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How good are used rubidium standards?

brandon7861

brandon7861

Loose Wire
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Nov 28, 2018
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This morning, I saw a good deal on one, so I ordered it. It is used, of course, but now I am wondering how long those things live? Did I just order something that is near the end of its life, or something that was simply taken out of service and has lots of life left?

What is the best way to operate those? Only when needed, or leave it on all the time? I'm not worried about burning 12-15 watts, just worried about the life expectancy.
 

Rubudium Standards life expectancy is typically 5-10 years. So how long yours lasts depends on its age. Did the seller give you an idea of it's date of manufacture ??

BTW - are you working toward an atomic clock ?? Or . . . ??

- J.J.399
 
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The ad didn't specify the age.

I did send a message about the output, because my understanding is that this model had many options, some with 10MHz out, some with 1Hz out, some with both, and some programmable. Theres a youtube video that says the 10MHz ones have a large sticker, but the description does day 10MHz. If not, I will have to modify it. Found a thread on that too. Anyhow, if they reply, ill ask about the age. My guess, they won't know. Here is the one I ordered.

5-10 years, then I do need to worry. Ill have to use it to set something else and only use it to periodically check that. I am considering either an OCXO or a sealed oscillator at the end of a coax cable 60' down my well casing (above the water) where its always 48°F. My goal is to have something accurate that is never switched off so I don't have to let my counter warm up every time. I know I will need good shielding to leave a 10MHz oscillator running, but I can check for leakage.
 
I guess, the other option is to just run it until it dies and get a newer one later.

Edit: I do like the idea of the clock though. With two of these things, I could do some pretty neat end to end encryption! This was an impulse buy, so anything is possible!
 
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They tend to stabilize in 15 or 20 minutes. Bought one and could never get it to work. Rolled the dice again, and bought another. This one is rock-steady to WWV. You pays your money and you takes your chance.

We power it up only when needed. Haven't made the leap to feeding the 10 MHz output to the ext clock input of our counters and/or signal generators. They tend to stay calibrated for weeks or months between the need for a tweak.

73
 
i bought one of these years ago:

www.ebay.com

10MHz Frequency Standard 10MHz OCXO Reference Board Sine Wave For Radios #TZT | eBay

10MHz Frequency Standard 10MHz OCXO Frequency Reference Board Sine Wave High Stability For Radios. P2: 10MHz sine signal output interface; (10Mhz amplitude: 2.5Vpp) SMA interface. The frequency accuracy of this module output 10MHz signal (+/-200ppb), there is a standard 10MHz sinusoidal signal...
www.ebay.com

I checked it against a known calibrated lab counter we had at work and the damn thing was dead on to .1hz.

Ive been using it since then to check calibration on my counters and i can say that it is still accurate to at least 1hz and none of my counters have needed calibration in the last five years.
LC
 
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Also, Brandon if you're looking for something that you can leave on all the time and is about the most accurate calibration you can get, look into getting a GPSDO.

they can be had for less than 100 dollars on the bay.
LC
 
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I might go that route and just use the rubidium (if it works) for sanity checks.

There's a little test equipment demon inside me that said "you better go with the rubidium in case the GPS satellites get jammed or fail". Stupid, I know, but the idea of it being independent of other people's equipment being functional got the best of me.

5 years is a long time! The cheap counter I have (EZ Digital FC-7105/U 150MHz) seems fairly solid over at least a year, but to get the resolution I want, I have to wait 10 seconds for it to count each time. Not fun when making small oscillator adjustments.

However, I believe if I do get a standard set up, I could just feed that into the external reference in on my SA and use that to check frequencies much quicker than my counter can instead of buying another counter. Not sure if my SA would be ok for that or not.
 
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Here's a little known "secret".

This counter will do 1hz resolution with a 1 second gate time.
www.ebay.com

Hewlett Packard HP 5381A Frequency Counter 80Mhz | eBay

In good working condition, but has scratches, signs of use and surface marks. Hairline crack on screen and missing back foot.
www.ebay.com

it will also do .1hz resolution with a 10 second gate time.

yes it's only 80mhz but for those who only really work on HF stuff it will work just fine.

they are old.
however, there are only two electrolytics in there to replace, and with a fresh calibration you are off to the races!

I have one of these given to me by a friend and i absolutely love it.

just find one with all the LEDs working!
LC
 
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loosecannon said:
Here's a little known "secret".

This counter will do 1hz resolution with a 1 second gate time.
www.ebay.com

Hewlett Packard HP 5381A Frequency Counter 80Mhz | eBay

In good working condition, but has scratches, signs of use and surface marks. Hairline crack on screen and missing back foot.
www.ebay.com

it will also do .1hz resolution with a 10 second gate time.

yes it's only 80mhz but for those who only really work on HF stuff it will work just fine.

they are old.
however, there are only two electrolytics in there to replace, and with a fresh calibration you are off to the races!

I have one of these given to me by a friend and i absolutely love it.

just find one with all the LEDs working!
LC
Click to expand...
With only 7 digits, how does it display 27MHz to 1 Hz resolution? Does it drop off the most significant digit?
 

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