Rubidium Frequency Standard Buyers Guide - High Accuracy Clock Project
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- Опубликовано: 16 мар 2020
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In this video I provide some guidance and tips to buying a Rubidium Frequency Standard on eBay.
Some helpful links:
www.ham-radio.com/sbms/LPRO-10...
www.wriley.com/A%20History%20o...
www.tect-electronics.com/uploa...
FEI Frequency Standards:
www.prc68.com/I/FEIFS.shtml
time-nuts.febo.narkive.com/jE...
Mini Precision GPS Reference Clock:
www.leobodnar.com/shop/index.p...
www.ka7oei.com/10_MHz_Rubidium...
FEI Rubidium Atomic Frequency Standards:
freqelec.com/low_g_oscillators/
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Наука
I replaced my Z3801A GPS disciplined oscillator with a Rb standard for several reasons but one of the biggest was simply the heat generated by the power supply and the Z3801A since it was on continuously. Now with the Rb (FE5680A) I can simply turn it on whenever I need it at the bench, wait 2-3 minutes for it to lock and it feeds all the test gear at the bench; done with session off it goes and no more heat. Accuracy is close enough for government work for my ham radio stuff and without being on all the time it should hopefully last longer. Thanks for sharing Martin! (PS - I do have a backup in stock, one is good, two is better!) ;-)
@Frankie Bleddyn For most ham radio stuff, especially at HF and VHF, the Rb standard once it's locked is sufficient. Even at UHF and the microwave bands most folks have found it to be ok. Commercial/government requirements may be different I guess is what you're saying?
I been using a standard to calibrate all my CB radio test gear for years..super solid and economic.
Thank you for this video.
I have an Accubeat Rubidium Unit and it runs off 15V at about 1.5 Amps until it reaches lock, then the current drops to under half an Amp. It seems to work fine. There is however a little sticker covering a calibration adjustment, so at some point it may need re-calibration. Putting it on a scope to compare with my GPSDO, they agree so I trust both devices. I also added an led and resistor from the 15v supply to show me when it reports lock.
FEI also use the Temex (Spectracom/Orolia) LPFRS-01 Rb mudules as well in their GNSS Disciplined oscillators. I stripped down a failed FEI GTF module recently and the LPFRS-01 module inside was still good.
I've recently bought modified Racal-Dana 1998 counters. Modified in the sense that they are equipped with rubidium standards instead of the regular factory TCXO.
Both are Efratom Model FRS-C from week 38 or so in 1995 . They still lock to frequency well within their specification of shorter than or equal to 4 minutes. I took a picture of one and upon looking at that picture just now, I noticed these models are equipped with a lamp monitor out pin. Not that I'm going to take them out just to measure that.
They're still good at the moment and there is, as you said in your video, a DIY revival/refurbish guide available online. You have to be kinda desperate though, as you need to take this wonderful convoluted technical puzzle apart (it's not hard, it seems, but knowing my luck...) and for the lamp rejuvenation itself you have to take that out and blow it with a paint-stripper or something to get it nice and hot (I only read through that part quickly).
Martin, when you setup your GPS disciplined oscillator and the Rb oscillator on two channels of your scope both at 10mHz do you see the phase difference breathe slowly back an forth between the two? On my setup it will be stable for several 10's of minutes then drift slowly apart for a couple of minutes then drift back again usually not more than 1 cycle. Without a second Rb I can't tell what part of the drift is due to the GPS or due to the Rb as well. Guess I should buy a second Rb then I would know. We are talking a difference of one part in 10^10 or so. But I know folks are seeing better than this like between 1 part in 10^11 or 10^12. Could be I am seeing the oven on my GPS oscillator cycling on and off. All very interesting stuff and the most accurate meteorology items I own.
With the proper hardware and a little software you can discipline your Rb standard to the GPS. I have to read up on Allen deviation and how to use the Lady Heather program.
@mjlorton you have not made a solar related video for a really long time.
*I Have a Antelope Audio 10M that needs a NEW Rubidium Oscillator. Can I send it to you for repair?*
Is there any way to buy a NEW lamp and install it?
Glad to see 3458A still have its spot. Been long time since I've seen your videos. Keep up good work.
I have bought five Temex LPFRS Rb modules, all did not work/didn't lock. Replaced all electrolytic capacitors inside - all 5 started to lock and work nicely. So sometimes it's bad power that cause issue, not the actual atomic physics package issues. I've took photos and teardown here: xdevs.com/fix/rb_lpfrs/
P.S. new lab looks much smaller, sadly.
My Rubidium refuses to lock any more. Worked fine for a year of on and off use.
I has a similar problem with several FE -5680 units. The internal firmware kept getting corrupted and had to be re-flashed by the seller. It was a random failure, worked for a while then one day you turned it on and Rb oscillator would not lock on. Ended up replacing it with a Symetricom SA.22C that works great.
Maybe was a cooling failure?
I am looking for GPSDO/ Rb clock for a week o two.
At first I've been looking @ eBay for BG7TBL GPS/GNSS DO and distribution amplifier. Then I read about Rb clock, which has same accuracy as the GPS one, and I'd like to have an atomic clock in my room :) Looking again on the Bay, I found some efratom lpro 101 units, but before I can see this video, I realize that it can be older that me :D I don't want to see my 200 € are burnt in a few month's. Same seller has Datum units for a few euros more...
The accubeat doesn't have the lamp voltage pin :( And specs says 1M4 hours MTBF in optimal conditions (25ºC) but 108k hrs in 60ºC, which is more probably. It is a big drift actually.
Size isn't a big issue, I'm planning to use a HDD case for it.
I'm still in doubt, lpro 101 from datum or accubeat ar-60r?
guys what is this for ?
Hey i want to ask you question not relating to this subject since your knowledgeable guy. I want to block radio frequency radiation coming into my room, im thinking to put aluminium foil on the walls but im not going to ground it, if i dont ground it will there be danger in electric shock from the aluminium since there will be so many? or maybe it will pick up electricity from the electric wires in the wall?
hi have you solved this question ?
@@narimilani2002 Hi, not really but I found a way to block a lot of it which is by putting aluminium screen on the windows. I also bought naturell fabric but I haven't hanged it up yet
@@r.k862 HEY BUT HOW YOU KNOW THE FREQUINCY IS THERE ?
@@narimilani2002 I have a professional radio frequency meter that costs about $500 to measure the readings
@@r.k862 hahaha wow did you compare wher your place is to other places the picup ?
Why buy a rubidium when gpsdos are so cheap these days? What are the advantages to a rubidium over a gpsdo? I can't think of any apart from there is a big chance of the GPS satellites going down at some point
The way I look at it -- the GPS has great long term accuracy but poor short term stability the Rb had great short term stability but its Accuracy is unknown unless calibrated against something. Thus use the Rb for your local bench testing but calibrate it over a long time period with the GPS. It's very cool to put the Rb and the GPS signals (10mhz ) on two scope channels triggering on the Rb channel and watch the two wander past each other at a rapid rate until things warm up. Then all of a sudden the Rb locks on and the two signals snap into lock step just slightly wandering back and forth less than one cycle over 20 or 30 minutes.
For a nice view you do need to condition the raw GPS 10hnz with a frequency locked crystal oscillator because there is a lot of phase jitter in the GPS output due to the DSS frequency synthesizer in the receiver.
Depending on the loop filters in your GPS disciplined oscillator it may take many minutes to several hours to have the oven crystal oscillator locked on to the average GPS frequency. The Rb standard will take about 4 minutes to lock on. You can also get drop out on the GPS signal. Good disciplined oscillators will spec this as hold over time and give the maximum drift based on outage.
@@craigs5212 Thanks very interesting, I've long suspected the op from the GPSDO has jitter on it, if you compare it on a scope with the 10 MHz reference of my hp counter with a very high quality OCXO in it then the short term frequency variations are visible but its good enough for me.
On that subject I installed the OCXO in the counter and calibrated against the GPSDO over a year ago it still read only a couple of mHz drift over that time period, despite being power cycled a few time due to power cuts!
On the same subject years ago before I bought a GPSDO, I built a 10 MHz reference phase locked to the received signal from the BBC transmitter on 198 kHz which has a very accurate frequency reference, I think using a cesium beam source. As I am close to the transmitter I'm receiving by ground wave so path variations don't upset the received signal, anyway comparing the op from this with a GPSDO, there is definitely a very slow phase change between the two signals which calculates to a frequency error between the two of around 70 uHZ!
anyway fascinating stuff
Helpful video
$20k of test equipment on a $5 sagging shelf.
There's more rubidium on Earth than copper, fun fact! But there's less caesium than copper.
Looks like it came out of an old Israeli nuke from the 80's
Leading ad is a huge turnoff. Are you that strapped for cash
joe72205 than do not watch...🙄