Well the things I did in the last post that I thought fixed my RFI issues and the DSAB network drops did not fix the problem. Over a few days between trips I have worked on this issue and finally solved the problem today.
I isolated the issue to the AP74 and HS34, I would watch the DSAB connection when transmitting on the radio and if long enough both HS34 and AP74 would drop offline. The servos never dropped so I knew my issue was not with the proximity to the VHF antenna. I remembered when I wired up my AP74 I had an extra wire and instead of cutting it I tied a loop; this loop is right behind the radios.
I pulled the instrument panel to get to this wire, while there I saw a wire from the Safety Trim harness that I had not used; it was a power wire for a trim indicator. This wire was not needed because the trim indicators are built into the Dynon EFIS. I pulled out this wire and removed it from the DB25 of the trim system. I then removed the loop in the wire for the AP74 and cut it short and made a more direct route to the DSAB hub. I then re-installed the instrument panel; this was good practice since I will need to remove the main panel to rivet on the top skin so now I know what is involved.
I then tested the transmissions on a few frequencies and no drops in the DSAB network! I had to leave on a trip tonight so I will do more extensive testing when I return.
NOTE: Returned from my trip and tested all major frequencies and no drops in the DSAB. Not sure what was the fix: AP74 wire, unused indicator power wire or the reseating of the radios. I was able to get a radio check with SEA center from inside the garage; I think the repeater is on the fill behind the house.
