Garmin?s new GAD 27 interface module pairs with G3X? Touch to streamline (11/18/15)

[Draker]

Originally Posted by g3xpert

The most common way to power the PFD (GDU 4XX), ADAHRS (GSU25), and Engine Monitor (GEA24) in a system using the GAD27 conditioned power (keep alive) output is to wire the Power 1 pins on each to the aircraft main power bus and the Power 2 pins on each to the GAD27 conditioned power output.

When this is done, main bus voltage drops which occur during engine cranking will not affect the PFD/ADAHRS/Engine Monitor which are up and running before starting the engine. This, of course, also maintains the GPS fix that the PFD may have already established before you started the engine.

I'm reviving this thread to ask for more info about the GAD27's "keep alive" conditioned power output. Is the use case for this only during engine cranking, or can it also double as a "poor man's" backup battery?

In other words, in the event of an in-flight alternator failure, is the GAD27's conditioned power output appropriate for keeping critical electronics at +12V for an extended duration or is it only suitable for momentary low-voltage conditions?

[g3xpert]

Originally Posted by Draker

I'm reviving this thread to ask for more info about the GAD27's "keep alive" conditioned power output. Is the use case for this only during engine cranking, or can it also double as a "poor man's" backup battery?

In other words, in the event of an in-flight alternator failure, is the GAD27's conditioned power output appropriate for keeping critical electronics at +12V for an extended duration or is it only suitable for momentary low-voltage conditions?

Hello Ryan,

The conditioned power output from the GAD 27 is only suitable for brief low-voltage conditions such as seen when starting the engine. It is not a replacement for any required backup battery. Most customers will use one or the other, but not both.

Thanks,
Steve

[Draker]

Perfect. That really helps!

[DRMA]

Originally Posted by g3xpert

Hello Ryan,

The conditioned power output from the GAD 27 is only suitable for brief low-voltage conditions such as seen when starting the engine. It is not a replacement for any required backup battery. Most customers will use one or the other, but not both.

Thanks,
Steve

I am using both the IBBS battery backup system and the GAD 27 in my panel. I have PFD-1 connected to the battery, along with the GMA 11, GTN 650, ADAHRS, etc, but then connected the MFD to the GAD 27. This way I keep the current drain on the IBBS within specs, while being able to keep the MFD from re-booting during engine start.

Just an idea for your consideration.

[snoop9erdog]

Dave,
I?m curious, with no backup power pin on the GTN, how did you connect the GTN to the IBBS? Did you use TCW?s wiring and utilize the passthru?

[DRMA]

No, I want the TCW IBBS to be a truly separate source (i.e. if the pass thru fails, the avionics will still receive power from the normal electrical system.) I isolated the 2 different power supplies by installing a diode in each source lead just ahead of the power input to the GTN 650. I used relatively large SR1045-TP Schottky 45V 10A R6 diodes from DigiKey (P/N SR1045-TPMSCT-ND). I did the same for one other supply, I think it was the GTR 200R radio (don't have my wiring diagrams in front of me to confirm).

[snoop9erdog]

Thx for the info Dave. Besides the PFD 460, GSU 25, and GEA24.....I'm contemplating placing my GTN 625 and GAD 29 on the IBBS as well. But I also want the IBBS to be a separate system. I'm not sure how to do the diode thing for secondary power...do you mind sharing what you did in case I go that route?

I also like having only those three key items on the IBBS as it would surely power those items for maybe 2 hours

[DRMA]

Ed,

If you will send me your email address via Private Message on this board, I will email you a page from my wiring diagrams that shows where to place the diodes for isolation between the 2 power systems.

Think of a diode like a check valve - current will only flow through the diode in one direction. The diode blocks power back-flow should one of the 2 power circuits become shorted to ground or go off-line.

[phgeyer]

Originally Posted by N834ST

I am retrofitting the G3X into my RV-7. Is there a way to use my current trim/flap position indicators as well as the G3X? Not sure how I would wire it with regard to the +5v from the GEA 24.

Anyone done this?

Thanks!

I have not seen a reply to this question. I am also interested in continued use of the ray allen indicators while controlling the servos with the GAD 27.

[g3xpert]

Originally Posted by phgeyer

I have not seen a reply to this question. I am also interested in continued use of the ray allen indicators while controlling the servos with the GAD 27.

Good Morning,

The GEA 24 will provide 5V to each Ray Allen unit individually. There are drawings for this specific interface on page 30-6 of the AL revision of the G3X Touch Installation Manual.

Thanks,

Justin