Determine values of internal KX3 ATU

kx3lc.py

#!/usr/bin/python

# (c) 2016 by Holger Schurig, DH3HS
# this program is released under the GPLv2

import serial, time

# See this post for the backgrounds:
# http://elecraft.365791.n2.nabble.com/KX3-Operating-Tip-Determining-the-ATU-s-L-C-values-and-L-net-configuration-td7560189.html

L_VALUES = (8, 4, 2, 1, 0.5, 0.25, 0.12, 0.06)
C_VALUES = (1360, 680, 330, 164, 82, 39, 18, 10)

debug_cmd = False

ser = serial.Serial(port = '/dev/ttyUSB0',
                    baudrate=38400,
                    bytesize=serial.EIGHTBITS,
                    parity=serial.PARITY_NONE,
                    stopbits=serial.STOPBITS_ONE,
                    timeout=0.1)

def cmd(s):
    cmd = s
    ser.write(cmd.encode())
    ser.write(';')
    r = ser.read(64)
    if debug_cmd:
        if r:
            print "tx '%s;' rx '%s'" % (s, r)
        else:
            print "tx '%s;' " % s
    return r


def sumbits(value, values):
    value = int(value, 16)
    # print "value:", value
    bit = 8
    total = 0.0
    while bit:
        mask = 1 << (bit-1)
        if value & mask:
            total += values[8-bit]
        # print bit, value, mask, value & mask, total
        bit -= 1
    # print total
    return total


def getLCN():
    resp = cmd("AK")
    # print "RESP:", resp
    l = sumbits(resp[2:4], (8, 4, 2, 1, 0.5, 0.25, 0.12, 0.06))
    c = sumbits(resp[4:6], (1360, 680, 330, 164, 82, 39, 18, 10))
    n = int(resp[6:8], 16)
    return (l, c, n)


#############################################################################
#
#  Optional automated radio setup
#

# Just make sure the ATU is on
#cmd("MN023") # select ATU menu
#cmd("MP002") # turn ATU to "Auto"
#cmd("SWH35") # hold CLR to clear all ATU settings for this band
#cmd ("MN255") # turn menu off



#############################################################################
#
#  Determine L and C and how they are combined
#

(l, c, n) = getLCN()
print "L:", l, "mH, ",
print "C:", c, "pF",
if n == 0:
    print "on antenna side"
elif n == 1:
    print "on transmitter side"
else:
    print "invalid answer '%d'" % n