Originally Posted by maus92
Replacing the VP-X is not the solution.
I have a similar setup, except mine is a G3X. What CB value are you using for the transponder, what is the draw for the transponder, and is it the only device on the circuit? What gauge is the wiring to the transponder? How many power leads are there for the transponder? (Mine has two, but are fed from the same circuit atm.) Is there any correlation between the circuit tripping and the ack reply by the transponder? What is the ammeter telling you when the see the ack reply? Are you seeing any voltage spikes? What do the Dynon logs say? Have you checked the transponder antenna and cabling? I always check everything, even tangential stuff when I troubleshooting just to get a baseline.
Do you have a spare alternator you can swap in?
Couple of answers. I am using:
a Dynon SV-XPNDR-261
with whatever setting Dynon configures it by default.
It's the only device on the circuit. Wire is 18G with a single lead. Breaker is set to 3A based on Dynon install guide it's on a 5A VP-X port.
I did check the trasnsponder cabling to the Dynon as well as the power leads (multiple times). Didn't check the antenna cable but it's about 1 foot long entirely visible and I didn't see any external damage. Will add that to my list.
Typical current << 0.5A . Don't recall what the spikes are during ACK replies and if that correlates. Something else to check.
Now one thing is that it worked flawless for 4 years. So something changed recently and I didn't change anything ... .
I don't have voltage spikes tripping the VP-X but that doesn't mean there aren't any... . They could be to short to trip the VP-X. I am wondering actually if that is what's going on but I don't have the correct instrument to measure those... .
Good tip with the Dynon logs. I didn't even think about those... . Wonder if the VP-X has any logs too.
I don't have a spare alternator will see if I can borrow one at the airport.
p.s. and yes replacing the VP-X it is not an option... . There are so many benefits to this setup... . It's like saying to somebody who's fuel injector is acting up why don't you fly a glider ... . Never had engine problems while flying those ... .