The tuner requires RF power to tune. A transmitter in USB or LSB outputs no power when there is no modulation. Some LDG tuners can tune while you re talking on SSB. If that does not work, transmit a constant carrier such as AM or FM. Some radios do not put out any RF power when the PTT is pressed and the mode is CW. They may even show that the TX is on, but no RF power will be transmitted.