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Transponder antenna, ADS-B... TSO?d?

jbDC9

Well Known Member
To the RV and ADS-B brain trust...

Question; does a transponder antenna mounted on an experimental aircraft need to be TSO?d to operate with the ADS-B system?

Here?s our scenario; we (owner group) have a Experimental Exhibition category T-28D. Current transponder is a KT-76A with a ratty old King blade antenna that needs replacing; my inclination is to get a DeltaPop antenna for $70 to immediately replace the antenna, but sometime within the next year we?ll being doing the ADS-B upgrade, most likely a Garmin 335/345 transponder. Will a GTX345 be legal to use a non-TSO transponder antenna? Our avionics guy just did a VFR xpdr check and says to skip the DeltaPop antenna and get a Comant or Rami instead. What say youse guys?
 
For EAB aircraft, the FAA has allowed that ADSB devices must meet ?the performance standards? of the TSO, but do not actually have to have been granted a TSO. So your answer is no, a TSO?d antenna is not mandatory.
 
Our avionics guy just did a VFR xpdr check and says to skip the DeltaPop antenna and get a Comant or Rami instead. What say youse guys?
Six of each or 1/2 a dozen, really it doesn't matter. FWIW in 99% of our applications even the "el cheapo" TED antenna will work just fine, but the Delta POP does look better on the airplane.

:cool:
 
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...even the "el cheapo" TED antenna will work just fine, but the Delta POP does look better on the airplane.
It's not really a matter of looks. The el cheapo antennas are cut for the 1030-1090 MHz transponder band and performance is degraded at the 978 MHz ADS-B band. The blade-type antennas are broadband and perform well at both transponder and ADS-B frequencies. If you're using a UAT like the Garmin GDL-82, you really want the broadband antenna.
 
The Delta Pop antenna works perfectly fine for my Uavionix ADSB installation and I have yet to hear from anybody saying otherwise

erich
 
It's not really a matter of looks. The el cheapo antennas are cut for the 1030-1090 MHz transponder band and performance is degraded at the 978 MHz ADS-B band.

TED makes an ADS-b antenna, its just a bit longer than there transponder antenna to get it closer to the 978 MHz
 
TED makes an ADS-b antenna, its just a bit longer than there transponder antenna to get it closer to the 978 MHz
EXACTLY. Besides, unless you are in a lab with sensitive measuring equipment, for our application the difference is so small 99% of us of won't be able to tell.

:cool:
 
Thanks for the feedback! I was thinking the same, that using the Delta Pop blade antenna would be fine, but when an avionics guys says otherwise... it made me wonder.
 
Antenna

I've installed several ADS-B brands, Garmin tells which antennas, they all have worked. $25 or so for ball type, $100 or so for blade.
 
I have King 76A and just replaced the King blade for Delta Pop, then had Transponder and Pitot Static check with Russ @ Palmetto Avionics in Greenwood SC....PASSED. YMMV
 
TED makes an ADS-b antenna, its just a bit longer than there transponder antenna to get it closer to the 978 MHz
Yes, that's true. My problem was that my GDL-82 broadcasts both on 1090 and 978 so I needed the broadband antenna which would cover both bands. Delta Pop makes a blade type UAT antenna as well as the transponder version. I corresponded with him about which would be better with the GDL-82 and he told me "Either one will work just fine". I chose the transponder version and it IS working well.
 
Yes, that's true. My problem was that my GDL-82 broadcasts both on 1090 and 978 so I needed the broadband antenna which would cover both bands. Delta Pop makes a blade type UAT antenna as well as the transponder version. I corresponded with him about which would be better with the GDL-82 and he told me "Either one will work just fine". I chose the transponder version and it IS working well.
Exactly what we said. ;)
 
Thanks for the feedback! I was thinking the same, that using the Delta Pop blade antenna would be fine, but when an avionics guys says otherwise... it made me wonder.

Well, unless the avionics guy has hard data and is familiar with the EAB world, I would get a second opinion.
 
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