Transponder test

[wirejock]

Does anyone know how to test the Transponder?
I have the Dynon SV-XPNDR-261. I want to verify it's transmitting. I don't have anything that reads the 1030/1090 mhz range. For now I have it set to stand by so it won't burn up. No antenna. I do have a watt meter and dummy load.

 

[BobTurner]

Remember that this is a Trig clone (TT22) and is an ADSB-out device, so it may transmit even without being interrogated. While the peak power is around 250 watts the average power is maybe 2 watts. A couple of 1 watt 100 ohm resistors in parallel are an okay dummy load. If they get warm you know it's doing something.

 

[wirejock]

Test

Remember that this is a Trig clone (TT22) and is an ADSB-out device, so it may transmit even without being interrogated. While the peak power is around 250 watts the average power is maybe 2 watts. A couple of 1 watt 100 ohm resistors in parallel are an okay dummy load. If they get warm you know it's doing something.

Should it be turned from Standby to ON and IDENT initiated?
Or some other sequence. GROUND? ALT?

I have several dummy loads and my Bird Wattmeter has plugs for 400-1000mhz in several watt ranges. I would think it would register something.

 

[PaulvS]

SDR

It can be ground tested using a DIY ADS-B test unit based on a SDR receiver dongle (about $30) tuned to 1090 Mhz and some open source (Dump1090) and other free software. I verified my Trig transponder was transmitting the correct ADS-B parameters like SIL, SDA, ICAO code etc. The GPS receiver needs to have a clear view of the sky to pick up enough satellites and there needs to be an antenna connected to the transponder. This gives a thorough test of the transponder including checking for possible interference on the comm radio. I don't believe that a dummy load test would really prove anything...

More detail is contained in this thread:

https://vansairforce.net/community/showthread.php?t=218273