[Elecraft] KPA500 mobile?

[Phil Wheeler]

And then there's the car's electronics. Some 
modern ones don't react well to high power RF. I 
had one which didn't like 100 W -- though backing 
off to 50 W made all things OK.

Phil W7OX

On 4/14/17 10:27 AM, Ron D'Eau Claire wrote:
> One issue with mobile QRO is the antenna. While a mobile whip/loading coil combo can be designed for high power, it becomes difficult to prevent corona discharge from the end of the whip while transmitting at high power.
>
> One fairly common solution decades ago was to mount a copper toilet tank float on the end of the antenna. Of course the wind resistance then required guying the whip. Since it was typically on the rear of the car, a nylon cord from the mid-point to somewhere forward on the roof was common.
>
> Another approach - back when car bodies were steel - was to extend the whip to it could be bent over and tied to the front bumper, turning the car body and whip into a small loop antenna.
>
> Today, it might be hard to establish the necessary distance from the antenna while sitting in the car to meet modern RF exposure limits, especially on 20 meters and up.
>
> I never went QRO in my car, but had buddies who tinkered with it way back when vacuum tubes were "king". Back then I lived in the land of the "California Kilowatt" (Southern Calif.). They mounted outboard generators on their car engines to handle the power demand. Adding filaments, etc., a kW mobile station might require 1.5 or 2 kW of d.c. power to run it. Got a chuckle out of them when they'd key the mic to transmit while sitting at a stop light with the engine at idle, and the sudden added power demand caused the engine to stall.
>
> 73, Ron AC7AC