Bob WB4APR wrote:

The use of speaker/mic connections(with pre- and de-emphasis) and direct modulation and discriminator demodulation can each have optimum performance. But there are always problems when crossing between the two. BUT, it IS possible to adjust on the transmit side for a compromise between the two and then receivers of each type can decode pretty good.

Though maybe 1% of hams go to this trouble. Packet radio is NOT Plug-N-play. The transmitter must be adjusted for optimum waveform!

Wayne W9AE replies:

Nearly every mobile/base ham transceiver manufactured in the last 30 years has a "packet data" port on the rear. I doubt that very many hams use microphone and speaker ports for packet data.

Wayne Estes W9AE Oakland, Oregon, USA, CN83ik