A CB-channel 22 TX crystal (27225kHz) would result in a frequency of 138.9kHz, just 1.1kHz off the upper band edge and 3.2kHz off the lower band edge.
Given the fact that the two last frequency divisions (see the earlier blog entry) resulting in 4 (two flipflops) it appears somewhat obvious to use just this crystal in a direct conversion SDR receiver.
