August 28, 2004

I did a lot of wiring today, as can be seen by the size increase in some of the cable runs. Steady progress is about the best way to describe the wiring task. Sometimes though, I have to get away from it and do something else.

Anyways, today’s tasks were to wire in some more of the stack, and start to integrate it into the EFIS1. So, I started with the SL-30 radio. This is a relatively simple affair with the RS232 digital link, only three wires and you have it all! So, now I can control the OBS from the E1, and also select and change frequencies for the radio. I was surprised that it wouldn’t automatically tune the VOR though. Maybe there was a deliberate reason this wasn’t done, or maybe it’s not even possible? I’ll ask on the BMA discussion board.

Also, now the E1 has the ability to use both serial and analogue inputs, so I’ll get to use my Apollo ACU that I’d already cut a hole in the panel for before I found out that I may not really need it…. Doh! Anyways, to make the most of it, I decided to hook up the thing anyways, and use it to switch between external sources to the E1, even though now E1 can do this by itself. I received the Mouser order for the 78pin plug, but when I tried to wire it up, the crimp pins I had were too big for the plug! I guess that’s coz it’s high density, and not a regular D-Sub. So, I ordered some HDP-22 pins.

So here’s a shot of more wiring… You can see the transponder is also in here all connected. I wired it to the E1 too.

Once this was all wired in, testing it out proved a disappointment. For some reason, the xpdr wouldn’t show an altitude. On the xpdr, there’s a D4 grey code input, and the E1 doesn’t have that as an output. I wondered if this was a problem, but later research showed that not to be the case. It’s more likely that my E1 doesn’t output enough voltage to show a signal to the xpdr for the specific grey code channels, which could be down to one of the following reasons… 1. My battery was quite low by the time I checked this out, and thus the voltage to the xpdr from the E1 wasn’t quite high enough, or 2. The E1 needs the amplifier card that some of the earlier models didn’t have. I’m hoping to go down the hangar soon and check it out now I know what to look for, and resolve the issue as necessary.

While I was at this end, I did the A/P disconnect and the AOA flaps down wire. So, that’s the ‘Encoder’ plug on the E1 done. Only another bazillion wires left to run! Here’s the E1 end of the routing….