[time-nuts] Source of Rubidium Lamp for Efratom FRK

[Bob Camp]

Hi

In the (unique) case of the Efratom “light bulb” cell, you can indeed pop them 
out and replace them. Been there / done that with the (then) factory guys involved.
The new bulbs were sold as replacements and did indeed fix the problem of
a dead bulb. About the only added work involved was to re-adjust the frequency
after it had burned in for a few weeks. Repeating that adjustment process as it was
done then would be a bit tough with no Loran :) I still have the Austron, apparently 
it was well enough cared for as a demo in the UK that it’s survived all these years. 

Bob

> On Jul 29, 2015, at 11:49 PM, Chuck Harris <cfharris at erols.com> wrote:
> 
> Hi Mike,
> 
> The Rb lamp voltage is just a guide.  If your Rb isn't working, then it
> is important... If it is, it is just a guide.
> 
> If your bulb is clear, and it is glowing, it is probably also working.
> 
> I seem to recall from HP's descriptions of how their 5065 was made
> that the lamp, and filter cell are a specially matched set.  Just any
> lamp is not necessarily going to work with any filter cell.
> 
> -Chuck Harris
> 
> Mike Niven wrote:
>> Thanks for the comment Bob.  Tracing Efratom through the ages, I see they are now
>> Microsemi.  I wonder whether they will still have a lamp for such a geriatric Rb
>> source and at what price - probably more than the cost of the complete Racal
>> 9475? I will follow it up anyway as I hardly ever see working or scrap FRKs for
>> sale in the UK. --------------------------------------------
>>> On Tue, 28/7/15, Bob Camp wrote:
>>> 
>>> Hi
>>> 
>>> The Efratom bulbs have a “magic mix” of gas in them. The only place I have ever
>>> bought them is direct from Efratom. They were fairly expensive back in the
>>> early 90’s …
>>> 
>>> Bob
>>> 
>>>> On Jul 28, 2015, at 9:56 AM, Mike Niven <mfniven at ymail.com> wrote:
>>>> 
>>>> Would anyone know of a source of the Rubidium bulb fitted in the Efratom FRK
>>>> (and probably other FRx) standards?  I have repaired and refurbished my Racal
>>>> 9475, which is fitted with the older style FRK (not -H or -L) module.  It is
>>>> working properly at present but the lamp voltage is down to 5.5V, which is
>>>> below the stated minimum of 6V.  I have tried rejuvenating the bulb using a
>>>> hot air gun, as described by Corby, but this has had no obvious impact. Hence,
>>>> I have little feel for how much life the existing lamp has left and a spare
>>>> would be good for my peace of mind.
>>>> 
>>>> Many thanks.
>>>> 
>>>> Mike _______________________________________________
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