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Recommend a Wattmeter
- Thread starter Rok55
- Start date
Gotta watch that peak power claim. I have the Diamond SX-1000 (great meter) however the peak claim is stretching it. All the switch does is switch a capacitor into the sampling circuit to make the meter read CLOSER to peak power but it is still not true peak power. IIRC even the manual states that it will only read about 70-80% of true peak power. Basically if the peak function works without any source of power then it is NOT a true peak reading meter. This applies regardless of the manufacturer.
This is the "passive" peak-reading circuit. Requires no battery or power supply, but falls short in accuracy. The capacitor that gets switched into the circuit gets charged up by the voice peaks, and discharges back into the meter's coil during the "valleys" between those peaks. Holds the pointer up, but still allows it to fall slightly while it waits for the next peak to charge it back up.
You will usually find that the peak-reading accuracy is best on the highest power scales. Most such meters will switch wattage ranges by putting a higher resistance in line with the meter movement on higher power scales. The higher this resistance, the longer it takes to discharge the peak-holding capacitor, and the better it holds the meter's pointer up between voice peaks.
The ever-present Dosy meters will exhibit this habit.
73
You will usually find that the peak-reading accuracy is best on the highest power scales. Most such meters will switch wattage ranges by putting a higher resistance in line with the meter movement on higher power scales. The higher this resistance, the longer it takes to discharge the peak-holding capacitor, and the better it holds the meter's pointer up between voice peaks.
The ever-present Dosy meters will exhibit this habit.
73
I see a few variants of the Daiwa, some are square shaped some are rectangular.
Is the Daiwa a true pep meter? I ask because the 12v input is marked for the light only.
YES it does read true peak power. I have a couple of them.
Professional Series Bench Meter
Average and True PEP Reading Meter
Frequency: 1.8-200MHz
Power Range Forward: 20/200/2kW
Accuracy: �10% (at full scale)
SWR Detection Sensitivity: 5W min
Input/Output Impedence: 50 OHM
Input/Output Connectors: SO-239
Dimensions & Weight: 6.25" x 4.3" x 4.8" / 2lbs. 3ozs.
Lighted
Average and True PEP Reading Meter
Frequency: 1.8-200MHz
Power Range Forward: 20/200/2kW
Accuracy: �10% (at full scale)
SWR Detection Sensitivity: 5W min
Input/Output Impedence: 50 OHM
Input/Output Connectors: SO-239
Dimensions & Weight: 6.25" x 4.3" x 4.8" / 2lbs. 3ozs.
Lighted
So why does it state LIGHT for the 12v input, seems like a bit of scam advertizing.
Ok dumb question, so I would need to put at least 5 watts into the meter for it to read my swr? That's fine with a radio with variable power but a couple of my radios only deadkey about 3 watts. I guess I could always key a tone into the microphone and check my swrs with about 10 watts.?
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The manual actually labels that input as "DC power socket for meter and p.e.p. function"
The CN-901 is simply a newer version of the CN-801 but basically identical.
http://www.cometantenna.com/wp-content/uploads/2013/09/CN-801_series_manual.pdf
I'm going to go against the grain here .
I've done this professionally and have the gear but for years I didn't need the high price spread.
You see my "elmer" was a broadcast engineer. I had access to Bird, Harris, Simpson, HP-Agilent, Singer...
I found the biggest damn meter I could for the lowest price and gave it two knobs . FWD/REV and 2-20-200-2000 W .
I calibrated it against a bird 43 with the proper slugs in it .
I built several variations of this basic circuit and continued to refer back to the original for calibration. The non portable large face (10" across, Yeah nearly Warner Bro's ) at 2W full scale was great for small signal work. At 20 it was fine for most all SSB radios.
The portables were a collection of rugged cases if not meters. I did this for almost 20 years before Having to finally buy the high priced spread.
You can buy a lot of hot dogs for what you spend on a Dosey/Diawa/Bird/WTFever. If you're not a pro, build it and find a pro that will allow you to put it in the same line with his bird. Folks, a bidirectional relative power meter is the second easiest project you will ever build. You will keep it the longest and use it the most and have to look at it every day. Do it right and make it look good .
You will not regret it .
I've done this professionally and have the gear but for years I didn't need the high price spread.
You see my "elmer" was a broadcast engineer. I had access to Bird, Harris, Simpson, HP-Agilent, Singer...
I found the biggest damn meter I could for the lowest price and gave it two knobs . FWD/REV and 2-20-200-2000 W .
I calibrated it against a bird 43 with the proper slugs in it .
I built several variations of this basic circuit and continued to refer back to the original for calibration. The non portable large face (10" across, Yeah nearly Warner Bro's ) at 2W full scale was great for small signal work. At 20 it was fine for most all SSB radios.
The portables were a collection of rugged cases if not meters. I did this for almost 20 years before Having to finally buy the high priced spread.
You can buy a lot of hot dogs for what you spend on a Dosey/Diawa/Bird/WTFever. If you're not a pro, build it and find a pro that will allow you to put it in the same line with his bird. Folks, a bidirectional relative power meter is the second easiest project you will ever build. You will keep it the longest and use it the most and have to look at it every day. Do it right and make it look good .
You will not regret it .
Kopcicle, you were fortunate.
Unfortunately, I have no "Elmer". While the project that you mention sounds like a lot of fun, I would have to buy a good meter to calibrate against, and then I wouldn't need to make the meter.
Unfortunately, I have no "Elmer". While the project that you mention sounds like a lot of fun, I would have to buy a good meter to calibrate against, and then I wouldn't need to make the meter.