Rubidium Oscillators
good members
What are your opinions on the usage of Rubidium Frequency Standards - in the sense - should they be used for short periods of time (until they reach a stable state) as a check only,or is it permissible to run them continuously?
In other words, is the lamp (which is the expensive replacement item), deteriorating on a linear scale, and how fast ? I trust that this isn't a stupid question, as it was put to me recently and I was unsure of the answer.
I currently feed my Racal 9480 T&F Mainframe continuously with the 10 MHz signal from a Ball Efratom Rubidium Standard, assuming that its superior to the OCXO built into the 9480. Or would it be more sensible cost wise, to adjust the OCXO against it on a regular basis?
Like many other such matters, probably the answer is obvious - but what do you say ?
regards
Roy
For maximum stability, the rubidium should be run continuous.
I lost a lamp in a FRK-L last summer. The unit had been running for 9
years continuous - and I was the second owner. It was used at a LORAN
site previous, I am sure they probably ran it continuous, for the same
reasons.
The failure mode is the lamp glass (inside) gets covered with burnt
substance, and loses transparency. Since the unit is looking for less
than a one percent drop in light, for resonance, it does not take much,
to lose lock.
If you do not need high stability, you can run the unit intermittently
as required. After power up / lock most rubidiums are in parts 1x10-9,
and usually in parts 1x10-10 in thirty minutes. If you run
continuously, you should see parts in Xx10-11 to Xx10-12.
Brian KD4FM
Roy Phillips wrote:
good members
What are your opinions on the usage of Rubidium Frequency Standards - in the sense - should they be used for short periods of time (until they reach a stable state) as a check only,or is it permissible to run them continuously?
In other words, is the lamp (which is the expensive replacement item), deteriorating on a linear scale, and how fast ? I trust that this isn't a stupid question, as it was put to me recently and I was unsure of the answer.
I currently feed my Racal 9480 T&F Mainframe continuously with the 10 MHz signal from a Ball Efratom Rubidium Standard, assuming that its superior to the OCXO built into the 9480. Or would it be more sensible cost wise, to adjust the OCXO against it on a regular basis?
Like many other such matters, probably the answer is obvious - but what do you say ?
regards
Roy
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On Mon, Mar 10, 2008 at 10:12:46PM -0500, Brian Kirby wrote:
For maximum stability, the rubidium should be run continuous.
I lost a lamp in a FRK-L last summer. The unit had been running for 9
years continuous - and I was the second owner. It was used at a LORAN
site previous, I am sure they probably ran it continuous, for the same
reasons.
According to various spec docs I have seen, many of the telecom
oriented rubidiums (such as the LPRO and FE series) are designed for
between 15-20 years lamp life continuously on... so running one that way
is not likely to use up available life quickly unless the unit already
has lots and lots and lots of hours on it. And they aren't absurdly
expensive on Ebay these days - bet a new bulb (if even available) is
almost as much as a used but working rb off Ebay.
--
Dave Emery N1PRE/AE, die@dieconsulting.com DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."
I said it wrong, I put 9 years on it, I do not know how long the LORAN
station ran it. So it had more life than 9 years....
David I. Emery wrote:
On Mon, Mar 10, 2008 at 10:12:46PM -0500, Brian Kirby wrote:
For maximum stability, the rubidium should be run continuous.
I lost a lamp in a FRK-L last summer. The unit had been running for 9
years continuous - and I was the second owner. It was used at a LORAN
site previous, I am sure they probably ran it continuous, for the same
reasons.
According to various spec docs I have seen, many of the telecom
oriented rubidiums (such as the LPRO and FE series) are designed for
between 15-20 years lamp life continuously on... so running one that way
is not likely to use up available life quickly unless the unit already
has lots and lots and lots of hours on it. And they aren't absurdly
expensive on Ebay these days - bet a new bulb (if even available) is
almost as much as a used but working rb off Ebay.
A used good bulb usually runs right at $50 on flea bay....
I talked to Efratom years ago when they were running the show in the
middle 80s. A new bulb was $400...
Brian KD4FM
David I. Emery wrote:
According to various spec docs I have seen, many of the telecom oriented rubidiums (such as the LPRO and FE series) are designed for between 15-20 years lamp life continuously on... so running one that way is not likely to use up available life quickly unless the unit already has lots and lots and lots of hours on it. And they aren't absurdly expensive on Ebay these days - bet a new bulb (if even available) is almost as much as a used but working rb off Ebay.