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Calibrating a Dosy

I don't care if the techs Bird has not been calobrated in years , it's no different to me then those funky meters on Cobra/Uniden radios , it's just something to go by. BALLPARK if you will .I thank the good Lord IM not a perfectionist. I just need something to go on and it don't have to be perfect in my cb radio world. Dosy/PDC/Astatic ,simply ballpark meters that will get the job done for the consumer.
 
2M Guy said:
close is as good as you're gonna get anyway.
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Fixating on "exact" wattage measurement is a waste of time. Nobody will hear the difference between a 300 dollar meter reading and an 80 dollar one.
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2M Guy makes a great point. I guess it depends on why you are trying to get an exact measurement.

I have a friend whose dad worked on the radios in Hawaii at the military airbase there. He worked on both the Air Traffic Controllers radios and the ones in the airplanes. When they tuned the transmitters, they used coax looped around fluorescent lights and tuned for maximum brightness. I guess my question would be, do you really -need- an exact number? Or, is what matters most to you maximum brightness? Either way, that peak will be in the exact same place as far as inductor adjustment goes. The light bulb, the rat shack meter, the dosy, and the bird will all show the peak to be in the same spot (Assuming you are using a purely resistive load like you should be.). The folks in the military didn't seem to be too concerned about numbers, should you?

I would only worry about calibration if I needed to provide specific numbers for a specific reason. Bragging rights just isn't enough for me to spend huge coin on a watt meter.

My two cents....

Mopar
 
If you REALLY want to get picky: for some applications and tests, the Navy requires (or used to require) that if you use a Bird and various slugs, they all have to be calibrated TOGETHER, as a system. You can't use a Bird 43 and two different slugs, for example, unless the meter and both the slugs were calibrated in the same lab at the same time.

Makes sense, though. This would truly minimize the error, and the confidence in the result would be increased. I wouldn't want to pay for it, though, unless I was being reimbursed!
 
Beetle said:
If you REALLY want to get picky: for some applications and tests, the Navy requires (or used to require) that if you use a Bird and various slugs, they all have to be calibrated TOGETHER, as a system. You can't use a Bird 43 and two different slugs, for example, unless the meter and both the slugs were calibrated in the same lab at the same time.

Makes sense, though. This would truly minimize the error, and the confidence in the result would be increased. I wouldn't want to pay for it, though, unless I was being reimbursed!
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wow , now thats good to know..my buddy was in the army and said the same thing..as they were working on the radios at the time...and had to be right on, also for the 911 center too!
 
Beetle said:
If you REALLY want to get picky: for some applications and tests, the Navy requires (or used to require) that if you use a Bird and various slugs, they all have to be calibrated TOGETHER, as a system. You can't use a Bird 43 and two different slugs, for example, unless the meter and both the slugs were calibrated in the same lab at the same time.

Makes sense, though. This would truly minimize the error, and the confidence in the result would be increased. I wouldn't want to pay for it, though, unless I was being reimbursed!
Click to expand...

I have read manuals for setting up military grade (URM) equipment and you are correct Beetle, they all had very stringent rules for proper alignment. However, it doesn't seem that those rules were always followed. I would imagine that there were many military techs that weren't issued the proper equipment to do the testing that was specified in the manual.

I guess I was rather unclear. My post would lead you to believe that I think that the light bulb method of testing was the military norm. I realize that isn't the case, and in retrospect I wish I had said that. My point was... Which transmitter will have higher output? The one tuned with the coax wrapped around the light bulb, or the one tuned with the Bird meter calibrated to Navy specs?

The bottom line is that a portion of folks on this forum that have Bird or Coaxial Dynamics equipment are doing it for the prestige of using it. After they have invested their hard earned money, they will fight to the nth degree to convince others that big bucks is the only way. Most folks could get away with cheaper methods. In addition, if you are not using it correctly, you can make a Bird or any other calibrated piece of equipment horribly inaccurate. For example, tuning with a reactive load will render the calibrated equipment just as useless as any other.

I greatly enjoy the nicer equipment that I have invested in, most of which will probably last longer than I do. But, after owning these things, I see now that my money may have been spent more wisely in other ways. That's all.

Mopar
 
The bottom line is that a portion of folks on this forum that have Bird or Coaxial Dynamics equipment are doing it for the prestige of using it. After they have invested their hard earned money, they will fight to the nth degree to convince others that big bucks is the only way. Most folks could get away with cheaper methods. In addition, if you are not using it correctly, you can make a Bird or any other calibrated piece of equipment horribly inaccurate. For example, tuning with a reactive load will render the calibrated equipment just as useless as any other.

I greatly enjoy the nicer equipment that I have invested in, most of which will probably last longer than I do. But, after owning these things, I see now that my money may have been spent more wisely in other ways. That's all.


Thank you very much for your time Mopar (as always) There's no way in hell that I could have ever put it so nicely as you just did. CHEERS !!
 
true that ..i do use my equipment a lot.
meters,ac,dc,scopes,transistor and caps checkers and have 2 freq counters 1 for inline testing and alignments and one for coax hookup.. but through out the years they did pay off..just started doing cb's and ham again and have been picking up a bit..so a good meter will pay off for me.
I do have 2 and there not so bad!
both my meters do read the same which is cool the dosy was redone 1 month ago and matches with this PDC 7000..i had the pdc 7000 for a long time and it is well taken care of so just to match up with the same RMS and PEP reading of a just retuned meter makes me happy..i never pined the needle on this unit to do any damage and when i did move to other places it came with me in a cushioned box...along with my other test equipment! I know this is kind of picky but I value my equipment for me using it, not to show off and say i do have the best...because i don't have the best but between my well kept equipment and all my knowledge i get by and have no problems with customers...same as in the T.v,amp and vcr repair either:)
 
Mopar- no offense intended; just showing the lengths that some agencies (most often Federal) will go to ensure the location of a decimal point :shock: :LOL:

I completely agree that Bird equipment for the average ham or CBer is a large waste of money. I've used Birds (and Coaxial Dynamics-es), but I've never owned either and won't. If I were an installer UNDER CONTRACT to some agency that required such equipment by brand name or by specification, I'd get the equipment and backcharge the agency for the cost, and I'd build the cost of periodic calibration into my bids. ;)
 

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