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Re: NEON- RE: small tube lifetime
Marcus Thielen wrote:
>
> Dear Tom W. or anybody else:
>
> Do you know a physical reason why short tubes should have shorter life?
> Temperature - NO. When properly processed, no outgassing will occur, thus
> bombarding temperature is always much higher than operating temp.
>
> Gas volume - you have to pre-compensate to have the optimal equilibrium
> discharge pressure - no more occlusion in the 'trode body when equilibirum
> is reached.
>
> So please tell me a GOOD reason why small tubes should have shorter life
> - I don't know any. My 6mm ones, 20cm long ore operating now for more than
> 2.5 years on 25mA (red) without any sign of ageing.
>
> Marcus
Add from dirk:
Dear Tom W,
For over 6 moth ago I produced two times a backfilling chart related
to the tube diameter and the length of the tube.
If you don't have them you can find them at Kennies:
http://www.neonshop.com
I think I called them backfilling tables, but I am not sure about
that, maybe somebody can jump in to you.
Looking to the chart I produced, you can see that there is no difference
in the amount of rare gass (the volume) when 1 unit is filled with a
length of 1 foot or a unit with the same diameter with a length of 4
feet.
Be aware of the fact that when you use my chart there is a possibillity
that your transformer chart cannot be accurate any longer. As the
smaller units
have now a higher Ri (internal resistance) you can install less footage
to a transformer as the chart is telling you. Nothing to worry about,
but think about it, so recalibrate each section with a true RMS
current meter.
I will make one more comment and that is that we always use here in
Europe for "smaller" diameter tubing "smaller" (like 10 or 13/15 or 18
mA)
transformers and I must say that that is much more "elegant" then the
uniform use of a 30 mA big one. The light output is them not so bruatl
but the way it should be, nice, decent, soft and elegant with the tube
lighted up all over the wall and not only that too hard internal
discharge
line. Can you tell me if you can buy these 10, 13/15 or 18 mA
ransformers in
your country.
As Marcus wrote in the above, shorter tube have a lifetime as long as
longer
tubes, BUT when you install transformer section the "short" tubes have
to be
of equal length, then everything is okay. (so good Tom?). Another story
is
when you have to install short and long tubes on one transformer. Then
you
MUST use my backfilling chart to make sure that ech tube have the same
electrical length and for that reason the shorties have more rare gas
(that is higher backfilling pressure) in it. Doing this the electrical
resistance of a 1 foot unit is as high as a 3 feet unit and therefore
you can
install less tubing to a transformer.
Hope this helps.
Best from dirk a. boonstra
References: