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How to build a frequency standard?


You can't simply build one that is accurate enough to do what you want. How do you know if it is stable enough and on frequency until you check it? What do you check it with if you are wanting to check your counter? Frequency standards are lab quality pieces of equipment. You can however buy a rubidium standard but they are not cheap.

http://www.ebay.ca/sch/i.html?_from...RS0&_nkw=rubidium+frequency+standard&_sacat=0
 
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Captain Kilowatt said:
You can't simply build one that is accurate enough to do what you want. How do you know if it is stable enough and on frequency until you check it? What do you check it with if you are wanting to check your counter? Frequency standards are lab quality pieces of equipment. You can however buy a rubidium standard but they are not cheap.

http://www.ebay.ca/sch/i.html?_from...RS0&_nkw=rubidium+frequency+standard&_sacat=0
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Hmm well it doesn't make much sense to buy a peice of equitment that costs more to check then the peice of equitment you are trying to check. I just heard you buy a 10 dollar crystal and make a frequency standard to make sure your counter is on target. No? gotta buy a 500 dollar standard?
 
805 california said:
Hmm well it doesn't make much sense to buy a peice of equitment that costs more to check then the peice of equitment you are trying to check. I just heard you buy a 10 dollar crystal and make a frequency standard to make sure your counter is on target. No? gotta buy a 500 dollar standard?
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"The next step is to make sure that your test equip. is calibrated correctly. you can have this done somewhere, or you can build a frequency standard for very cheap. the most expensive part is the crystal, and they are like $10. i'll try to draw up a diagram, but for now, do the search thing for "frequency standard" and build any of the circuits you find. this neat little device will put out a singal that is exactly, say, 10mhz.
so you look at you freq. counter and it says, 10.0005. you find the calibration screw inside, and turn it slowly until the counter reads exactly 10.0000mhz. again, they are easy to build. " soo where is the diagram, por fa vor
 
805 california said:
Hmm well it doesn't make much sense to buy a peice of equitment that costs more to check then the peice of equitment you are trying to check. I just heard you buy a 10 dollar crystal and make a frequency standard to make sure your counter is on target. No? gotta buy a 500 dollar standard?
Click to expand...
Paid ~$130 for a used rubidium clock from ebay, and had to build a dual voltage power supply in order to power it. Few of the guys here on this forum have a rubidium unit to keep their counters honest.
 
805 california said:
"The next step is to make sure that your test equip. is calibrated correctly. you can have this done somewhere, or you can build a frequency standard for very cheap. the most expensive part is the crystal, and they are like $10. i'll try to draw up a diagram, but for now, do the search thing for "frequency standard" and build any of the circuits you find. this neat little device will put out a singal that is exactly, say, 10mhz.
so you look at you freq. counter and it says, 10.0005. you find the calibration screw inside, and turn it slowly until the counter reads exactly 10.0000mhz. again, they are easy to build. " soo where is the diagram, por fa vor
Click to expand...


A frequency standard is NOT simply a frequency oscillator operating at a certain frequency. It has t be stable over a wide range of temperature and humidity. It must also be EXACTLY on frequency. My question, again, is how do you know it is on frequency? It is only as accurate as your frequency counter and your counter is only as accurate as the calibration. You cannot just assume your home made oscillator is on frequency because your counter says so if you want it to calibrate your counter. Do you see the catch 22 situation here? A standard is exactly that. A standard that is verifiable. It is a precision piece of gear. Something home made is not going to be that accurate. I have build dozens of oscillators over the years and not one of them could ever be considered a frequency standard
 
805 california said:
10-4 thanks mike
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805 california said:
Google is my first choice and when I don't comprehendo I ask all my friends on worldwidedx. That's what forums are for right?
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1) If you use WWV; that will work. But you need a Ham radio to use to make that happen. ~$500?

2) A TCXO will work; but you will still need something to use as a reference to set it. How do you know that it is right on freq out of the box? ANS: you don't.

Not trying to be a buzzkill; but I am being honest.
I went thru much the same thing you are facing here.
 
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You don't need a frequency standard, but you will need to get your counter calibrated by a certified facility at least once or twice per year (as specified by the counter manufacturer). This certified facility will have its own lab standards properly calibrated to a higher degree of accuracy, and they should provide documentation that is traceable to the National Institute of Standards and Technology (NIST), which used to be called the National Bureau of Standards.

If YOU owned the frequency standard, YOU would have to have it calibrated and adjusted/repaired regularly. That would be much more expensive than having a bench grade (not laboratory grade) counter. But it will still involve periodic calibration. So will all the instruments you use: voltmeters, ammeters, o'scopes, signal generators.... Otherwise, you can't be sure of what you think you have.
 
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Beetle said:
You don't need a frequency standard, but you will need to get your counter calibrated by a certified facility at least once or twice per year (as specified by the counter manufacturer). This certified facility will have its own lab standards properly calibrated to a higher degree of accuracy, and they should provide documentation that is traceable to the National Institute of Standards and Technology (NIST), which used to be called the National Bureau of Standards.

If YOU owned the frequency standard, YOU would have to have it calibrated and adjusted/repaired regularly. That would be much more expensive than having a bench grade (not laboratory grade) counter. But it will still involve periodic calibration. So will all the instruments you use: voltmeters, ammeters, o'scopes, signal generators.... Otherwise, you can't be sure of what you think you have.
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In addition, having /using a rubidium 'clock' is the only other alternative. They are accurate within +/- .1 hz and have a long lifetime (six years - IIRC) and do not require calibration. They are what is used for calibration, since they are very close to being an atomic clock in their own right.

A rubidium clock will take a minute or two to warm up; but when it does it locks on freq and will not drift/let go, just like a pit bull's bite.

Rubidium is a rare earth metal that has characteristics somewhat like cesium, which is used for atomic clocks. Rubidium is also very toxic, so care must be taken when handling these devices.
 
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Beetle said:
If YOU owned the frequency standard, YOU would have to have it calibrated and adjusted/repaired regularly. That would be much more expensive than having a bench grade (not laboratory grade) counter. But it will still involve periodic calibration. So will all the instruments you use: voltmeters, ammeters, o'scopes, signal generators.... Otherwise, you can't be sure of what you think you have.
Click to expand...
In most situations the calibration standard has to be calibrated twice as often as the device you are calibrating. Oscilloscopes in most cases are used just for observation and not for adjusting critical frequency or voltage measurements. For frequency measurements you use the Frequency counters. Voltages use a calibrated DVM or equivalent.
 
I use an old Halcyon electronics off air precision frequency source,
its been checked against two modern gps based standards multiple times & reads identical to 10 digits,

my old Racal 9 digit counter warms up in 20 minutes then cycles up and down 0.3hz from center all day,

i can hook the halcyon to the external input to eliminate the 0.3hz cycling,

you realise there is no such a thing as a stable cb or HF radio & counters drift unless they have a good quality tcxo that is calibrated every so often.

budget counters usually have crappy tcxo's, its better than none but they don't perform like a proper tcxo.
 
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