[time-nuts] Antique Rb Standard - Thanks, Pictures, Parts Request, Question

Magnus Danielson magnus at rubidium.dyndns.org
Sat Apr 28 22:58:13 UTC 2012


Ed,

On 04/29/2012 12:11 AM, Ed Palmer wrote:
> Paul,
>
> On 4/28/2012 1:26 PM, paul swed wrote:
>> Ed
>> Several comments
>> Great pix with the right level of detail to actually see and analyze
>> stuff.
>> Second what a find you have there. A real mans RB nothing small about the
>> gas cells.
>
> Exactly. I can use this as an experimental platform for various changes
> & enhancements. Even an FRK would be awkward to start hacking on.

Indeed. These larger rubidiums is much more fun in that respect.

>> The color of the lamp is way off to my thinking and what I have seen.
>> That
>> color tends to be from a non heated RB. But I need to be very careful
>> with
>> that comment. Perhaps the gas mixtures simply a bit different and so the
>> color would be different. Also its not as bright as I might expect.
>
> Agreed. The color is mostly due to my cheap camera trying to white
> balance something with no white! It's also possible that the color has
> shifted over 40 years due to outgassing, leakage, and absorption of Rb
> into the glass - notice how brown the glass is in the picture of the
> bare lamp. Also, the temperature would be off since the lamp was
> somewhat out in the open. I tend to agree with your assessment of the
> intensity. I'm surprised that after 40 years it's as bright as it is.
> Some years ago Corby mentioned that Tracor lamps usually last for only
> 10 years. Unfortunately, this unit doesn't measure the photocurrent so I
> don't know how much it's faded. I measured the voltage across the
> photocell and got 10 mv across 100 ohms, but that's almost meaningless
> without a working unit to compare it to.

The purple/pink colour is expected. Using Xenon in Rb lamps is common, 
and it has been found that running the lamp in mixed mode, i.e. both 
rubidium and xenon emission, provides a stable and low noise source. 
Xenon can be filtered easily, so the S/N can be kept good in that 
aspect. The hotter Rb only mode of the rubidium lamp provides a higher 
light-intensity pulling and also is a bit more unstable to control the 
light level over time.

So, pink is expected.

>> Noting the various components its quite possible they have drifted in
>> value. Like the transistors thats an age that they would tend to do that
>> over 30-40 years.
>
> I've been watching for that, but haven't seen any problems so far. Even
> the Ta capacitors and Ge transistors are all good. The only component
> change I noticed was the main power supply capacitor.
>
>> Lastly your bench
>> Nothing like a bench jammed with Stuff. Comfortable.
>
> It's possible that the bench has rotted away and the stuff is
> self-supporting. I'm not sure and don't really want to know. :-)

What you don't know doesn't hurt you...

>> Sorry to say I have seen those pins and have no clue how you might find
>> them. Hamfest flea market stuff?
>
> AFAIK, there's no such thing as a hamfest within 500 miles of here.
> Maybe just as well.

I seem to never get informed, but not being a ham helps.

Cheers,
Magnus



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