Thanks Don, That means that at HI PWR (>11 Watts) should disregard the displayed PS current figures. I thought that KPA100 processor would communicate the I Sense back to the MCU and display the correct current figure after rescaling. I understand that is not the case.
73, Ioannis PA1EQP On Sunday, 24 April 2016, Don Wilhelm <[email protected]> wrote: > 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 ? >> >> >> > -- Ioannis Kassotakis ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
