Is it possible to accurately measure RF power (HF/VHF/UHF) with a voltmeter and basic components (diode/cap)? Looking for readings in the 10mW to 5W range. Thanks for the great videos!
I think your SA is also right, you were focussing only on the fundamental, what about the spurs and harmonics power? I would trust the Wavetek power meter given the method it uses to measure the power and it would take into account almost the whole frequency range.
@iowahank 390 is correct. the radio was set to 390 the power meter measured 390. the SA was set to a wide span so didn't have the frequency resolution and displayed 395. If I had lowered the span it would have shown 390 also
Perhaps consider the insertion loss of each test set up, the coax , the 30dB pad etc. See what the difference might be. Might be an interesting exercise. Thanks 😊
I bought one of these years ago and pretty quickly put it at on the bottom of the drawer. I can't remember why. Anyway I thought I'd try again, with my KX3 which I believe accurately reports output power. I found to my surprise that it DOES pretty accurately report the power, probably within 10% but only IF it gives you a stable reading. Once or twice I had to take batteries out to reset it when it went haywire. But I tested it from 2m to 40m, power 3W to 15W. The frequency reading always seemed to be accurate. So I'd say IF you get it to give a stable reading, likely after first turned on, it will be credible even on power. But test it twice.
My HP 8591E is typically +/-.5 dB with respect to my power meter. That said, I’m using a -40dB pad and making measurements well over 100W (50dBm - 55dBm) in the HF bands. My 8591E was last cal'ed about a decade ago. Unfortunately the NIST calibration is more expensive than what I paid for the 8591E. I will have to do some comparison experiments to look at the accuracy between tools. Typically I only use the 8591E SA for relative measurements between signals and trust power meter for absolute measurements.
I've had one of those for a couple of years now and for the price it's not too bad...surprisingly it will sink quite a bit of power but I wouldn't overdo it. Obviously not a bench instrument but at least a relative indicator when you're away from the bench.
The power meter would be the one I'd trust for this, but then, the question would be what you want to measure. The spectrum analyzer just gives you the one peak itself. The power meter will inculde the power in the sidelobes and harmonics.
You are right. A power meter is the only way to get a good measurement. Also a scalar network analyzer is good since it is a sweeping power meter that uses the same sensors.
Hello IMSAIGuy! I am surprised that this instrument is sold (new out of the box) with a 20% error margin on power measurement. Wow... The optimist in me wants to point out that it is pretty bang on in frequency measurement. So at the least, you have a pocket sized frequency counter! It would be great if you could get the actual power measurement more in the +/- 5% area though. I would keep at working on the calibration of the instrument. You might have to "massage" the cal factors that you input into it a bit. I wish I could offer you more, but I have never seen this particular unit before your showing us it today. I do own a small, handheld form factor frequency counter, made by Mcbazel (I think that's the name of it) and it measures RF frequency/power using a rubber duckie antenna (also attached with SMA), which it came with. I am now wondering how accurate the power measurement part of it is... I think that I am going to duplicate your test today over here with this unit. My limitation is that I only have an HP 8591E (50 ohm) spectrum analyser. I do not own a real power meter, so I cannot perform the power measurement with one of those unfortunately. The power meters (on ebay) are still way outside of my reach (price-wise). Thanks a lot for showing your new toy to us today sir! Fred
Hmmmm!!! My experience, if it didn't come with "calibration cert.", beware. All bets are off. And then I have also seen with cal cert. and still not right. So, who do you trust? Interesting "toy". Like your math.
Mind sharing this manual? I'm unable to find it online...Thanks!
Curious how it performs in the higher cellular frequencies....
Is it possible to accurately measure RF power (HF/VHF/UHF) with a voltmeter and basic components (diode/cap)? Looking for readings in the 10mW to 5W range. Thanks for the great videos!
Yes, in fact, I will be releasing a video on that subject in a couple weeks
I'm curious what the black box is that you have attached to your Baofeng?
www.mobilinkd.com/
modification. connect a trimpot 2k in series with R8 1,2k ?
