Personally I've found that powering any kind of Tx via a separate voltage regulator (or UBEC) introduces less noise in the AQ sensors, especially MAGs. This is easy to spot in logs/telemetry. Maybe the extra noise gets filtered out or is otherwise insignificant, but I figure it can't be helpful. Even just a ground+signal connection between AQ and Tx introduces some noise, but less than if power is also routed. YMMV, but I've seen this on all 3 of my AQs and with several different BT and 3DR transceivers. With BT it's fairly minor (can see the LED blinking in the MAG plots for instance, but not much else), but with the 3DR things were worse in my setup.
Might be worth some experimenting. Here are a couple screenshots I dug up, to illustrate.
-Max
- BT module powered from AQ - module on (LED blinking), then off (disconnected), then on again (LED blinking) then BT connects at the end (LED steady on).
- BT module powered via external vreg. - off/on/connected, no obvious difference in plot.