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

[paul swed]

Should have carefully read Corby's comment.
Lamps left.

On Tue, Feb 20, 2018 at 9:40 AM, paul swed <paulswedb at gmail.com> wrote:

> 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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>