Ron,
Yes, the KX3 power output will change with the setting of the WATTMTR
value - that is a calibration setting.
The KX3, like the K3 and K2 before it control the power in a closed loop
system. The power knob presents the requested power to the
microprocessor, and that is compared to the actual power output
indicated by the wattmeter at the output of the transmitter. Drive is
adjusted to make them equal.
The KX3 WATTMTR menu parameter is a calibration parameter. It can be
adjusted to make the power output of the KX3 conform to whatever trusted
power meter you may have available. Before straying too far from the
default value, be certain your external wattmeter is accurate at the
power levels you are working with. Many amateur grade wattmeters are
speced at 20% of the full range value. That means that on a 20 watt
scale, the error can be up to 4 watts - and that applies to any point on
the scale. Those wattmeters with a digital readout (rather than an
analog meter) are usually a percentage of the actual reading rather than
the full scale, but refer to the specifications for your wattmeter for
details.
In other words, at low power levels, be aware of what your wattmeter is
telling you - it may be quite different than the actual indication on
the meter.
73,
Don W3FPR
On 2/25/2014 12:22 AM, Ron wrote:
Has anyone else observed that the Power Output of the KX3 is changed by the
setting of the WATTMTR value?
For example on 20M, CW mode into a dummy load, ATU in bypass. Power set at
10 watts, I measure 6.8 watts with a WATTMTR setting of 1.0. But with a
value of .070, I measure 9.9. The factory sets it at 0.84 I measure 8.2
watts at that value.
At a setting of 12 watts I measure a power out of 8.2 watts at a WATTMTR
setting of 1.00 and 11.5 watts with a WATTMTR value of 0.70.
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