[neonixie-l] Re: Y1938 blue-coated VFD

['marta_kson' via neonixie-l]

I was telling crap, sorry...

The difference between DT1704 and 1705 is a decimal point. Precence or 
abcence of the mica is indicated by the version letter after the numerals. 

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[neonixie-l] Re: Y1938 blue-coated VFD

['marta_kson' via neonixie-l]

Don't confuse tubes now.

The Y1938 from GE is something quite different than TungSol Digivac DT170?.

The GE tube has the fluorocent areas "printed" on a bigger anode area. The 
Digivac has free segments hanging in the vacuum (1704) or supported by a 
mica (1705).

Both of those comes with many DUD's... Vanishing getter or just weak light. 
The GE tubes are of much higher quality and quite hard to find.

Here is a link to a good picture of an Y1938 without blue painting. They 
exist in both those versions.

http://www.decadecounter.com/vta/articleview.php?item=94

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[neonixie-l] Re: 26 In18 Tubes

['marta_kson' via neonixie-l]

Just use a common plastic hair comb. Use it to charge with static 
electricity and discharge to the glass bulb or the pins. Do it in a dark 
place. The neon will give off little flashes of orange light if it's there. 

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[neonixie-l] Re: Radioactive clock

['marta_kson' via neonixie-l]

philthepill wrote:
>
> Many of the workers who painted the watch hands etc died of radiation 
> poisoning in the early 20th century.  Marie Curie who discovered radium 
> also died of radiation poisoning.
>

Don't scarry up people too much... 
Those poor workers was not informed that ingesting the paint meant goodbye, 
so they wetted the fine brush in thier mouths to have a nice fine point to 
paint with...
Marie Curie did _not_ die from radium, that is a common misconception. She 
volunteered as a nurse during the great war and died from X-ray exposure. 
Good luck with the clocks. Maybe there will be some modern age tritium 
paint available somewhere to touch them up.

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[neonixie-l] Re: IN-8 Digit Failure

['marta_kson' via neonixie-l]

If the pin leading up to the non functional digit beneath the mica sheet is 
glowing then the spot weld connecting the numeral to it's pin is probably 
broken. Maybe knocking on it can restore the connection temporarily, but 
the fault will reappear for sure. There is nothing to do that can correct 
this in a reliable way. Discard the tube and replace. 

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[neonixie-l] Re: Nixie Sputtering at Pulsed Currents vs Constant Current

['marta_kson' via neonixie-l]

The Weston book Cold Cathode Glow Discharge Tubes mentions some tests of 
this. The findings are that sputtering is exponential. At constant current 
increases with current raised to the power of 2.5 and 1.5 at 50% duty if I 
remember correctly. 
As the perceived brightness also drops slower than duty indicates there 
would be a great benefit to use pulsed current. Muxed drive should then be 
an advantage if the peak current is kept down.

Maybe Dalibor could do some testing? That might have been of great interest 
for all of us in this group.

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[neonixie-l] Re: Any info on this display please.

['marta_kson' via neonixie-l]

I agree that thing is most certainly a LED display. Too thin to be a 
panaplex, Try to connect 5V in series with f.ex. 1k8 to various pins and 
look for any light. Those old LED's are very sensitive. Too high current 
and they are instantly gone.

The number 670 may refere to an old red display on prpopto's site. Have You 
any idea of how old Your display might be or where it comes from? It looks 
like a prototype part not in production.

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[neonixie-l] Re: IN-13 Burn-in

['marta_kson' via neonixie-l]

Are You sure You have connected the tube correctly? It's possible to 
reverse the anode and auxilliary cathode and it apperars tp work, but with 
a very high current needed for full scale "deflection". Under those 
conditions, the tube burns out quite fast.

There is a thread about that in this group, titled IN-13 Lifespan

Maybe the link below will work. 

https://groups.google.com/forum/?hl=en#!topic/neonixie-l/PxAF6WguXg4

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[neonixie-l] Re: eBay: Omni-Ray for sale!

