Rockie Question - 14 Volt with 28 Volt System

Ventucky Red

Ventucky Red

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Jon
Have an opportunity to get a refurbished KX-155 for free to replace the one I have that is toast. But it is a 14-volt and I have a 28-volt system, Can a radio that is designed for 14 volts work in a 28 volt system?

I ask as I don't want to take it if it won't work.

Thanks
 
You'll need a step-down converter. Spruce sell them.
 
I assume it does not work for complex devices like a radio, but for more simple devices such as gauges, a resistor in series can step down the voltage. Installation instructions will specify the resistor.
 
While the step-down box is a solution, they are kinda pricey for what they do and it's just another device you have to attach somewhere behind the panel.

For what it's worth, the 14v models command much higher prices on the used market over comparable 28v models (just because of supply), so you could probably find a shop that would trade you straight across for the 28v version.

C.
 
camorton said:
While the step-down box is a solution, they are kinda pricey for what they do and it's just another device you have to attach somewhere behind the panel.

For what it's worth, the 14v models command much higher prices on the used market over comparable 28v models (just because of supply), so you could probably find a shop that would trade you straight across for the 28v version.

C.
Click to expand...

Yea... step down box is a non-starter. Also thought about getting and selling/swapping it, but that's not good karma.
 
If you need a certified 24v to 12v converter, it's probably going to be expensive. If you're flying experimental or can use a non-certified converter, they are available in the 20A range for probably $50 or less from amazon.

A dropping resistor could work for a constant current load, but not a transmitter. The current on transmit is going to be at least 2x the receive current, which would double the voltage drop, which means the radio wouldn't get enough voltage or current to transmit.
 
Albany Tom said:
If you're flying experimental or can use a non-certified converter, they are available in the 20A range for probably $50 or less from amazon.
Click to expand...
FYI: can use an off-the-shelf converter on TC aircraft as well. No need for a TSO unit in most cases with several legit routes to take for installation. That said, I wouldn't use a $10 Banggood unit in this case, same as using a cheap USB converter in aircraft.
 
You need a solid state voltage regulator for 14 volts dc that can handle a minimum load of about 10 amps. A dropping resistor theoretically only works properly if the current draw is constant. The radio draws very little current in receive, on transmit several amps.
 
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