Two ways a bogus contact could be logged:
- Enter in the TX/RX frequency field bubbled to the entry container's
onKeyDown, which calls save() on Enter-in-an-input. Typing a frequency and
pressing Enter tuned the rig AND logged the QSO. The freq fields now
stopPropagation so Enter only tunes.
- WSJT-X/JTDX broadcasts its DX-call field over UDP; when it holds a bare
number ("1"), applyUdpCall dropped it into the callsign, and the next Enter
logged a QSO with callsign "1". Reject any DX call with no letter.