TOTAL-IMD MEASUREMENT:
Equipment List:
- Double-filter radio such as a TS-830S, FT-1000, TS-930S, TS-940S, et
cetera (used as the test receiver).
- 1db increment, 50-ohm, step-attenuator that covers 0 - 70db. (H-P
355A/B, et cetera)
- Male coax connector with a roughly 15cm wire probe soldered to center
conductor.
Test Procedure:
- Connect the radio/amplifier under evaluation to the antenna.
- Connect the probe to the input of the step-attenuator.
- Connect the output of the step-attenuator to the test receiver.
- Tune the test receiver to the transmit frequency of the radio/amplifier
under evaluation.
- Say 'ahhhhh', or whatever, into the microphone of the radio/amplifier
under evaluation.
- Adjust the step attenuator for a reading of S9 on the test receiver.
Record reading.
- Tune the test receiver 3.6KHz above the transmit frequency for
measuring LSB IMD, or tune 3.6KHz below the transmit frequency for
measuring USB IMD.
- Sah 'ahhh' and adjust the step-attenuator for a reading of S9. Record
reading.
Total-IMD is the difference between the two readings.
Rich---
R. L. Measures, 805-386-3734, AG6K
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