[Prev][Next][Index][Thread]
Re: Pressure adjustments for smaller tubes
Tom responded to my question about tube pressure for smaller units w/ the
following:
>
> I noticed that the only time I had field problems with tubes I pumped was
>when the sign contained tubes smaller than a foot in the design somewhere. The
>transformers were going bad in these signs and it wasn't until a few of the
>short tubes failed did I realize that the normal fill amount needed to be
>adjusted somehow. Unfortunately for me, this list did not exist and I learned
>most of what I know through trial and error. The fact that there is such a
>short distance between the electrodes is the problem with the normal fill
>pressure. There is not enough material to slow the electrodes down in this
>case and there is a high rate of sputtering at the electrodes. Think of it
>like a bullet proof vest. If you can't make it thick enough then make it out
>of a material that is denser or at least has more resistance.
>
> Anyway, the charts are just a guideline for normal case situations. I like
>Kenny's little program because it figures out mixed loads (merc and neon)
>nicely. I am not sure if he factored in short or longer tube lengths in the
>mix but it certainly is useful for the ability to mix transformer sizes to
>what you have on the shelf. Nice job, Kenny!
Thanks for the feedback & explanations, but I'm still wondering how to
adjust for smaller tubes rather than through trial and error. I do seem to
get a fair number of small units to make & try to connect them if I can to
a larger unit if possible, but sometimes ya gotta do what the man asks
for...
I am curious of how to adjust in a more specific way, though, when I do
have to make them. How much more gas to add? Does this differ any w/ neon
vs. argon mixes? Sorry, but the mathamatics are a bit daunting & esoteric
for me...I think I need it spelled out in the vernacular.
Tom