The SWR meter
Frank, I2DMI, asked about Orion "power fluctuations" on the tentec@contesting.com list. We demonstrate the problem here.
Test conditions:
3.9 MHz CW mode driving 50 ohm dummy load
Adjust Orion power level to show the effect. (Some power levels show much more variation than others.)
Observe Orion's "power" meter and compare with TMC SWR-1K power meter.
The SWR meter
Quicktime Movies (2-4 MB each).
Orion's Display Jitter
(The "problem")
TMC Power Meter
(Barely visible noise plus slow drift. The drift may be in the TMC meter itself.)
Conclusion: The Orion is showing a digital artifact -- the power level sampling, the Dragonball (CPU) update cycle, and the DAC resolution driving the meter. The actual power output is stable within at least a percent.
While this is a measurement artifact and the actual power is stable, it is still a nuisance for the operator and should be corrected in firmware ASAP. Contrast with the Icom IC-7800's exquisite software emulation of an analog d'arsonval meter movement.
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1/2/2005