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Calibrating a Dosy
- Thread starter DCarman
- Start date
"Calibrating a Dosy" seems very much like gold-plating a cowpatty. It's pretty and shiny, but it's still a cowpatty.
lords
Active Member
thats funny...but i don't think that was the answer he needed..Beetle said:
the best thing i can tell you..is find someone with a bird meter
and have them set the dosy using the bird meter same Radio same coax same antenna..
thats what i did!
course its now of just a matter of what to turn on the dosy
Comparing with a Bird might work IF the Bird itself has been recently calibrated. Bird meters are not the be-all and end-all of the RF world, and they need to be calibrated once a year or so just like every other piece of quantitative test equipment out there.
"Calibration" means "comparing", but against a higher standard of KNOWN accuracy. That means certified techicians doing the work in a laboratory, with proper environmental controls, using standards that have themselves been calibrated by a higher echelon laboratory - and all of these calibrations must be traceable to where the buck stops: for the USA, that's the National Institute for Standards and Technology (NIST).
Calibration is necessary, and it isn't cheap.
"Calibration" means "comparing", but against a higher standard of KNOWN accuracy. That means certified techicians doing the work in a laboratory, with proper environmental controls, using standards that have themselves been calibrated by a higher echelon laboratory - and all of these calibrations must be traceable to where the buck stops: for the USA, that's the National Institute for Standards and Technology (NIST).
Calibration is necessary, and it isn't cheap.
you can calibrate any meter with an oscilloscope.
I surprised one of our many techs hasn't suggested it.
I surprised one of our many techs hasn't suggested it.
Again: the 'scope has to be within its calibration cycle for this to be valid.
It could be done, but this just proves that if the only tool you have is a hammer, all problems start to look like nails.
It could be done, but this just proves that if the only tool you have is a hammer, all problems start to look like nails.
lords
Active Member
Again: the 'scope has to be within its calibration cycle for this to be valid.
well if you want to get all tech about it...
calibration cycle is measured by man through math to come out to a set +5% or -5% on any meter through our standards.
and using a meter to calibrate a meter assuming the meter
that your using to calibrate the meter that is off ,is within range,is a fair way to do this..if you know what to turn.
i mean if there were places to do this they would be posted
and we wouldn't be using a meter to calibrate a meter that we assume is off.. its like saying BIRD is the cadillac of meters
well cadillac even gets a recall..after all its all about money
and some peeps can't dish out big bucks for some stuff
this is why they ask for a easier solution!
and seedkey,
you can calibrate any meter with an oscilloscope.
How is this?
well if you want to get all tech about it...
calibration cycle is measured by man through math to come out to a set +5% or -5% on any meter through our standards.
and using a meter to calibrate a meter assuming the meter
that your using to calibrate the meter that is off ,is within range,is a fair way to do this..if you know what to turn.
i mean if there were places to do this they would be posted
and we wouldn't be using a meter to calibrate a meter that we assume is off.. its like saying BIRD is the cadillac of meters
well cadillac even gets a recall..after all its all about money
and some peeps can't dish out big bucks for some stuff
this is why they ask for a easier solution!
and seedkey,
you can calibrate any meter with an oscilloscope.
How is this?
The only one who can determine the calibration requirements for any instrument is the manufacturer. It's his equipment; he made it and he specifies the limits of error for the instrument: ±10%, ±5%, ±1% or whatever. He also specifies how often a particular instrument model has to be calibrated: every year, every 6 months, before each use, or whatever.
Typically, the manufacturing plant has a certified calibration facility right on the premises, and EACH instrument (not just a sample) is individually calibrated and adjusted within the manufacturer's specifications just before it's boxed up. They will retain information on the instruments by serial number but they generally won't provide a calibration certificate unless you specify it when you order an instrument. It's just a piece of paper, but it requires more administrative work, so it'll cost you anywhere from $50-$100 more, in most cases.
I've worked in calibration/metrology for quite a few years. Comparing a Dosy with a Bird and making a few adjustments does NOT constitute a valid calibration unless it's done by the right people under the right conditions, with the right equipment.
Typically, the manufacturing plant has a certified calibration facility right on the premises, and EACH instrument (not just a sample) is individually calibrated and adjusted within the manufacturer's specifications just before it's boxed up. They will retain information on the instruments by serial number but they generally won't provide a calibration certificate unless you specify it when you order an instrument. It's just a piece of paper, but it requires more administrative work, so it'll cost you anywhere from $50-$100 more, in most cases.
I've worked in calibration/metrology for quite a few years. Comparing a Dosy with a Bird and making a few adjustments does NOT constitute a valid calibration unless it's done by the right people under the right conditions, with the right equipment.
And the whole thing in a nut shell is that even when calibrated (correctly), you're just not talking about a 'lab' grade meter to start with. Making a comparison to a meter that you figure is closer to being correct than the one in question is probably 'good enough'. Getting inside and 'tweaking' things is an absolute sure way of 'un-calibrating' anything if you don't know what you're doing. Considering what a 'Dosy' will be used for, close is as good as you're gonna get anyway. It's all relative. And after thinking about my relatives, leave the damn thing alone!
- 'Doc
- 'Doc
there are places you can send your meters for calibrating,
just look at how much this place charges for calibrating none bird meters, then check out the 3% and 1.25% bird slug service charges,
http://www.aspen-electronics.com/services.asp?service=18
just look at how much this place charges for calibrating none bird meters, then check out the 3% and 1.25% bird slug service charges,
http://www.aspen-electronics.com/services.asp?service=18
lords
Active Member
lords
Active Member
2M Guy said:
well when you build and test its a whole different story!
but prices now days your saying pays off well..
well sir it does 100+ watts