by RCModelReviews » Tue Feb 08, 2011 10:55 pm
The current-draw of a transmitter depends on several things but mainly, the type of regulators it uses.
Some systems use linear regulators, some use switch-mode regulators.
The former will draw more current than the latter -- sometimes a lot more.
A good example are the current DSSS modules from Corona. They have a linear regulator so they have quite a high current draw. By comparison, the FrSky modules have a switch-mode regulator so they draw less than half the current.
The same goes with the transmitters themselves -- those with switch-mode regulators will draw less than those with linear ones.
I haven't done a head-to-head comparison but I do know that the days when you only got 60-90 minutes from your transmitter from a full charge are gone. Most 2.4GHz systems will give many hours of flying (especially if they have a lithium pack). I charge my own 9X only once a month at most -- and I tend to fly a lot when I can.
My JR 9XII (9303) now gets twice the time per charge since I replaced the JR 72MHz synth module with a FrSky 2.4Ghz module. That's partly because the 2.4GHz systems don't need so much power (100mW versus over 500mW) and partly because the FrSky has a switch-mode regulator.
A good way to tell if *your* 2.4GHz system has a switched or linear regulator is to feel the module or the back of the case. If it's getting warm after extended use then it's probably got a linear regulator. Switch-mode regulators should run cool because they're not wasting power in the way the linear ones do.
RCModelReviews.com, just the facts.