[Elecraft] Re: Field Day Battery Capacity

[Robert Fanfant]

I use a 75 amp hour marine batter to power the computer & my K2 for the
duration of the contest without a problem!!!
-rob

----- Original Message -----
From: "David A. Belsley" <belsley@bc.edu>
To: <elecraft@mailman.qth.net>
Sent: Monday, April 28, 2003 2:14 PM
Subject: Re: [Elecraft] Re: Field Day Battery Capacity


> Daniel:
>   I don't always work the full 24 hours of FD, but I work a lot of them.
> Two 7 aH batteries are more than enough when running 5w.
>
> best wishes,
>
> dave belsley, w1euy
>
> --On Monday, April 28, 2003 5:00 PM -0400 W5EI@cs.com wrote:
>
> > Daniel
> >
> > If you are using the K2 as a QRP rig, the "jump start" battery might
> > work.   Current drain on receive should only be 250 mA or less (your
> > mileage may  vary).  The Wal-Mart type battery I have is a 19 amp-hour
> > one, so 24 hours on  receive at 250 mA is no problem.  Of course
> > transmitting is going to require  1.0 to 2.0 amps if you stay at 5 watts
> > or less.  The K2 is rated for 2 amps  at 10 watts.  Duty cycle for CW is
> > pretty low, 50% or less.  If you are like  most operators, you will be
> > doing more listening than transmitting.  Let's  say you transmit 30% of
> > the time.  At the risk of greatly oversimplying  things, here is the way
> > I would figure it:
> >
> > For RX:  24 hrs x 250 mA  x 70% time factor =  4.2 amps
> > For TX:  24 hrs x 2.0 amps x 50% duty cycle x 30% time factor = 7.2 amps
> >
> > The 2 amps I use for the TX current is meant to be conservative figure;
> > you  probably won't use that much at 5 watts with a well built K2.  Most
> > of the  jump-start gel cell batteries I see in the discount stores are
17
> > amp hour  ones.  That much capacity should be adequate unless you
> > transmit a lot more  than the scenario I have outlined above.
> >
> > Good luck,
> >
> > Don
> > K2 #2478
> >
> >
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>
> ----------------------------------
> David A. Belsley
> Professor of Economics
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