[aprssig] 8 hour Backup Power Rule

Steve Noskowicz noskosteve at yahoo.com
Tue Mar 18 02:56:20 EDT 2008

--- Rick Green <rtg at aapsc.com> wrote:

> On Mon, 17 Mar 2008, Steve Noskowicz wrote:
> >    Transmitter power is quite low in many cell sites - many under 10 watts
> > into 17 db gain antennas.    That 300+ amps at 24 (or 48) volts (7kW++)
> doesn't
> > all go out the antenna and, therefore, heats the site.  100 channels at 10
> W
> > ea. is only 1kW.
>    That implies ~6KW of heat to be pumped out of the building.  

    That was just a simple RF example meant to give some idea, not a full
analysis -- I did mention that there was other stuff.  I don't remember how
much the other parts of a system use, but they're processers and the ammeters
on the Loraine rectifiers always showed big numbers.  The point was just that
the batteries size adds up quickly.

>... 70% of your power bill can go to running your computers, and 30% 
> will have to go to the A/C unit.

   One thing with A/C is that it takes less than a watt from the grid to pump a
watt of heat.  The only place you seem to get something for nothing.  

>    It seems to me that the bits you're spitting into a fibre line or three, 
> no matter how fast, don't contain a whole lot of energy, 

    For sure.  The intent was that the box that does it also makes heat.

> I don't blame the cellphone companies for balking..... snip.. when you 
> consider some 300,000 cellsites, 

   That's the  bigger issue than a mere $15,000 (or whatever) in batteries for
one site.

>... hidden within the large crucifix ...behind the ...freeway sign ...
> lightning-bolt sculpture.

   If I could spell ubiquitous...

73, Steve, K9DCI

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