['marta_kson' via neonixie-l]

>
>
> Anyone here have more details ? 
>

The german Nixie King have some info on his page: 
http://www.tube-tester.com/sites/nixie/data/SD12W/SD12W-28V.htm

I have a couple of heavily damaged units. They have been exposed to bad 
environment and the film with the pattern that creates the digits are 
mostly destroyed. Otherwise I had bought this one and built a 12h clock 
with three units as one of mine shows the numbers 1..12. Or at least was 
ment to do...

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[neonixie-l] eBay: Omni-Ray for sale!

['marta_kson' via neonixie-l]

Not my auktion.

There is an Omni-Ray display module up for sale on eBay! USD28 BiN. Maybe 
of some interest for someone here.

http://www.ebay.com/itm/NEW-Vintage-Burroughs-Spherical-Display-SD-12-by-Motorola-NOS-/232058166002?hash=item3607be9af2:g:I8QAAOSw6n5XvRdF

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[neonixie-l] Re: Nixie IN-14 Brightness

['marta_kson' via neonixie-l]

The schematic on taht link is CRAP! You will blow some components if You 
try!

It is imperative to have a resistor between the collector of NPN and base 
of the PNP. Otherwise it will end up in a short circuit when the NPN 
conducts. Google around for high end nixie drivers and You will find 
correct schematics.

Use one high end driver for all the tubes if You don't intend to multiplex 
them. Each driver puts load on the HV and is bad. Releases heat and puts 
extra strain on the HV-supply. The total current for 6 tubes and two small 
neon bulbs will be well below the limit for the transistor. Select a 
resistor at least two times what saturates the transistor according to 
worst case on it's data cheet. If left unsaturated it will become quite hot 
and break.

Use a fairly low PWM frequency. Without mux 100Hz is more than enough. Too 
high just makes the driver hot.

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[neonixie-l] Re: removing red coating from tubes

['marta_kson' via neonixie-l]

An easy and dry method is to lift it off with adhesive tape. Just rub on 
standard office tape and when removed the paint will come off with the 
tape. This works on almost all tubes. It's very easy to do.

Some types like f.ex. ZM1210 has been colored with some kind of thin dye 
and for them acetone is the easiest way to remove the red coating. 

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[neonixie-l] Re: Early ZM1000 nixie failure

['marta_kson' via neonixie-l]

Can You see if the mercury giver has released it's content? Did the failed 
tube show any sign of a different color? I have a Telefunken ZM1210 where 
the giver has not melted as it should. That tube lights up in a much more 
reddish color than the OK ones. If there was an overcurrent or too long 
time slot for just that tube of any significance it should have been so 
much brighter that You had noticed something was wrong.

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[neonixie-l] Re: OT: Darkened NOS(?) RCA 6AH6 tubes?

['marta_kson' via neonixie-l]

Great Thanks for all the information! You are all quite right and this was 
something quite new to me.

When I look carefully with a magnifying glass there are definitely lines in 
the coating where the mica wafer has scratched it when the tubes internal 
parts was inserted in the glass envelope. The bottom edge of the coating is 
very sharp and not aligned with the mica. There are no longer any doubt 
what so ever about the coating has been added as an improvement at the 
factory. Knowing the facts those coated ones are the tubes to prefer.

I have now also tested in the receiver with a signal generator and they are 
at least as good as my other 6AH6 without coating.

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[neonixie-l] OT: Darkened NOS(?) RCA 6AH6 tubes?

['marta_kson' via neonixie-l]

As this group has a deep understanding and waste knowledge of hollow state 
devices, I would like to ask for an opinion about the state of those tubes 
pictured in the link below.

They are RCA 6AH6 that appears on the market from several sources, claiming 
they are NOS/NIB. Are there any possibilities the blackening on the inside 
of the glass have been deposited as part of manufacture? On one tube in 
particular there are clear lines visible in the black material, as it has 
been rubbed off by the mica wafer when it was inserted. If so, they was 
clearly dark from the factory.

Nevertheless, it's a foreign matter present inside the tube. Are there any 
reason to belive they are of inferior quality?
Unfortunately I have no tube tester, but listening tests on a receiver with 
those as RF and first mixer gives an impression they offer more noise and 
less amplification. I don't trust my own judgement there, as knowing what 
is in the sockets definitely puts on some bias...

