Mark,
First, set the CAL CUR in the K2 menu to 3.50 - and also make certain
the power supply voltage as displayed on the K2 display is not dropping
significantly during a TUNE. If it drops more than 1 volt suspect your
power supply or the power cable. A low supply voltage can cause the K2
to report HI Cur - the K2 tries to maintain the power requested, and a
lower voltage requires greater current.
Note that at least 2 watts is required to calibrate the KAT2 wattmeter
and to do a TUNE.
The first step in bringing up the KAT2 is to balance (null) the
wattmeter. Adjust the trimmer capacitor for the lowest reading in ATU
menu CALn.
After that, connect a good 50 ohm dummy load and do the CALP setting.
Use an external wattmeter that you trust, or the measurement of the RF
voltage with the RF Probe will work, but requires some calculation in
between adjustments. The external wattmeter is quicker.
With the ATU menu set for CALP, the relays should be set to open all
paths to the capacitors and to short out the inductors, so I doubt that
those relay measurements are of value - unless one of the relays has an
unsoldered pin 1 or pin 10 which will not allow it to switch.
Check the schematic to see which relay pins should be closed and which
should be open.
73,
Don W3FPR
On 9/25/2018 5:35 PM, AE0MM via Elecraft wrote:
Just installed the KAT2 in a newly assembled K2. At power levels greater than
8.0 watts, the K2 was displaying the high current warning. The KAT2 power
calibration was calibrated by measuring voltage with the K2's RF probe at the
feed point to a dummy load.
I removed the KAT2 and remeasured the power across all bands. Again, power was
calculated based on DC voltage from RF probe at dummy load feed point. The
impedance of the feedline and dummy load were retested. (49 to 51 ohms over the
amateur radio bands, measured with a sark-110 calibrated using a set of
reference loads)
Here are the results:
Band Power At Load K2 Current
80 9.7 2.2
40 9.2 2.0
30 9.4 2.1
20 9.7 2.1
17 11 2.1
15 9.3 2.0
12 9.4 2.2
10 9.6 2.3
After remeasuring power, the KAT2 was reinstalled, and its power meter verified
correct at 5 watts. With the KAT2 reinstalled, rechecked K2 current draw at 10
watts on all bands. For each band it measured 20% to 30% higher than without
the KAT2.
With the power level on the K2 set to one watt and the ATU set to CALP, I used
the RF probe to measure a few points on the KAT2 control board, and the input
from the RF board. At the one watt level, there is approximately 1v drop
between K17 pins 2/9 and 4/7.
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