[time-nuts] PTTI 2012, part 2

Bob Camp lists at rtty.us
Tue Dec 4 15:08:00 UTC 2012


Hi

Vacuum stuff sells by the pound (more or less). The kind you need in this
case isn't the cheap stuff. Pounds go up by the cube of the size. In this
case, I believe you want the fountain portion of the gizmo to be fairly
small.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of paul swed
Sent: Tuesday, December 04, 2012 9:49 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] PTTI 2012, part 2

Basements the key. So for me bigger is better. Heck if its a rack thats ok.
It gets interesting in what types of components you can use if you are
willing to go larger.
Great point on the laser and optics. Funny thing is for small change you
can actually get used optics bench components at least at the last MIT flea
I ran across the items. They were snapped up by the way.
>From what I have seen of time-nuttery and Hydrogen masers I am actually not
all that sure its beyond this group.
Regards
Paul

On Tue, Dec 4, 2012 at 9:34 AM, Bob Camp <lists at rtty.us> wrote:

> Hi
>
> Indeed, you likely won't get USNO grade with a shoe box sized part. You
can
> get one to work and do quite good ADEV. No, I haven't done it, I'm just
> going on what I've been told. The main point being that for a basement
> project - smaller is probably lower cost.
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Poul-Henning Kamp
> Sent: Tuesday, December 04, 2012 9:19 AM
> To: Discussion of precise time and frequency measurement; Bill Dailey
> Subject: Re: [time-nuts] PTTI 2012, part 2
>
> --------
> In message
> <CAMPhiorJihW9z6-q0+Qfd+GPLjs6e8_ovWrDxQoxV=92Hgjo8A at mail.gmail.com>
> , Bill Dailey writes:
>
> >If you look at the papers on portable rubidium fountains
> >they are significantly bigger than a shoebox (65 cm).
>
> Diameter is controlled by dispersion of the launched atoms (=recovery
rate)
> and the layers of shielding.
>
> 65cm looked like close to a minimum for USNO grade, amateurs could
probably
> make do with less shielding.
>
> --
> 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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