# Cheapest solution for Mode C Transponder and ADS-B?

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#### Toobuilder

##### Well-Known Member
HBA Supporter
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Where is everyone purchasing their "used" avionics" from?
VAF, of course. Many of them will redo an instrument panel as soon as the next new shiny object is released.

I have plenty of hand me downs populating my panel, courtesy of the "need to be first" crowd.

#### Rik-

##### Well-Known Member
VAF, of course. Many of them will redo an instrument panel as soon as the next new shiny object is released.

I have plenty of "hand me downs" populating my panel, courtesy of the "need to be first" crowd.
Thanks, one of the planes I looked at last month has zip for a panel and zip for anything modern.

I was told that the Uavonix echoUAT will work with nearly any transponder but the one in this project is OLD... Something newer, easier or better is always good.

#### SamP

##### Active Member
I saw this DIY Mode C transponder awhile back. Has anyone put it together? There probably are legal issues

#### Built2Fly

##### Well-Known Member
I saw this DIY Mode C transponder awhile back. Has anyone put it together? There probably are legal issues
Very interesting work. RF work to me is a bit like black magic. This guy is making some very interesting stuff. Thank you very much for the link, Sam.

#### pfarber

##### Well-Known Member
You shouldn't need a serial to gray encoder with the GTX327.

From this post: https://vansairforce.com/community/showthread.php?t=166994
"I connected the Encoder Out wire from the Dynon to Pin 19 of the GTX-327 ... I programmed the ALTENC setting on the Dynon to "Format 4" for the GTX-327, and on the transponder, set "RS-232 Input CHNL 1" to "Icarus" per the manual. "

Finn
I'm not sure what that neon green tube is for, but having it rub against the metal cutout it's routed through does not install much confidence in its longevity.

#### Daleandee

##### Well-Known Member
Garmin 327 with uAvionix SKYFix and the box. Only needed to install the GPS antenna on top and the stick and ball on the belly. Now I have IN/OUT with no wires hanging around. Sound installation.
I know this thread is a little long in the tooth but I finally picked up enough cans from the side of the road to afford a uAvionix echoUAT+SkyFYX-EXT bundle:

I'm currently running a Garmin 320A transponder (certification was due & completed this month). This should be a simple install with the GPS antenna on the top and the Echo UAT antenna on the belly. Part of what I had to find out was the cable from the Echo unit to the lower antenna is not provided. I ordered a 3' RG400 Silver Plated SMA Male to BNC Male coax Cable. I haven't received the package yet but I understand it comes with a short SMA male to BNC female connector (same as on the UAT antenna) so if you use that cable you would need a coax with both ends as a male BNC. My thought was that buying one cable with the SMA male & BNC male I would eliminate one connection and perhaps save a little weight. I may video the install as there isn't a lot of information to be found on the SkyFYX-EXT mounting when used as part of this bundle.

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#### pwood66889

##### Well-Known Member
What'd it cost you all-up, Dale?

#### Turd Ferguson

##### Well-Known Member
I saw this DIY Mode C transponder awhile back. Has anyone put it together? There probably are legal issues
In the US a mode A/C transponder has to meet environmental and performance standards of
TSO-C47c.
Other than that, the electronic test equipment to build and test will likely exceed the cost of several transponders.
I have no idea what language they speak in Slovenia (Slovene maybe?) so just reading the plans would likely be a showstopper for me.

#### Daleandee

##### Well-Known Member
What'd it cost you all-up, Dale?
We're doing the install this weekend so obviously I don't have an installed price.

The Garmin 320A transponder and encoder unit (which just passed its two year certification) was gifted to me by a good friend that took it out of his Rockwell Commander and gave it to me. Even more than that he made the harness for me as I eliminated a lot of weight by not using the tray that came with it. He is very good at electronics having once worked at a high level position doing such.

The UAVIONIX Bundle EchoUAT with SKYFYX-EXT all in one receiver unit is sold most places for $1399.00. Adventure Pilot (iFly GPS folks) had a sale for$50.00 off. I also bought a single coax to go from the Echo unit to the UAT antenna for 19.79 & tax but no shipping. So at the end of the day I should get it done for ~ \$1375.00. That's still good money in my part of the economy but being experimental beats the daylights out of adding ADSB to a certified aircraft.

Nice thing about the Echo unit is that it broadcast both frequencies via Wi-Fi to the iFly 740b for traffic and weather allowing me to remove the Stratux unit I use now. I actually might lose a few grams of weight in the swap. Not sure exactly where these parts are going on the airplane just yet ...

#### Toobuilder

##### Well-Known Member
HBA Supporter
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I have 50 hours over the last 6 months with the Echo /GTX327 setup and no complaints, no issues. Works as advertised.