Can a PM supply a RFD900?

I have the RFD 900 set at power setting 30 if I’m not mistaken that could max out at 1 watt. Is that pushing the limits on what the GENUINE 3DR PM is supposed to handle? 2.25 amps max it says on 3dr site. Not sure how that is compared to 1 watt. My ohms law is failing me :blush:

It’s also powering a APM 2.5, gps, rx receiver. Servos are on a separate batt source. I’ve ran it all on the ground for a few hours doesn’t seem like a problem but nothing ever fails on the ground :wink: But if it’s even close I suppose I could take it all out of the plane and install a separate 5v supply.

FYI it’s a nitro plane so no esc’s.

Watt = Volt * Ampere. But the RF output power doesn’t tell anything about the current draw of the RFD, so that math is pretty useless here.
RF-Designs product page, however, says:

So - I would give it an extra BEC, just to be on the safe side.

Thanks StefanG for digging that up!

Well… I took the plunge and took everything out of the plane. It’s getting its own 5v supply AND the amp 2.5 can rest on the self I decided to put in my other pixhawk. I really like the redundant power option! If I remove the lipo feeding the PM the pixhawk keeps working via the servo rail feed. Sweet!!! That right there could save the day and I have a lot of work in this balsa plane. No foamy here. I did notice though the servos acted sort of punchy when the PM was disconnected and everything was running via the servo rail feed. Is this what that diode I’ve read about is for that goes across the + & - side of the servo rail??

Not really. The Zener diode takes the edge off spikes which can be caused by big servos. If your servo acts up, there’s probably something wrong with the power supply or if you have digital servos and telemetry, the radio is too close to the servo.

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