clock where only digits 0 through
5 are used. - Chuck
---- Original Message ----
From: "gregebert" <[email protected]>
Sent: 12/11/2020 9:47:35 AM
To: "neonixie-l" <[email protected]>
Subject: [neonixie-l] Re: Bad batch of Burroughs 6844A
nixies
Paul - Do any of your failed NOS units have a black or
silvery coating inside the glass ? I'm hoping that is caused by sputtering, and
not simple aging.
On Friday, December 11, 2020 at 6:32:45 AM
UTC-8 Paul Andrews wrote:
I have about 12 6844A, all NOS, none of them
work - they show the same symptoms that you described.
On Friday, December 11, 2020 at
1:45:30 AM UTC-5 gregebert wrote:
I have not been able to figure
that out for years. You would think the internal leads were coated with an
insulator so they dont glow, or perhaps they use a different metal with a
higher workfunction than the actual cathodes, so they would not glow in normal
circumstances. But when the cathodes are still visible, I dont understand why
they have no glow. I doubt they would be selectively plated with another metal,
which completely sputtered away, leaving them unable to glow.
I have a bag of dead
nixies, mostly 5031/6844, took 2 out, and microwaved them for 2 seconds. Got a
brilliant crimson glow. One of them shows some cathodes working, so now I have
to go back thru the bag to make sure I find the totally dead ones, or at least
the ones that have glowing only on the bondwires, and nuke them in the
microwave oven. I have other boxes for dying nixies, and so-so nixies, so I'm
really surprised anything in the "body-bag" of dead ones actually glowed.
Unless perhaps the zap from the microwave oven did something to the internal
metal.
I have some more
experimenting to do.
On Thursday,
December 10, 2020 at 4:57:40 PM UTC-8 Chuck wrote:
Burroughs 6844A is domed not flat. I also have some National Electronics
NL-6844A tubes. Frankly, I have had much better
luck
with the National Electronics brand. This recently purchased batch of (8)
Burroughs 6844A tubes is a bad batch.
The
boxes all are stamped MAR 4 1968. The tubes themselves are date-coded 6750
F20. In white letters stenciled on the glass:
"Burroughs 6844A NIXIE".
The
test I did was that the anode got connected to +170 volts DC through a 15k
resistor. Then the digit cathodes were selectively
grounded to the negative side of that power supply. On all (8) of these
Burroughs tubes, most of what is seen is an intense glow concentrated
around
the tiny internal wires which connect the digit cathodes of the stack, to the
pins. These tiny wires pass closely to the outside of the
Anode
casing which surrounds the digit stack. The glow strikes in the wrong place.
The glow is around the lead wires instead of being
around
the digits. I am very confident from the way these tubes were in those
boxes, that only one of the batch had even ever been out of the box.
So I am
curious what causes the glowing lead wires.
Chuck
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