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[aprssig] Portable Ops from 12v via 115 VAC

Richard Amirault ramirault at erols.com
Wed Dec 29 14:57:54 UTC 2004

Third paty comment....

Bob, you don't address his main point .. that an inverter (at or near peak 
load) draws *considerable* amps from the vehicle electrical system.

And, assuming NO LOSSES (100% efficient) a 12v rig drawing 20 amps will draw 
20 amps from the vehicle   (20 amp 12vdc into the inverter, 120vac out to 
the power supply, 12vdc out to the rig) And of course it wlll be more 
because of losses.  YES, for *transfering* the power, over a long distance, 
the higher voltage is better, but his point (I think) was that a vehicle may 
not be able to sustain this drain for very long.

Now, having said that, I'm not sure how much current you will need to run 
all your equipment. This will vary, of course, from person to person but 
obviously peak power is on transmit, and you won't be transmitting all the 
time, or even most of the time (unless you were net control, or something).

Richard Amirault              N1JDU
Boston, MA, USA          Go Fly A Kite
----- Original Message ----- 
From: "Robert Bruninga"
Subject: [aprssig] Portable Ops from 12v via 115 VAC

> For long distance portable operation from the car's 12v
> system, dont overlook using lots of small wire and an
> 110 inverter.
> Run an efficient inverter at the car to 110 then run
> your portable station on  AC using modern switching
> supplies.
> Even if your 12v rig draws 20 amps peak, this should
> only be about 2 amps over the AC cord and even if the
> drop over 300 feet of zip cord goes down to 90 volts, almost
> all switching power supplies these days can still work
> and deliver their rated output at the load.
> Bob

>>>> wa7nwp at jnos.org 12/29/04 2:37:58 AM >>>

>> Bill, are you suggesting this actually WORKS?
>> I have a 300 watt inverter (500 surge), and it
>> Draws OVER 30 AMPS.  No car alternator will put
>> Out enough current to keep up with the drain at idle.
>> Are you willing to put a brick on your gas pedal and
>> Idle at 3,000 RPM to get enough current?

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