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RF MEASUREMENTS USING HOMEMADE EQUIPMENT KEN POLLOCK, WB3JOB THOUGH I HAVE
ACCUMULATED MANY DIFFERENT METERS FOR MEASURING RF VOLTAGE, THERE WAS STILL
A GAP IN WHAT I WAS ABLE TO MEASURE.  THANKS TO YEARS OF EXPERIENCE IN
BUILDING SUCH DEVICES, I EASILY FILLED THE GAP BY PUTTING TOGETHER WHAT I
NEEDED.  MY MEASUREMENT NEEDS COULD BE SATISFIED BY PROBES FOR VARIOUS
APPLICATIONS, SUCH AS RF VOLTAGES, FIELD STRENGTH, AND A SIMPLE WAVEMETER.
ADDITIONALLY, A MEASUREMENT HEAD COULD BE CONSTRUCTED TO DISPLAY THE
READINGS.  PROBES I DESIGNED AND CONSTRUCTED FOUR BASIC PROBES A SERIES
DETECTOR PROBE, A SHUNT DETECTOR PROBE, A FIELD STRENGTH PROBE, AND A
WAVEMETER PROBE.  THE ACCOMPANYING SCHEMATICS AND PARTS LIST CAN BE FOUND
AT WWW. ARRL. ORG/ QST IN DEPTH.  THE SHUNT PROBE USES A CAPACITOR IN
SERIES WITH THE PROBE TO BLOCK DC AND RESPOND ONLY TO AC.  THE SERIES
DETECTOR PROBE PASSES DC AND IS USED FOR CALIBRATION.  THE WAVE METER PROBE
COVERS THE LOWER HF BANDS, AND THE FIELD STRENGTH PROBE IS USEFUL FOR HF
AND VHF.  EACH PROBE USES A 1N34A GERMANIUM DIODE.  ONCE THE RF IS
DETECTED, THE SIGNAL IS PASSED THROUGH SERIES RESISTORS TO THE MEASUREMENT
DEVICE.  WHEN A SINE WAVE AC IS DETECTED, A DC VOLTAGE IS PRODUCED THAT IS
1R414 TIMES THE RMS VOLTAGE.  THE SERIES RESISTANCES WILL HAVE A VOLTAGE
DROP EQUAL TO THE PEAK VOLTAGE MINUS THE RMS VOLTAGE.  FOR EXAMPLE, IF 10 V
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