hi Telamon:

A more complex reason for the RX340 non-lock is that the radio has a
front-end analog RF AGC followed by a DSP AGC. The locking problem could
be related to the way the two loops interact in various reception
situations.

the RX340's 16-bit ADC is not ideal as this limits AGC inside the DSP. the
"software" AGC must keep altering [via DAC] the analog gain during fades.
new ham gear uses 24-bit ADCs.

regards,
phil