[Elecraft] K3 going expeditionary

[Rick NK7I]

Not only is the accessory circuit shared with others, it is often loaded 
with noises from the electronics in the vehicle.  They can harm both 
your RX and TX signals.

It takes a little time to run #12 ROMEX (with 40 or 50 A mobile, 
self-resetting circuit breakers at the battery to protect the wire, 
fuses for radios AT the radios; both positive and negative) but the 
returns are worth it.  You'll have to remember to turn the K3 OFF each 
time you start the engine; the wandering voltage could cause harm or 
scramble the settings.  Also bond to chassis AT the K3 to keep some RFI 
down...

*IF* you have a newer vehicle that measures current draw and charging 
rate at the battery (sometimes via the negative pole), you'll want to 
use that sensor point for negative connection; not at the battery.

That's the super quick description, to start a foundation of proper set up.

73,
Rick NK7I


On 8/23/2020 11:32 AM, Ed K1EP wrote:
> You could do that. I wouldn't advise it for other reasons. Why don't you
> measure the current at different power levels when on a power supply? There
> is a current display on the radio. The cigarette plug is not directly
> connected to the battery. There is likely to be poor connections resulting
> in IR losses and other problems.
>
> On Sun, Aug 23, 2020, 14:22 Ted Edwards W3TB <w3tb.ted at gmail.com> wrote:
>
>> I am planning to put my K3 in the car for the upcoming Tennessee QSO Party
>> so that I can go rover/expeditionary.
>>
>> With that comes a question:  Powering from that accessory socket which
>> appears limited to 15 amps instead of the 20 amps that the K3 wants at full
>> power, do I understand right that reducing to 50 watts output and taking
>> the -3dB will work out in terms of power draw?
>>
>> In the past, I have done QRP and would like to be a bit louder this time.
>> Thanks to all who might respond.
>>
>> --
>> 73 de Ted Edwards, W3TB and GØPWW
>>
>> and thinking about operating CW:
>> "Do today what others won't,
>> so you can do tomorrow what others can't."
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