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

Ed Cregger wrote:
> "Poxy" <pox@xxxxxxxxxxxx> wrote in message
> news:o4eGe.65508$oJ.44830@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> 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.
>>
>> A couple of years ago I was playing with my old JR radio looking at
>> the magnitude of the carrier on an oscilliscope - I ound that as I
>> varied the antenna length, the strength of the signal varied. The
>> strongest signal was
>> achieved at about 2/3rds extention, and at that point the radio's
>> power consumption was lowest.
>>
>> I should try the same experiment with my newer radio...
>>
>>
>
>
> Don't forget that the radiation pattern changes as you vary the
> length of the antenna. It is possible the the length providing the
> best match/least current consumption, might not be the best pattern
> for flying, though I doubt there would be any major consequence, even
> in a worst case scenario.

I'm no RF expert, but I'm pretty sure that the antenna on a radio is a
simple dipole with a correspondingly typical radiation pattern. I suppose it
might change shape with antenna length. That said, I've got no plans to go
flying with my antenna at half-mast - as it stands I can barely see my plane
long before it's out of range.



.

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