Did you check the batteries? (See FAQ point 1 in manual)
I think your SA is also right, you were focussing only on the fundamental, what about the spurs and harmonics power?
I would trust the Wavetek power meter given the method it uses to measure the power and it would take into account almost the whole frequency range.
Did you try using the 30dB pad when measuring with the GY-561?
No. Why? It would not work. It is a watt meter not a milliwatt meter. It already has a 50 ohm load good to 50W
APRS in the US uses 144.390 MHz, not 144.395.
You are right of course. The radio was set to 390 so the frequency measurement was correct.
@iowahank 390 is correct. the radio was set to 390 the power meter measured 390. the SA was set to a wide span so didn't have the frequency resolution and displayed 395. If I had lowered the span it would have shown 390 also
Perhaps consider the insertion loss of each test set up, the coax , the 30dB pad etc. See what the difference might be. Might be an interesting exercise. Thanks 😊
I've done that in other videos. Usually no more than 0.1dB
@@IMSAIGuy oh well, not much of a difference. :) thanks 😊
Capasidad de frecuencia que registra el dispositivo
I bought one of these years ago and pretty quickly put it at on the bottom of the drawer. I can't remember why. Anyway I thought I'd try again, with my KX3 which I believe accurately reports output power. I found to my surprise that it DOES pretty accurately report the power, probably within 10% but only IF it gives you a stable reading. Once or twice I had to take batteries out to reset it when it went haywire. But I tested it from 2m to 40m, power 3W to 15W. The frequency reading always seemed to be accurate. So I'd say IF you get it to give a stable reading, likely after first turned on, it will be credible even on power. But test it twice.
My HP 8591E is typically +/-.5 dB with respect to my power meter. That said, I’m using a -40dB pad and making measurements well over 100W (50dBm - 55dBm) in the HF bands. My 8591E was last cal'ed about a decade ago. Unfortunately the NIST calibration is more expensive than what I paid for the 8591E. I will have to do some comparison experiments to look at the accuracy between tools. Typically I only use the 8591E SA for relative measurements between signals and trust power meter for absolute measurements.
I've had one of those for a couple of years now and for the price it's not too bad...surprisingly it will sink quite a bit of power but I wouldn't overdo it. Obviously not a bench instrument but at least a relative indicator when you're away from the bench.
Speakingof db, audio in the video was causing my bt speakers to clip.
sounds normal to me
The power meter would be the one I'd trust for this, but then, the question would be what you want to measure. The spectrum analyzer just gives you the one peak itself. The power meter will inculde the power in the sidelobes and harmonics.
You are right. A power meter is the only way to get a good measurement. Also a scalar network analyzer is good since it is a sweeping power meter that uses the same sensors.
Hello IMSAIGuy! I am surprised that this instrument is sold (new out of the box) with a 20% error margin on power measurement. Wow... The optimist in me wants to point out that it is pretty bang on in frequency measurement. So at the least, you have a pocket sized frequency counter! It would be great if you could get the actual power measurement more in the +/- 5% area though. I would keep at working on the calibration of the instrument. You might have to "massage" the cal factors that you input into it a bit. I wish I could offer you more, but I have never seen this particular unit before your showing us it today. I do own a small, handheld form factor frequency counter, made by Mcbazel (I think that's the name of it) and it measures RF frequency/power using a rubber duckie antenna (also attached with SMA), which it came with. I am now wondering how accurate the power measurement part of it is... I think that I am going to duplicate your test today over here with this unit. My limitation is that I only have an HP 8591E (50 ohm) spectrum analyser. I do not own a real power meter, so I cannot perform the power measurement with one of those unfortunately. The power meters (on ebay) are still way outside of my reach (price-wise). Thanks a lot for showing your new toy to us today sir! Fred
Does this device comes with polarity? th-cam.com/video/Wf_SQneBH04/w-d-xo.html
Hmmmm!!! My experience, if it didn't come with "calibration cert.", beware. All bets are off. And then I have also seen with cal cert. and still not right. So, who do you trust? Interesting "toy". Like your math.
my experience .. if you have two meters, you'll spend a lifetime to make them show the same thing.