A test apparatus and method of testing a DUT are described. The apparatus includes a receiver and transmitter path each having a pair of switches that switch between a bypass position and a direct position. The bypass position is used for low frequency signals communicated through the apparatus. The direct position allows higher frequency signals to be double converted by upconversion to an IF signal and bandpass filtered before being downconverted to a predetermined frequency. Both variable and fixed LO signals are used to convert the double converted signals so that the same IF may be used independent of the higher frequency signal received or transmitted. Bandpass filtering is applied before and after amplification of the IF signal. Lowpass filtering before and after the double conversion use LPFs of different cutoff frequencies.