This may be a long shot, but I'd like to verify and calibrate my old Leader frequency counter and I'm looking to see if anyone might know of a frequency standard in the Chicago area that I could possibly rent or at least maybe use to just verify the accuracy of the unit. It's never been too big of a deal, but I just picked up a Sound Technology 1700b, and in calibrating it, it looks like either it or my counter might be off just a little. I bought the counter used, so I'd be curious as to where it's sitting. I just can't justify buying a standard right now, and paying for a cal wouldn't be worth it for this unit. Any suggestions would be much appreciated. Thanks!
In the good old days, one the best easily available standards was the locked chroma sub carrier oscillator in a TV. The accuracy was superb, 443361875 Hz -/+ 1Hz for PAL. Sadly long gone now.
Do we have anything similar like that available now I wonder. There is the 19Khz FM stereo subcarrier regenerated to 38Khz in the receiver. I don't know the accuracy of that though, and you would need to extract it.
Maybe someone can come up with something similar.
For low frequencies an audio test CD is workable up to 20Khz. If you suspect a major error in the counter then it would show.
You can also use any running quartz crystal osc in such a player as well. Its not to lab standard accuracy but its pretty good as a check. Don't confuse quartz oscillators with ceramic resonators as those are nowhere near stable or accurate enough.
Do we have anything similar like that available now I wonder. There is the 19Khz FM stereo subcarrier regenerated to 38Khz in the receiver. I don't know the accuracy of that though, and you would need to extract it.
Maybe someone can come up with something similar.
For low frequencies an audio test CD is workable up to 20Khz. If you suspect a major error in the counter then it would show.
You can also use any running quartz crystal osc in such a player as well. Its not to lab standard accuracy but its pretty good as a check. Don't confuse quartz oscillators with ceramic resonators as those are nowhere near stable or accurate enough.
All you need is a radio that can pick up WWV and an oscillator that will put a harmonic that matches.
Typical is a 100 kHz oscillator with a trim cap. You tune to WWV and turn on the oscillator. You will hear a difference tone. Adjust the oscillator until it becomes a beat frequency of say 3 seconds. Now if you use the 10 MHz station and beat to 1 cycle then your oscillator will be 100 KHz plus or .01 Hz.
Often you don't need an external iscillator you can just adjust the reference oscillator in the frequency counter.
You can buy a shortwave radio for as little as $20!
Typical is a 100 kHz oscillator with a trim cap. You tune to WWV and turn on the oscillator. You will hear a difference tone. Adjust the oscillator until it becomes a beat frequency of say 3 seconds. Now if you use the 10 MHz station and beat to 1 cycle then your oscillator will be 100 KHz plus or .01 Hz.
Often you don't need an external iscillator you can just adjust the reference oscillator in the frequency counter.
You can buy a shortwave radio for as little as $20!
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Get on the "time-nuts" mailing list: Time-Nuts -- Precise Time and Frequency for Amateurs
Almost any ham radio club out there is going to have someone willing to help you. There are hundreds of folks who participate in their annual (November) frequency measuring contest.
Almost any ham radio club out there is going to have someone willing to help you. There are hundreds of folks who participate in their annual (November) frequency measuring contest.
Simon beat me to it, our tax dollars provide us with WWV, which is SUPER accurate. Used to be NBS - National Bureau of Standards, now they call the agency NIST - National Institute of Standards and Technology.
Aside from the RF parts, the audio was, and I assume still is, alternating 400Hz and 1000Hz tones, take your pick. Even the clicks marking seconds are exact number of cycles of the two frequencies.
Aside from the RF parts, the audio was, and I assume still is, alternating 400Hz and 1000Hz tones, take your pick. Even the clicks marking seconds are exact number of cycles of the two frequencies.
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