Re: Power consumption of the Futaba 9C with various modules

Doug McLaren wrote: 
I finally got one the 9C synthesized modules, and people had talked
about the power consumption of them, so I went ahead and measured it.
(Well, I measured current consumption, but if you really want power,
assume 10 volts.)

9c with no module at all 77 mA
with Futaba synthesized module, antenna down 257 mA with Futaba synthesized module, antenna extended 287 mA with 50 mHz module, antenna down 235 mA
with 50 mHz module, antenna extended 200 mA
with 72 mHz module, antenna down 160 mA
with 72 mHz module, antenna extended 214 mA
with Hitec Spectra module, antenna down 311 mA
with Hitec Spectra module, antenna extended 280 mA

I was surprised at a few things --

   -- that the 9C itself used so little power
   -- that some modules used more power with the antenna down. and some
      used more power with the antenna up, and that the two non-synthesized
      modules differed in that respect.

Readings were taken in my garage, so the readings outside, especially
with the antenna extended, may be slightly different.

The power consumption change with antenna in/out shouldn't be a surprise. The power consumption with antenna up vs. down depends on the details of the output amplifier circuit, not on whether the frequency is generated with a crystal or a synthesizer.

The amount of power consumed by the frequency synthesizer vs. a crystal oscillator should be on the order of a few milliamps. This difference will be swamped out by the hundreds of milliamps consumed by the output amp as it does it's job of generating RF so you can drive your plane.

It is a nice touch to have the power consumption go down with the antenna down -- hopefully this means that it's being more gentle to the final amplifier transistor.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
.

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