What are you QRP guys using to measure power?
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N3IZN@...
I have a CB power meter that sort of works on 10 meters. On the 10 watt scale show .25 watts on stock U3 on 28 Mhz. On 40 meters not so good. Shows 2.5 watts.
While on the subject. What about you MF guys, what are you using to measure power? |
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"Facility 406 DM09" <facility_406@...>
Boonton 428D MicroWatt Meter, DoD traceable.
Kurt |
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"Facility 406 DM09" <facility_406@...>
I found a 42BD is that the same?
Yes, sorry, pulled it out into the light, 42BD. Kurt |
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John Molnar <wa3etd@...>
Rough process - if you have a decent scope, take p-p RF voltage, multiply that value by 0.707, square the result and divide by 50...RMS watts...assuming your antenna system is pure resistive 50 ohms!! Get ya in the ballpark - probably as close as CB meter! John WG2XKAOn Tue, Dec 31, 2013 at 6:52 PM, <N3IZN@...> wrote:
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groups@...
Hi All, Very similar to John's method I use an oscilloscope with my U2 terminated in a 50-ohm load. My 'scope will display the amplitude in rms volts which helps with the maths. 73, Peter G4DJB |
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wolfpcgn@...
Hi John, I am using a Perseus SDR with an additional 50dB attenuator. Yesterday I made the first measurement on 10m: 50mW Output (with 3 FETs). Today I startet the first transmissions: more than 3000km (abt.1600 miles) with this power into an ICOM AH8000 (Discone, should work from 100MHz!) Wolfgang (DF1KZ) |
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ke7hr@...
When I do not use a digital oscilloscope and a 50 ohm load, a simple RF probe which works with a multimeter and a 50 ohm load does the trick. N5ESE probe is simple to make and gives pretty good accuracy down to about 30 mW. Look at: http://www.n5ese.com/rfprobe1.htm http://www.n5ese.com/rfprobe2.htm I built a spreadsheet to give me a look up table instead of having to punch numbers into the calculator. The difference that you are seeing between 10 meters and 40 meters may be real. The transmitter is much more efficient at lower frequencies and the RF output goes up. Paul KE7HR |
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Brian Pease <bpease2@...>
You meant peak voltage (not peak-peak). The equation is then correct.
My digital scope gives RMS voltage directly, which I measure across a 50 Ohm dummy load. This works at MF and HF for QRP or higher power. Also at MF I usually use an old HP-400FL AC Voltmeter to measure across the load. This will measure micro-power levels up to 10MHz. These are available at Hamfests for a few dollars. |
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ke7hr@...
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airdry@...
I use this digital wattmeter ... a fine kit ..google k5bcq/Kits .. David VE3KCL |
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ccoles326@...
Hello,
I'm using the radio-kits power meter kit. It's flippin' great! -- It's a really useful kit. Great fun to build. Find them here: https://www.radio-kits.co.uk/ #wattmeter Best regards, Chris M0XFL |
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Eng. Fabio Barroso <fbbrito@...>
Hello, I am using my power meter model RS-102. It is beautiful and accurate with a green backlight. 73, PT7CA Em sex, 29 de mai de 2020 às 17:56, <ccoles326@...> escreveu: Hello, --
Fábio Barroso Brito Engenheiro de Telecomunicações CREA 061787033-0 |
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ajparent1/kb1gmx
I use...
QPSA, a Steve Webber design for over 10 years ago also SWR/frquency counter/aux audio amp. DL5NG terminated diode mount (up to 10mw or so, with calibration table. A dummy load based on caddock resistors (25W) and diode for the 10mw to 20W range HF and calibrated. Bird Model 43 throughline watteter. Large number of slugs for it. Loads: Bird Dummy load (100W), Heath cantenna for higher power. A lower power 100W pint-enna (high power (caddoc) resistor in Pint can. RIgol DSA815T or HP8568B SA with 30DB 50W power attenuator (narda 7768-30) Also a Bird 50W model similar. All in cal. Allison ------------------------------- Please reply on list so we can share. No private email, it goes to a bit bucket due address harvesting |
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Looks like it’s NLA.
Mike WM4B
From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of ccoles326@...
Hello, |
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I think we need a QRP-Labs meter – 0 to 5 watts!
Mike WM4B
From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of ajparent1/KB1GMX
I use... |
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fred.g3srf@...
For low power, I use a Marconi TF1152/A. 1960's vintage it uses a thermocouple so the calibration can be checked at DC and it's good to VHF and low UHF. Two ranges of 10 Watts and 25 Watts. No good for SSB, only CW, AM and FM.
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I use the QRPoMeter by NM0S David Cripe. https://www.ebay.com/itm/QRPoMeter-Digital-15W-QRP-Wattmeter-Dummy-Load-VSWR-Meter-Kit/254596727364?hash=item3b4725c244:g:fgAAAOSwlY1ZMMdT
Handles up to 15 watts, won't let your rig see a high SWR, and is accurate. Easy to build and calibrate. -- Al W4KY |
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Interesting. Mine is off at least 50% compared to measuring with a scope. Build has been validated; something is afoot at the Circle K.
Mike WM4B
From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of Al Clark
I use the QRPoMeter by NM0S David Cripe. https://www.ebay.com/itm/QRPoMeter-Digital-15W-QRP-Wattmeter-Dummy-Load-VSWR-Meter-Kit/254596727364?hash=item3b4725c244:g:fgAAAOSwlY1ZMMdT |
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I'm using the QRP guys 12w dummy load hooked to a resistive voltmeter. V squared divided by 100=watts
-- 73, Dan - W2DLC |
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George Korper
Me too. The QRPoMeter ( I have two) is accurate, fun to build and worth every penny. On Fri, May 29, 2020 at 6:17 PM Al Clark <hotdogx@...> wrote: I use the QRPoMeter by NM0S David Cripe. https://www.ebay.com/itm/QRPoMeter-Digital-15W-QRP-Wattmeter-Dummy-Load-VSWR-Meter-Kit/254596727364?hash=item3b4725c244:g:fgAAAOSwlY1ZMMdT |
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