Archive for February, 2009

Rocker switches

Sunday, February 22nd, 2009

The Honeywell AML34 rocker switches I'm using have separate switch operators – that's the part that you actually flip back and forth. I sent them out to be engraved a while ago, and I finally got around to installing them tonight. They look excellent:

These will eventually be backlit by internal LEDs, which should be pretty sharp looking.

The ignition and aux battery switches got the label treatment as well. Of course I didn't engrave the Cessna split master switches, since they're all-in-one units. I'll have to have a placard made to label the master switches and breakers.

I also spent a bunch of time cleaning and organizing the garage, but you probably don't want to see pictures of that.

Headphone jack brackets

Saturday, February 21st, 2009

While working on the audio wiring, I got to the point where I needed to hook up the jacks for the headsets… and realized that I had made absolutely no plans for where to put them or how to mount them. Man, I really wish I had considered the headphone jacks when I was doing all that elaborate panel planning.

There are lots of different ideas about the best place to locate the headphone jacks… I won't repeat all the arguments, but I will mention that in my RV-9A they were in the baggage compartment, which I really hated. On this airplane, I've decided to put the jacks in the traditional location at the lower outboard corners of the panel. To figure out the clearances involved, I got out the air vents and the interior side panels (mighty nice looking, I must say).

I dug a couple pieces of 0.050" alclad out of my scrap bin and bent them into Z-shapes using my new and improved bending brake.

I match-drilled the brackets to the air vent mounting holes, and cut a big hole in the middle of each one.

…but since my biggest Rotabroach cutter is 2 1/2" inches and I needed a 2 3/4" hole, I had to expand the radius with a rotary file.

It's not pretty, but it will be hidden so I don't care.

Two completed brackets for headset jacks. Each one has two holes for the traditional mic and phone plugs, and one for the combined Bose mic/phone/power connector. The odd taper is necessary to provide clearance for the contour of the interior side panel.

Here's a test fit on the passenger side. The jacks are nicely recessed, out of the way but easy to reach. The headset plugs ought to be fairly well protected from being stepped on by clumsy passengers. The bracket flexes a bit when inserting or removing the plugs, but I don't think it's going anywhere. I'll paint it black later.

Here's a view from the other side of the panel. The bracket is sandwiched between the panel frame and the air vent's mounting flange.

Well, now I can actually start on wiring the headset jacks. If I had done a better job of thinking ahead, I could have maybe come up with a better solution for mounting them, but this turned out mostly okay.

Cabin speaker

Monday, February 16th, 2009

Between skiing and trying to get over the resultant and inevitable cold, my weekends have been severely lacking for airplane building time lately. Happily, I did manage to get a little work done today while staying home from work trying to recuperate.

I bought this little low-profile speaker at some point, with the intention of using it as my cabin speaker. Not everybody puts a speaker in (after all, you can't hear it in flight) but I find them useful for listening to ATIS and so forth before starting the engine. Plus, if I have a working cabin speaker I can verify my radio audio wiring without having to make a decision about where I want to put my headphone jacks just yet.

Where was I… oh yeah. I made this little speaker bracket out of a piece of scrap alclad from my junk pile:

The bracket is riveted to the underside of the F-705F channel, slightly to the starboard side of the flap motor housing. I soldered a few inches of wire to the speaker, attached a molex connector, and screwed it to the bracket. The speaker is hidden, but should be easy to hear once I finish wiring it.

By the way, to make this bracket I used my Harbor Freight bending brake, which works 100% better since Scott used his milling machine to round off the sharp corner on the nose of the die. Thanks Scott.

Han Solo gets frozen again

Saturday, February 14th, 2009

Does two years in a row count as a tradition or just an encore? Anyway, this is what happens when you have two geeks who're married to each other and Valentine's Day falls on a weekend… more Chocohans! (follow the link if this makes no sense to you)

We still have the molds from last year, so all we had to do was melt up a whole bunch of chocolate chips:

We have two molds, and we can do a full casting cycle about every 40 minutes. In between is TV and video games.

Half are plain, and half are crispy:

He should be quite delicious… if he survived the freezing process, that is.

Another beauty shot of Mary modeling Chocohan. I'm telling you, this version of Valentine's Day is way more awesome than what they show in jewelry commercials.

During the course of the day we made two dozen Chocohans. Also, our fridge has a lot of booze in it. Who's to say whether or not these two facts are related?

We now return to our irregularly scheduled airplane blogging.

More radio stack wiring

Sunday, February 1st, 2009

I ran the power and ground wires to the second 430, which let me get this awesome photo of the whole radio stack lit up:

I started running wires between the radios and the audio panel using the shield termination techniques describer earlier. Strangely, the GNS 430 has separate "low" pins for the microphone input and comm audio output, but the GMA 347 audio panel only has a single "low" pin per radio. That means you have to splice them together at the audio panel end – you can see in this photo how I soldered one to the other. The joint got covered by heatshrink later on.

At the radio end, the mic key input pin on radio #1 is wired to the transmit interlock pin on radio #2, and vice versa. This tells the non-transmitting radio to reduce its receiver sensitivity when the other radio is transmitting, preventing its input from being overloaded and breaking squelch. If you look closely you can see the tx interlock wire leading off from the PTT pin.

I ran the wires from the comm and nav audio outputs on both radios to the audio panel, and from the audio panel to the radios' mic audio inputs. All that shielded wire is starting to make for a pretty hefty wire bundle. I'll terminate the shield wires later on.

The comm connectors on both radios are now fully hooked up. I need to put on the strain relief clamp thingies still. Once again, I am being a fanatic about labeling stuff – the better to make my life easier when doing future maintenance.

I've started replacing the temporary wire ties in the radio wiring harness with actual tie wraps, so I can keep things neat and tidy.

Wires, wires everywhere. I think I'm doing an okay job of keeping it all organized, though.

These tiny connector pins are very fiddly. Thanks to Mary for the documentary photography.

I know I already showed you a picture of the radio stack powered up, but I really like this one too. So you get to see another one.