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There are two phenomena going on here.

The reason that there is a radioisotope inserted
into "neon" references, is the neon strikes at
a different voltage when exposed to light, vs dark.

This is an always thing.

The second thing that happens is the neon gas
gets buried into the glass envelop by the
sputtered electrode material trapping it against
the glass envelope. Sputtering changes the
composition, and pressure, of the gas mixture,
which changes the overall characteristics of
the tube.

So, if you have a neon voltage *reference*, it will
always have some radioactive material sintered into
the electrodes to prevent light/dark strike voltage
differences.

If the neon reference has changed its gas composition
too much to strike, for whatever reason, it will have
the wrong voltage reference value too... regardless
of what you do to make it strike.

As to whether adding light of this or that energy
will cause the neon reference to strike over, that
it happens at all is the result of the photoelectric
effect, where stray electrons are created by the
glass envelope, and the electrodes, when the photons
strike. Ultimately, it is the electrons that reduce
the strike-over voltage (see Paschen's law for
more info).

-Chuck Harris

David Wise david_wise@... [hp_agilent_equipment] wrote:
> Would you guys slow down long enough for me to type a reply? :)
>
>
> Tom, Dave,
>
>
> I wish. But the glass stops beta. The Kr-85 worked because it was inside.
>
>
> Bob, Elliott,
>
>
> So many parts in series... sometimes brute force is the best solution, but this
> one puts me off. That's just my personal taste; if you want to do it, knock
> yourself out.
>
>
> Elliott,
>
>
> HP used 1% metal film resistors. The pot is a weak point for long-term stability,
> but I think that since it's in a voltage divider the high-leg tempco compensates
> the low-leg tempco.
>
>
> In a related thread, Alan Melia suggests adding a LED to illuminate the gas tube.
> If the problem was dark effect, brought on by Kr-85 depletion, that should work
> around it just dandy. I hope someone tries it. I can't, my ZZ1000 is still
> working. If I can find a flickering neon at home, I'll try to figure out what
> wavelength LED is the most effective. It will be visible light, not UV, the glass
> blocks UV, same as external nuclear radiation.
>
>
> Dave Wise?
>
>
> ________________________________ From: hp_agilent_equipment@yahoogroups.com
> <hp_agilent_equipment@yahoogroups.com> on behalf of Tom Gardner tggzzz@...
> [hp_agilent_equipment] <hp_agilent_equipment@yahoogroups.com> Sent: Friday, July
> 14, 2017 2:18 PM To: hp_agilent_equipment@yahoogroups.com Subject: Re:
> [hp_agilent_equipment] Re: Replace Neon NE-2 with Zener in 141T PSU?
>
>
>
> Or to a supermarket and find the "LoSalt". Replacing part of the NaCl with KCl
> inevitably includes K40 :)
>
>
>
> On 14/07/17 22:15, Artek Manuals

> manuals@...<mailto:manuals@artekmanuals.com> [hp_agilent_equipment]
> wrote:
>
>
> Go down to one of those 2nd hand store with your geiger counter and find a very
> old $5 watch with the glow in the dark radium painted hands and dial. Peel of the
> minute hand and shrink tube it to the NE-2 :-)
>
>
> Dave manuals@...<mailto:manuals@artekmanuals.com>
>
>
>
> On 7/14/2017 5:06 PM, 'Alan Melia'
> Alan.Melia@...<mailto:Alan.Melia@btinternet.com> [hp_agilent_equipment]
> wrote:
>
>
> ?
>
> The thing is that most "zeners" do not depend on the Zener effect. That only
> occurs around voltages up to around 4volts, above 5v the process is Avalanche
> Breakdown , a bit like a gas tube. Then the temperature coefficient of these two
> processes have opposite senses so if you combine a true Zener with a forward diode
> or an avalanche diode you can minimise the tempco. The lowest tempcos are usually
> around 5 to 6v."zeners".
>
> Alan G3NYK ----- Original Message ----- From: Bob Albert bob91343@...
> [hp_agilent_equipment]bob91343@...%20[hp_agilent_equipment]> To:
> hp_agilent_equipment@yahoogroups.comhp_agilent_equipment@yahoogroups.com>
> Sent: Friday, July 14, 2017 9:16 PM Subject: Re: [hp_agilent_equipment] Re:
> Replace Neon NE-2 with Zener in 141T PSU?
>
> Actually I think the lowest temperature coefficient is around 5V for zener diodes.
> The 6.2 V units are very stable also so you don't need as many of those.
>
> When you put zeners in series you invoke the concern of impedance. Low voltage
> zeners have a fairly high impedance compared to just a few higher voltage ones.
> So if the current through it changes, so will the voltage.
>
> There are more elegant solutions to this 'problem' but the whole thread is
> probably more trouble than it's worth.
>
> Let us know your re sults.
>
> Bob
>
>
> On Friday, July 14, 2017 1:00 PM, "w7qed@...
> [hp_agilent_equipment]"<mailto:w7qed@...[hp_agilent_equipment]>
> <hp_agilent_equipment@yahoogroups.com>hp_agilent_equipment@yahoogroups.com>
> wrote:
>
>
>
>
> Hi Dave,
>
> In theory, ~18x 4.5v zeners would provide the lowest drift reference for a
> pure-zener design.
>
> However, a single 82v zener has a tempo of around 0.073%. Compared to the 0.004%
> of the original reference bulb this is pathetic, however, looking at the dozens of
> carbon resistors, dried out caps, and of course the potentiometer that sets the
> gain (and remember, new pots are generally not better than 100 PPM unless they are
> very expensive), I think the drift and tempo from a single zener will be the least
> of this circuit's problems!
>
> Thanks all for your input!
>
> --E W6EL
>
>
>
>
>
>
>
> -- Dave Manuals@...<mailto:Manuals@ArtekManuals.com>
> <>
>
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