[Elecraft] Off the Grid

[Paul Grigorieff]

This might be helpful.

I operate out of a parked RV, mostly using a 30A AC main power cable 
(so-called "shore power").  As a result of a nasty 220v surge (details 
below), I needed to buy a whole-line surge protector, which just happens 
to have a continuous, cycling display of line voltage, frequency, and 
amperage.  So I ran a few measurements to see how much power I drew at 
120v AC, translating my measurements into DC amps at 12v.

My K3, on receive, with the KAT500 in-line, the P3, and my massive 70A 
Astron p.s. powering the K3, drew about 20A DC.  Putting the K3 in 
transmit mode, with just under 12W drive (so as not to kick in the 100w 
amp) required about 30A DC.  Boosting the output to 50W drew about 70A 
DC.  Running it "wide open," at 100W out, required about 80A DC.  And 
finally, turning on the KPA-500, with 15W drive to yield 300W out, 
required 150A DC.

These readings might be useful if you're trying to calculate running 
times for your equipment using batteries instead of line (mains) power.  
If you operate on deep-cycle batteries, I don't believe you should 
consider discharging your batteries below 50% of their rated amp-hour 
capacities.

Now back to the 220v surge.  This was apparently caused by faulty 
components in the sub-main service panel serving my RV line.  The surge 
protector I bought is a Progressive Industries PT30C, $248 from 
Amazon.com.  It seems very ruggedly built and is supposed to be 
waterproof (it's outdoors), although I cover it with a plastic box as a 
precaution.

While its price may seem steep, I wish I had bought it before the surge, 
which blew out two pricey surge strips, my 12v converter/charger and 
distribution panel, and my (direct wired) microwave oven (the surge 
fried its control electronics).  This is a warning for other operators 
running from "shore power" as I was.  The situation is supposed to be 
even worse for those using campground RV hookups.
    -Paul, N1HEL
_______________________________

recently had to buy a On 3/4/2014 10:48 AM, William Levy wrote:
> The K3 runs on a car battery and an ordinary 60 amp car battery will run it
> for easily 24 hours without anything going amiss.
> I lived in Africa in the 70's and I never ran down the car's battery or the
> one in camp by operating my radios which in those days were Atlas and
> TenTec 2's.  In the 80's I ran a 500 watt Metrum Solid State 500M amp and
> it had it's own battery and I would use it for hours keeping skeds from 5Z
> and 5H to W2.
>
> I had a generator in camp and would trickle the batteries whenever we ran
> the generator which was long enough in the day to keep the fridges cold.
>
> The batteries are the least of your problems as are the radios.
>
> If you are using battery chargers the automotive trickle chargers are more
> than adequate. Nobody operates off grid for hours and hours anyway.
> Whatever you have around to charge a car/truck battery when you
> inadvertantly leave the car on all night will work just fine too.
>
> Only the guys that use solar cells have to worry about overcharging
> batteries. None of us have to worry about car/truck/marine batteries
> running down in 24 hours and I believe frankly you could run a contest
> weekend with one too but have never done it. I have never worried about
> whether my voltages were 13.8 or 12. Nothing ever got below that for me and
> I used to ham for hours and hours when younger.
>
> Your off the grid antenna should be of more concern. I like long wires.
> Longer the better.
>
> 73, Bill N2WL
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