Off the Grid

[Bill Levy]

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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[Paul Grigorieff-2]

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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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[Lynn W. Taylor, WB6UUT]

If I'm reading this correctly, on receive, you're drawing 240 to 280 watts.

At 12 watts, you're drawing 360 to 420 watts.

For 50 watts out, you need more than 800 watts in.

Someone else suggested that a 60 amp-hour car battery would probably run
the rig for a day.  If I'm reading this correctly, you'd do no more than
3 hours if you did not transmit.

For lead-acid batteries, you don't want to exceed the 10 hour rate, so
the smallest acceptable battery would be over 200 amp-hours, and only
for just-receive.

Something seems a little off.

-- Lynn

On 3/4/2014 2:41 PM, Paul Grigorieff wrote:
> 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.

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[k6dgw]

On 3/4/2014 2:41 PM, Paul Grigorieff wrote:
> This might be helpful.

> 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.

Hmmmm ... I power my K3, P3, and KAT500 with a Yaesu 1030A power supply.
  The KPA500 is plugged into the wall of course so I turned it off.  At
100W the total current is 21A for a total efficiency of ~40%.  I get
closer to 50% out of my K2 @ 5W output.  The K3/P3/KAT500 combo drain
might be 1A in receive, the scale is really cramped that low.  80A at
12V is 960W for an overall efficiency of ~11%.  That seems awful low to me.

A friend gave me a solar panel with a 12Ah SLAB in it.  I've only had
the chance to use it with my K2 in one Spartan Sprint [too cold out on
the deck], but I may do QRPTTF with it at the end of April if I don't do
a SOTA Summit.  The sun is headed back north but the sun angle is still
not normal to the panel and looking at the charging current vs the
average drain when I'm keying the K2 on CW @ 5W, it appears I could send
all of War and Peace during the day and not drain the battery. :-)

When I'm on the solar panel, I'm essentially "off-the-grid," all the
energy in the battery is solar.  All the rest of the time, we are
definitely *on* the grid.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2014 Cal QSO Party 4-5 Oct 2014
- www.cqp.org


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