[time-nuts] The "NAKED" 5065A optical unit

paul swed paulswedb at gmail.com
Tue Feb 20 14:40:49 UTC 2018


Wow on the right, is that the lamp?
Thats one large lamp to light. I am use to the little capsules about the
size of a pr-1 light bulb.
This is a keeper picture.
Regards
Paul
WB8TSL

On Tue, Feb 20, 2018 at 8:24 AM, Bob kb8tq <kb8tq at n1k.org> wrote:

> Hi
>
> Indeed very cool pictures.
>
> If the lamp is like most gas bulb lights, there is indeed a “strike
> voltage” required
> to get things going (or an RF excitation). There inevitably is some
> temperature
> dependence as well. A constant current driver might be the better bet.
>
> Bob
>
> > On Feb 20, 2018, at 4:30 AM, Poul-Henning Kamp <phk at phk.freebsd.dk>
> wrote:
> >
> > --------
> > In message <AABPJY7PFAJKDQYS at smtpout01.dca.untd.com>, cdelect at juno.com
> writes:
> >
> >> Here is a PIX of the optical unit from a 5065A totally removed from the
> >> shield assembly.
> >
> > Nice!
> >
> >> Left to right:
> >>
> >> Lamp assy
> >> lamp oven cylinder
> >> lamp reflector/convection block/diffuser
> >> Rb85 filter cell
> >
> > It looks like there is a square filter of some kind
> > between the reflector and the filter cell ?
> >
> > I've been thinking a little bit more about power for the lamp assembly.
> >
> > Since I have the lamp on the bench-supply I am going to plot lamp
> > voltage vs. photo-I because it looks like a threshold rather than
> > a linear relationship.
> >
> > If that is the case, I think it will make sense to give the lamp
> > its own adjustable voltage regulator (LM317), so the power can be
> > reduced to what is optimal/necessary without having to take the
> > lamp apart and change a resistor.
> >
> > A 1R resistor between the 22-30V supply and the LM317 will make it
> > easy to monitor lamp current, and a 300mA short-circuit protection
> > is a nice bonus.
> >
> > If need be, the regulator could start out at 20V and drop to something
> > lower in a matter of minutes.
> >
> > Actually, now that I think about it, I should try to measure if it
> > is gives better stability if I drive the lamp with constant current,
> > constant power, constant voltage or constant photo-I...
> >
> > --
> > Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> > phk at FreeBSD.ORG         | TCP/IP since RFC 956
> > FreeBSD committer       | BSD since 4.3-tahoe
> > Never attribute to malice what can adequately be explained by
> incompetence.
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