Please give me an opinion and maybe an explanation of the darkening other 
than deposited cathode material. It will be greatly appreciated. Thanks in 
advance for any advices.

  
  

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[neonixie-l] Re: How much voltage do cathode transistors need to be able to handle?

['marta_kson' via neonixie-l]

If You concider blanking the tubes, that includes PWM for intensity 
control, by the cathode drivers then use something that can take the whole 
anode voltage. I.e. MPSA42. Period.



If not You can clamp the voltage to a lower level and use lower rated 
transistors. The clamp must be there, transistors degrade from breakdown 
even if they don't may fail immediately when the current is limited. The 
needed clamp voltage minimum level can sometimes be found in the tubes 
datasheet. Look for "selection voltage". 

The antique 74141/7441/K155ID1 are such devices. The western parts have a 
60-something clamping voltage, the soviet versions about 100V. Those are 
good for any tubes. Unfortunately they are power hungry at about 25mA, 
otherwise they are a good choise. The K155ID1 use to be readily available 
at eBay.

Some tubes have very low selection voltages. I have some recollection of 
ZM1000 to be such a device. 

I also remember having seen some clock built with 40?? CMOS at 15V driving 
nixies directly. The protection diodes to Vdd was used for clamping. That's 
a bad pracice that could possibly damage the devices even if Vdd is safely 
held down by some means to ensure it won't rise.

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[neonixie-l] Re: Sale IN-18

['marta_kson' via neonixie-l]

"There are some oddities like the UDT-3. Every one I've seen has been an 
intentional dud with an internal shorting bar."

Seems very strange to me. I think it's much more likely the metal bar is a 
mistakenly left over detail as the result of a produktion error. It holds 
the pixels in a perfekt row during assembly and when they has been locked 
in positon it's intended to be broken off at the very tiny points that 
connects it to the pixels. Then the bad batch has hit the market instead of 
the shredder...

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[neonixie-l] Re: Linear power supplies for nixies

['marta_kson' via neonixie-l]

Using a double primary as a substitute for a secondary is a big no-no! You 
won't have the appropriate insulation to the mains. You will be just the 
thickness of two layers of enamel from grabbing the mains supply if any 
parts of the circuit can be touched. Scarry, isn't it?...

Compromizing safety to save on money is never an alternative. Order a 
properly made transformer with a safe insulation distance to the mains on 
the HV winding before something lethal happens...

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[neonixie-l] Re: Cathode-poisoning prevention: IN-18

['marta_kson' via neonixie-l]

If You are not going to shuffle around Your tubes, then de-poisoning will 
not help prolong tube life as the heavily used numbers still wear out 
first. If You shuffle them they will have some mechanical stress every time 
that is done and maybe cause a leak. Having moveable tube mounts and switch 
their allocations in software when moved is one solution, but will it 
really be done over time? People are lazy by nature... 

The calendar tubes may benefit from de-poisoning as they shift a little bit 
too infrequent to keep their cathodes fresh. Just step thru the used 
cathodes at some hour when You are likely to be asleep. There are no need 
for fancy drivers, just let the cathodes float when not lit. The never used 
ones are just never used. No need to waste driver outputs on them. This is 
not a rocket science. 

In my opinion the best way to prolong tube life is to use lowest 
recommended current and use PWM to reduce brightness. In the well known 
Weston book he states that tube life is inverse proportional to I^2.5, that 
means a lot of wear for just a little bit more current. He also states that 
the mean current when pulsed (don't remember dutu cycle) just had an impact 
of I^1.5. He had no definite explanation for that, just empirical data from 
sputtering experiments.

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[neonixie-l] Re: Ham radios with Nixies?

['marta_kson' via neonixie-l]

Congratulations to Your licence!

The only factory built trx I'm aware of with a nixie display was the 
Signal/One CX-7.  As I remember the later revisions of it got a LED 
display. The Signal/One was a very advanced radio of it's time, but not 
general coverage so the WARC-bands will be missing. It was all transistor 
except for the final stage. They are very rare as they was quite expensive 
at over USD2000 back in the 70's... If You are lucky to find one for sale 
it will still cost quite a lot as they are quite sought after.

Colins also had some radios with tube displays, but those was VFD's with 
TungSol Digivac's.

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