Ioannis,
The current display on the K2 indicates only the current for the base
K2, not for the K2 and KPA100 combination.
That is why you set the CAL CUR to 3.50 amps even though the KPA100 will
draw much more current.
Yes, the KPA100 does have a scaling on the amount of RF voltage that is
being detected. That is used for power control and has nothing to do
with the current displayed. The result of that voltage is sent to the
VRFDET signal in the K2 (Voltage of the RF Detected).
73,
Don W3FPR
On 4/24/2016 12:05 PM, Ioannis Kassotakis wrote:
Just finished building the KPA-100 for my S/N 2102 K2 (MCU v. 2.03D, KPA
1.06)
The K2/100 does not display the correct 13.8 V power supply current (by
taping Display) when it switches to HI POWER (>10 Watts).
I used a DMM in series to accurately measure the PS supplied current while
checking the K2 display at several power settings . Later, I also measured
the KPA TP1 voltage which is the I sense input to the KPA-100 processor.
For several power settings I got:
PWR (Watts) - PS Current (DMM) Amps - K2 Current Display Amps - KPA/100 TP1
(mV)
RX-0.4 - 0.44 - 0 <x-apple-data-detectors://0>
1.0- 1.72- 1.76 -0
5.0 - 3.3-3.3 - 0
10- 3.8 - 3.8 - 0
15- 4.5 - 1.01 - Not measured
20- 5.4 - 1.02 - 100
40 - 7.0 - 1.20 - 250
60 - 8.5 - 1.28 -380
80 - 9.5 - 1.41 - 500
100 - 10.3 - 1.48 - 580
111 - 10.8 - 1.54 - N/A
The measurements were done at 40 m (7.100) at CW to a dummy load through
KAT-100.
It seems to work fine a LO PWR (<11 Watts) but appears to have a scaling
issue, when the PA switches On to HI PWR mode.
According to the schem (p.61) I Sense is supposed to vary 0-5 V for 0-32 A,
so the TP1 figures seem to be rather low.
Is this a known issue? Is it possible that I have a failed U7 or Q5 ?
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