A $5 Mode V/S Adapter Using a Sub-Harmonic Mixer

摘要

The recently launched AMSAT Echo Satellite, AO-51, introduced the use of transpondermode V/S. Mode V/S uses the 144 MHz (VHF) band for the uplink and 2.4 GHz (S-band)for the downlink. Equipment for this new mode is a challenge because most commonlyavailable S-band down-converters use VHF for the intermediate frequency but thecurrently available transceivers cannot use VHF for both the uplink and downlink at thesame time. Operating on this new mode has required using a second radio or buying aspecial down-converter that can use the UHF band for the intermediate frequency.This paper presents an alternative solution that is simple and inexpensive: an adapterthat will convert the output of an S-band down-converter to the 6-meter band. This deviceenables most satellite and many non-satellite transceivers to work mode V/S since theycan receive the downlink on the 6-meter band while using the VHF transmitter for theuplink. The adapter employs a sub-harmonic mixer circuit along with a standard TTLclock oscillator and can be easily constructed for about $5 in parts.