Elecraft KXAT1 - Manual (Page 11)

11
Troubleshooting
If the ATU menu parameter shows "- - - " at all times, look for a connector shifted by one position, an
unsoldered pin, U1 installed backwards on the ATU board, or a defective U1. Also check the ATU PC
board for shorts to ground, solder bridges, and unsoldered
If the ATU menu parameter becomes "- - - " after doing a tune-up, it may be due to very high RF
feedback into the transceiver. Turn power off and back on, then re-test the ATU using a dummy load or a
different antenna. If it functions correctly on a dummy load but not on your antenna, try using a balun.
If the SWR isn’t < r 1 . 2 with a 50-ohm load, C9's setting may be incorrect.
If the power indicated is always about 0 watts, the windings of T1 may be reversed, or one or more leads
of T1 or L1-L4 may not be properly stripped.
If the ATU shows an error message (E x x in the menu where x x is between 1 and 49), you may have a
defective microcontroller (KXAT1-U1). E x x numbers 50-99 are used for tune-up algorithm tracking, and
do not indicate a problem.
If SWR is not displayed after exiting TUNE, you may have high RF feedback into the transceiver. You
may need to improve your ground system, move the antenna farther away, or use a balun.
If the tuner is unable to achieve a low SWR on some bands, even with several different antennas, you
could have a single defective relay or component on the L-C board. Start by slowly scrolling through ATU
menu parameters L 0 through L 3 , C 0 through C 3 , N 1 , and N 2 . These are intended for relay testing. For
example, L 0 turns off all of the inductor relays (K4-K6). L 1 turns on K4, etc. Similarly, C 0 turns off all
of the capacitor relays, and C 1 turns on K1. N 1 and N 2 place the network configuration relay, K7, into its
two positions: CTX (C-in L-network) or CANT (C-out L-network).
If the relays are all working but you suspect an inductor or capacitor, you can test each L and C by
noting their effect on SWR, one at a time. Start on the highest band. Connect a 50-ohm dummy load to one
of the antenna jacks, select L 0 , do TUNE, and note the SWR reading. Then select L 1 and do TUNE again;
the SWR should change by a small amount. L 2 should have a larger effect, etc. If the inductance selections
cause the SWR to go off the scale (9 . 9 ), switch to a lower band, go back to L 0 , then test the remaining
inductors. Similarly, you can test all three capacitors, starting on the highest band with C 0 , C 1 , etc. You'll
know you have found the bad component if it has too large or small an effect (or no effect) on SWR, in
relation to the others tested.