This version of the single rate wideband test modulator contains an input r=1/2 K=7 convolutional encoder. The polynomials are G1=1718, G2=1338 with G2 delayed 1/2 bit. One of two separate data and clock inputs at ECL levels may be selected. The information rate may vary up to 25 Mb/s with corresponding transmission rate up to 50 Mb/s. The modulator is an OQPSK modulator centered on 720 MHz. The modulator output is amplified and routed through a programmable attenuator to the rear panel output to provide adjustable output levels. One may locally control and monitor status via the front panel or remotely through the IEEE 488 interface. This unit is used for earth station loop back testing or for performance testing of the corresponding demod/decoder.