HI David, just an update on the PPM board situation:
We were working on an updated version of the DIYDrones PPM Encoder v2 (
https://store.diydrones.com/product_p/br-ppme.htm), which was itself an update of the Paparazzi PPM Encoder Board (
http://paparazzi.enac.fr/wiki/ATmega_PPM_Encoder_Board).. isn't open source hardware cool?
Anyway, as you are probably already aware, the goal of all of these boards is the same, namely to combine the 6-8 separate servo outputs from a regular receiver (AM, FM, DSM, etc etc) and combine them (actually REcombine them) into a single signal. This single signal can then be efficiently read in by Lia, Lisa, or other autopilot boards.
Our original plan was to use these with the FlySky CT6B TX/RX we include with Mochas, but it turned out that the CT6B RX was itself already outputting a single combined output on the normally unused signal pin on the BAT/BIND channel. Since PPM boards are neither free nor weightless, we put our design on hold and went the direct route of just connecting the signal from this pin directly to Lia.
However, there shouldn't be any hardware issue preventing the use of the DIYDrones PPM Encoder v2 with any radio/receiver combo and a Lia or Lisa.. but since radios can vary drastically, Paparazzi needs a "radio file" describing your radio's behavior (eg, channel order, minimum, center, and maximum command values, normal/reverse channel sense, etc). There are a 30+ of these already included with Paparazzi, so yours may be all ready to go, or you might have to modify one to get your setup working - check out
http://paparazzi.enac.fr/wiki/Radio_Control to see what's involved.
We have one of the DIYDrones boards and will get it connected up to see exactly what it outputs, and will update here and/or on the Paparazzi wiki with our results. Or, have a go yourself and let us know what you find out!

Cheers,
//Jeff