6A7 - Modern reserve transmitters are solid-state designs and transmit using only A2 modulation. When measuring transmitter center frequency, what precaution must be taken:

B.Modulation must be reduced to zero to eliminate sidebands

A.Antenna must be grounded to suppress spurious side-lobes

C.Voltage to the PA must be kept at half-value

D.Antenna current must be reduced to about 2.5 uA