Electrical System

Mounting the Radio

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After sitting in the cockpit trying different locations I decided to mount the radio on the dash. I had to make a small spacer of 1/8″ ply because the back of the radio is recessed where the screws are located.

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Spacer for radio
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Back of radio

It fits well in this location with the modified Yaesu adapter I made.

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Radio mounted

This location did block one of the two switches I had on the dash and the one unblocked switch cannot have a cover because the radio adapter keeps the cover from opening. I plan to enlarge the blocked switch hole to feed the radio wires through the dash. I’m undecided on what I want to do about switches. I really only need one switch but if my generator fails it would be nice to be able to turn off non-essentials to preserve battery power.

At this time I will go with just one switch next to the starter key. The dash is looking really nice so far.

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MiniMax dash with radio mounted
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Yaesu Radio Adapter

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The Yaesu radio adapter for my MicroAvionics powered radio interface sucks. It sticks straight out the side blocking access to other parts of my dash.

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MicroAvionics MM014DD same as Yaesu CT-91A adapter

The Yaesu came with a really nice adapter but it was made for general aviation connectors making it useless for the MicroAvionics powered radio interface. So I cut the general aviation connectors off of it.

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Yaesu SCU-15 headset adapter with headrest ends cut off

Dropped by Radio Shack and picked up a 1/8″ female stereo cable connector. The white wire connects to the tip and of course the braid connects to the ground.

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1/8" stereo female jack

The other connector is a 3/32 and the Shack did not have any so I stole the connector from the MicroAvionics adapter. Red wire to tip, black to center and braid to ground.

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3/32 female stereo jack

I cut down one edge of each connector to ensure they both fit onto the MicroAvionics MM005 interface cable.

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Cut down to fit MM005
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Connect adapter to MM005

Before:

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Yaesu FTA-550 with MicroAvionics MM014DD

After:

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Yaesu with modified SCU-15 adapter

Push to talk

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The push to talk button will allow me to transmit on the air band radio. Having a convenient way to transmit and making it look attractive is my goal.

I used my hobby knife to cut a pocket in the plastic plug that goes in the top of the control sick.

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Control stick cap

The switch was installed and attached to the plug.

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PTT switch

I drilled a small hole near the bottom of the control stick.

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Hole for wire to exit

Added a grommet for the wire to exit.

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Rubber grommet

Finished product looks good.

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Finished control stick with PTT switch

Instruments and Switches

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With the fuselage nearly completed I started working on the gauges and electrical system. Using some 1/4″ plywood I started laying out the dash.

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Once everything was in place the dash was cut out. Three corner blocks were made and bolted to the dash board using threaded inserts. Wax paper separated the blocks from the board to ensure only the blocks get glued.

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After a little bit of sanding to get the dash sitting at the correct angle the blocks were glued to the fuselage.

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Empty dash

Since the dash is not glued in place I can easily removed it and  replace it should I ever decide to modify the layout. Mounting the components was much easier with it removed so the three bolts were removed.

The toggle switches were not long enough to fit through the 1/4″ plywood so I used the router on the back side to remove some material in that area.

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Cutout for switches

All of the switches were mounted.

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Switch connectors
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Toggle switch covers

The two red ones will control the redundant magnetos. This allows me to turn each off, one at a time, to ensure each ignition system is working before flight. To stop the engine both switches will must be flipped at the same time. The blue ones will control items like the radio, auxiliary power etc.

The next component to install is the engine information system (EIS).

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Engine information system

This monitors engine temperature, fuel level and various other important things. If it detects a problem it will alert the pilot by activating the warning light.

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Warning light

Next I installed some USB charge ports and a cigarette lighter port. This should be sufficient to power any accessories.

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Power for accessories

The keyed switch needs a small block glued to the back of the dash to keep the switch body from rotating.

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Block to help support ignition switch

This switch controls the master power and engine starter.

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Keyed ignition switch

Last are the two most important gauges. The air speed indicator. The airplane needs about 28MPH just to fly and is designed for a top speed of 90MPH. Flying too slow or fast could be fatal.

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Falcon air speed indicator

The altimeter simply tells us how high, above sea level, we are. Airspace restrictions can vary by altitude plus there might be mountains or towers requiring an altitude change.

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UMA non-sensitive altimeter

The dash was bolted to the fuselage to check the fit. Hooking up wires and tubes will be rasy with the cockpit opened.

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Back side of dash

It looks good with the cockpit closed.

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Dash with canopy closed

I will also have a compass but it’s currently on a UPS truck somewhere. When it arrives I plan to mount it on top of the canopy deck in the center.