Web, I'm planning my panel now on my rebuild and would like to set everything up over the winter. Can you recommend a transponder / ADS-B set up for minimal compliance and cost? I already have a good Becker 4201 Com and am thinking about the transponder requirements for ADS-B compliance. I am thinking of using a Trig TT22 transponder and Uavionix Skybeacon. However Skybeacon says it can be used 'with any mode C or S transponder' so does that mean I can pick up a used mode C Becker and still be compliant? There's something else to do with class 1 or 2 so I'm not sure.
Do you see any less expensive way to set up for the ADS-B compliance starting from scratch? Maybe best to just equip with a good transponder for now since almost all of my flying is out of ADS-B required areas.
Units like the Skybeacon or the GDL 82 use the existing transponder and piggy back a signal onto it's output. But do your homework before you start spending money. Carefully read the specs called out in 91.225 and 91.227 AND the related TSO specs. There are minimum power requirements for using an existing transponder. And if you plan on flying outside of the US your system needs to operate on 1090 mhz. 'UAT' systems such as the Skybeacon transmit on 978 mhz. This is legal only in the US under 10K.
As far as the installation/interface procedures go, you need to find out if the system you wish to install has it's own GPS WAAS position sensor or if it requires a signal from another source. Also some UAT's interface with the transponder electronically through the transponder antenna. Other units require the transponder coax cable to be routed through the UAT. Still other units use RS 232 data lines to interface with the transponder.
--THERE IS NO SINGLE WAY TO BUILD AN ADS-B SYSTEM--
As to your specific question of using the TT22 and a Skybeacon; No. The TT22 is an 'extended squitter' transponder. That means that it is interrogated on 1030 mhz and transmits on 1090 mhz (and at 250 watts which is Class 1) . It also incorporates the extended squitter message with all the required information for mode S and ADS-B. The only thing it requires is a GPS WAAS location signal to make it fully ADS-B out compliant. You can use any certified, GPS WAAS signal for this purpose as long as it can be sent to the TT22 on a data line (RS 232). If you want to stay small, Trig has a WAAS unit called the TN-70 for just this purpose.
The Skybeacon is a UAT unit that transmits on 978 mhz. It also has a built in GPS WAAS position sensor. When installed it puts the extended squitter message and the GPS position onto the existing transponder's signal. That makes that system ADS-B legal in the US, at 10,000 feet or under.
For most Cub type installations, I usually recommend the TT22. Not the cheapest but one of the most compact setups. If you never fly outside the US, a mode C Becker and a Skybeacon will work fine.
Web