Yaesu FT-7800 Weather Satellite Mod
FT7800 can hear weather satellites NOAA (15, 17, 18 and 19), but getting nice pictures is difficult due to narrow badpass IF filter. This can be "fixed" by inserting a small IF module with no ceramic filter, only a resonant coil on 455 kHz, which allow to get the 30 wide khz audio at the exit point. Insering this module does not alter the transceiver parameters because this new audio signal is collected on a different output point, with no connection with the original receiver.
Pictures 1 and 2 shows the connecting point (455 kHz out) from FT7800 receiver IC.
Pictures 3,4 and 5 shows module construction details.
The module is powered from pin 5 of the audio amplifier. Audio wire is taken out through the gap made for fan wires.