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

[Ed Palmer]

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.

> Good also to see many what I consider to be common components of the late
> 60s and 70s. Also I noticed little or no over heated board components. A
> lot of the lpro type RBs I have fixed are do to over heated components. Not
> in this case it seems.

The power supply board is a little toasty, but otherwise you're right.  
Even the power regulator board, which runs rather warm, hasn't cooked at 
all.

> 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.

> 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. :-)

> 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.

Ed

> Regards
> Paul
>
>
> On Sat, Apr 28, 2012 at 2:43 PM, Ed Palmer<ed_palmer at sasktel.net>  wrote:
>
>> First, I'd like to thank Magnus, Joe, Paul, and Ed for taking the time to
>> provide answers, ideas, and challenges to my assumptions.  It has all been
>> very helpful.  I'm still working on it so I don't have a resolution yet.
>>
>> Second, pictures.  If anyone is interested, check out
>> http://s701.photobucket.com/**albums/ww18/edpalmer42/Tracor%**20304-B/<http://s701.photobucket.com/albums/ww18/edpalmer42/Tracor%20304-B/>.
>>
>> Third, I'd like to build an extender board, but I can't find the
>> connectors.  The contacts are called Varicon and are used both on circuit
>> boards and in connectors.  The connector version is available, but I can't
>> find the board version.  The last picture in the above gallery shows a
>> close-up of the connectors.  They were available in regular and mini
>> versions.  I need the regular ones that stand about 4.3 mm high.  The minis
>> are about 3.5 mm high and won't mate with the regular ones.  New ones could
>> be loose or spaced out on a plastic strip to make installation easier.
>>
>> Fourth, I'm currently working on the cavity tuning.  Does anyone know of a
>> document or research paper that discusses cavity sizes for Rb standards -
>> preferably with equations?  I found this document:
>>
>> http://www.alcatel-lucent.com/**bstj/vol25-1946/articles/**
>> bstj25-3-408.pdf<http://www.alcatel-lucent.com/bstj/vol25-1946/articles/bstj25-3-408.pdf>
>>
>> that talks about cavities in general, but the calculations don't work.
>>   I'm guessing that the Rb cell is changing the resonant frequency of the
>> cavity.
>>
>> Thanks,
>> Ed