SV-XPNDR-262 non-compliant?

AWieder

I love flying!
Joined
Apr 12, 2015
Messages
5
I'm confused by the references to equipment "Class 1" on the Dynon website and the disparity with FAA information on ADS-B equipment.  Specifically, the Dynon product page states:
"U.S. ADS-B OUT Compliance Information: The FAA ADS-B "final rule" only allows the higher power Class 1 transponder to be used as an ADS-B Out transmit device for ADS-B Out mandate compliance on or after 2020." 

I couldn't find any reference to a "Class 1" in either the final rule or TSO-C166b.  The final rule states that a Mode-S ES transponder must have minimum power of 125 Watts and:
"Aircraft operating in airspace designated for ADS–B Out, but outside of Class A airspace, must have equipment installed that meets the antenna and output power requirements of either:
(i) Class A1, A1S, A2, A3, B1S, or B1 as defined in TSO–C166b; or
(ii) Class A1H, A1S, A2, A3, B1S, or B1 equipment as defined in TSO–C154c, Universal Access Transceiver (UAT)
Automatic Dependent Surveillance–Broadcast (ADS–B) Equipment Operating on the Frequency of 978 MHz."

TSO-C166b states the transmitter could be Class A (A1, A1S, A2, A3) or Class B (B1S, or B1) as defined in RTCA/DO-260B.

The copy of RTCA/DO-260B I found lists A1, A1S, A2, B1, and B1S all having 125Watts minimum transmit power.  Class A3 is 200Watts.

Since the Trig TT21 and SV-XPNDR-262 have 130 Watts per both companies websites...why don't they comply?  Where is "Class 1" referenced by the FAA?  What am I missing? 
 

dynonsupport

Dynon Technical Support
Staff member
Joined
Mar 23, 2005
Messages
13,226
FAR 91.227 (b) (2) (i) refers to TSO-C166B, which refers to DO-260B, which says that ADS-B Class A1/B1 requires 125W at the antenna.

It's almost impossible to do a transponder install where a transponder with 130W at the transponder connector only loses 5W before it's radiated. Thus, we don't believe the 130W transponder ever complies with 91.227 once installed, so you need the 250W transponder.

On our transponder page we do list the compliance more directly:

http://www.dynonavionics.com/docs/SkyView_XPNDR-26X.html

Compliance: ETSO 2C112b Class 1 Level 2els, ETSO C166a Class B0, TSO C112c Class 1 Level 2els, TSO C166b Class B1S
 
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