In article ,
Rick wrote:

The point of my question was, I want to fabricate a DC power cord for the
VXA-700 with a Powerpole connector on one end, and I need to know if I can
just feed 12 volts into the side of the VXA-700, or does their cigarette
lighter adapter have some kind of voltage reduction or current limiting
circuitry in there?

The Yaesu adapter which I bought for use with my VX-5 apparently
contains a surge suppressor (a varactor or zener, I suppose) and a
fuse.

I believe that the intent is to make sure that a high-voltage spike on
the car wiring (triggered by "load dump" - e.g. turning off the
headlights and thus abruptly reducing the current load on the system
when the alternator is running) doesn't reach and burn out the radio.
Automotive electronics for "12-volt" systems are normally engineered
to be able to withstand a short spike of as much as 50 volts above
ground... that's the magnitude of what you have to be concerned about.

I've fed my VX-5 power directly from a 12-volt gel cell which was not
connected to a car electrical system, and it was perfectly happy with
it. If that's all you're planning on doing, you can probably just use
the PowerPole arrangement.

If you plan to have the radio plugged into the lighter outlet when the
car is turned on, however, it'd be safer for you to provide some
voltage clamping and filtering, just as Yaesu does.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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