Merry Christmas Jim,
For added COMSEC, I strongly advise those with transceivers to leave the microphones unplugged. This is a sure way to limit giveaway radio frequency (RF) emissions.
For those who have to make transmissions, for example contacting family members, the use of [highly directional] high gain multi-element “beam” (yagi) or log periodic yagi antennas at the base station would reduce the RF signature. The higher the gain a “beam” antenna has the more elements there are on the boom and therefore the narrower the signal spread will be, in degrees, off the front of the antenna. An antenna that has 11-15 elements versus one that is constructed with 4 [elements] has a tighter pattern both vertically and horizontally. This, therefore, reduces the probability of intercept of the signal. [With highly directional antennas,] interception is not eliminated but the more line of sight the signal is, the harder it is to locate. This works better at the higher frequencies i.e.. 130 vs. 17 MHz and 440 vs. 151 MHz etc.
All the base station operator has to do is point the antenna (the end that has the shortest elements) at the receiving radio, be it a fixed station or mobile. Knowing the exact compass point is even better. As you stated liberal use of pre-arranged codes and frequency changes accompanied with pauses (time outs in transmissions) after frequency changing is helpful especially if the radios are dual band models where cross band transmission is employed. [Where station A transmits on frequency x and receives on frequency y, and meanwhile station B transmits on frequency y and receives on frequency x. Thus anyone intercepting the transmission will only hear one half of the conversation.]
I would venture to guess that there will not be many spread spectrum analyzers floating around the countryside during a meltdown but there will be scanners aplenty so I strongly recommend folks possess dual band radios. Just remember: Keep the microphones unplugged until needed. – Joe from Tennessee
Merry Christmas Jim,