The first revision of the Arduino APRS transmitter is designed.

The LVDS signal from the SiT9365AC 125MHz clock source is terminated into both inputs of the DS90LV028ATM CMOS LVDS receiver. A level shifter makes this singal compatible as a clock signal for the AD9850 DDS synthesizer that will generate the IF frequency. The IF is then filtered to reduce the harmonic content of the synthesizer's output. The IF signal will be around 19.39 MHz. The other output of the LVDS receiver is buffered, filtered, and amplified by common-emitter amplifiers with 2N2222 transistors in order to form the LO signal. The two signals are multiplied by an ADE-11X+ VHF mixer, whose output is amplified and filtered to remove all but the desired frequency of 144.39 MHz. This signal is then amplified by a CMX901 power amplifier. Impedance matching was taken into consideration.

The current schematic (which is very likely to change) is shown below: