Got another radio, curious as to current draw?

[Stites]

Hi again, yall!

So I'm doing a little horse trading with the Magnum S3 that has issues, and in the process I've acquired an S380. Very solid radio, only thing holding it back I think is the coax/antennas(cophased coaxes factory installed by Kenworth, dual 4' Francis antennas), and possibly bigger power supply cable.

I say power supply cable because I'm running one from a Cobra 29 Classic, meant for a 4W output radio. I could swing 100 if I wanted, so that has to be a weak link, right? I have a Magnum noise filtering cable for it with bigger wires and a 10-amp fuse. My concern is that 10 amps might still be starving the radio, since there's always a lot more wattage going into one than being put out from it. Assuming power = voltage x current, 14.4V x 10A = 144W. For some reason that sounds a bit too low.

Would I benefit at all from running say, a 15A fuse at the truck's panel(has a dedicated CB circuit on it), and then straight-wire the filter/power cable to it? Or should I stick with 10A?

 

[westviewfire911]

Are you running this off of a closed 12v circuit or a power inverter off of a power supply?

 

[Stites]

It's in a dump truck I'm assigned to. I went ahead and left the 10A fuse block inline and haven't had any real issues yet. Of course, I leave the power level set between 0 and 1 to try and stay legal, so it doesn't draw like it would if I kept it cranked all the way. Only time I really turn it up is if errbody's yapping nonsense and I need to get something important across it all in a hurry, or if I need to reach over the hills or through the trees around here.

 

[n5ims]

A fuse will not limit the current that flows through it, it will simply blow if current above that attempts to flow (saving your truck's electrical system from damage). A 10 amp fuse will pass the same current as a 20 amp fuse, but will blow much earlier if the current exceeds the rated values. The kicker is that the wire also has an amp rating and your fuse should be below that value since you really do want the fuse to blow prior to your wire catching fire. Simply changing the fuse out for a larger value will not give you more amps, it just may make it so when you do draw more current than the wire is designed for your truck may catch fire costing thousands than the fuse blowing, costing just a few dollars.

 

[cmdrwill]

The factory wiring for CB radios is meant for a 5 watt radio. The actual wire in the factory wiring harness is too small for even most Ham radios. Not to mention the poor ground wire...

 

[Stites]

Hence the new power cord. It's actually a Magnum cord as well. I get how the fuse operates and all, it just seems like either Magnum made a super efficient radio, or I'm lousy at math.

I know it's a totally different animal, but my Peavey Ultra 112 tube amp puts out 60W of power to the speaker. But it uses 210W to do it. That's what got me wondering about the size of the fuze.

 

[KE5MC]

Unless I know otherwise I always 'assume' a radio is at best 50% efficient. Radio rated at 50w RF would need 100w of DC power. Expect the best and plan for the worst.

Mike