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After reading several posts expressing concern about low K3 RF power output, I decided to run some tests on my own K3.
Equipment used: K3/100 #0224 (2.7khz stock filter) with current MCU and DSP firmware (1.78 / 1.58); Telepost LP-100 digital vector wattmeter; Telepost LP-200 dummy load wattmeter; MFJ-872 peak/average wattmeter; Daiwa CN620B wattmeter (average reading); Elecraft 2T-gen; high quality non-reactive RF dummy load. No antennas. K3 ATU bypassed.
The K3 was set to request 100 watts output on 14.250 Mhz USB. The 2T-gen was connected to the front mic input and mic gain adjusted to a value of 20. This resulted in 5 bars of ALC. Compression was set to an arbitrary (and low) value of 10.
Results, LP-100 wattmeter: peak power measured 97.6 watts (averaged over 5 measurements). Set to measure average power, the LP-100 repeatedly measured about 60 watts output.
Results, LP-200 dummy load wattmeter: 99-100 peak watts reported over 5 measurments.
Results, MFJ-872 Peak/Average wattmeter: 'Peak' reading on analog scale - 85 watts. 'Average' reading on analog scale - 55 watts.
Results, Daiwa CN620B average-reading wattmeter: 40 watts per analog scale.
While the LP-100 and 200 were in close agreement, keep in mind that I calibrated them myself against a nominal 25 RF peak watts as determined by an accurate oscilloscope. The other two instruments reported somewhat disparate power values compared to the LP-100/200 and one another. I'm not drawing any definite conclusions from these results; I'm simply reporting them out in the event some readers might find them helpful or interesting.
73,
Bill, WA4KBD
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