Amp draw for a ...

[muthatrucker530]

Does anyone know off the top of there head, or have a ball park figure for the amp draw on a Cobra 150 DX? I got the thing runnen good. But its not great yet. I think I might be starving it. It needs more power Captain.

[Triple5]

Here is a way you can figure out what power requirements are for that 150DX, to figure it out use this formula:

WATTS divided by VOLTS will equal AMPS needed

or

AMPS X VOLTS = WATTS

Just a handy formula when trying to figure power requirements
an example would be:

150 watt radio and you need to figure how many amps you would need at 13.8 volts

so 150 divided by 13.8 = 10.87

so a 15 amp supply should work fine, remember you need to know what the PEAK watts are to make sure you have the highest wattage for this to work, hope this was some help

[muthatrucker530]

Thanks for the math tutorial. I mean it. I like the way you rounded up.

[Filmpros]

Math seems right...the why is it that Sam from Magnum told me my S-690 with 20 Watts Dead Carrier and 80 watts peak needs 22 amps to operate properly? My gut instinct is that he is correct....as I can't get full swing without that much amperage.

Rich

[626s]

You mean s-680. if it took 22 amps to operate that radio. then why do they put a 15 to 20 amp fuse in the power cord from the factory? i've also seen 10 amp fuse's in them. they seem to pull about 7 to 9 amps. Hope this helps. Happy Trails.

[Midlander]

Ya i agree.. Seems a bit out there for a radio to use that much.. I mean my RM Italy 150-300Watt PEP amp uses up to 23AMPS...... And that the amp...

[dud muck]

Math seems right...the why is it that Sam from Magnum told me my S-690 with 20 Watts Dead Carrier and 80 watts peak needs 22 amps to operate properly? My gut instinct is that he is correct....as I can't get full swing without that much amperage.

Rich

22amps at 13.8vdc is about 300watts DC. At 80watts RF out that would be 27% efficiency: 80/300 = 0.27

27% seems about right, i suppose.

Anyways, the earlier post about the cobra 150dx: all those radios i see sold on the web are 15watts transmit power. It seems a 15watt radio would draw at least four DC amps on transmit.

[Mountaineer]

OK I will throw in my two coppers.

You need to account for constant power or RMS. Peak power will not blow fuses because its not sustained current.

If you are figuring for amps use 75 percent of the PEP watts, that is a better indicator as to power requirements. ( Watts/Volts=Amps )

Example Cobra 19DXIV
7 watts / 13.8 volts = .5 amps

The unit I have sitting around has a 1 amp fuse in it. The manufacturer uses a fuse to stop the unit from shorting out. The actual fuse has nothing to do with how much amperage the unit is using but it does have to allow enough amps to pass without blowing.

When in doubt use the smallest fuse you can find and if it blows go to the next size, if that one blows too, then step it up to the next amperage until it quits blowing.

Also remember that regular fuses are meant to break the circuit when the amps get too great at a certain amount of TIME. If you use quick blow fuses that sucker will pop ever time you SWING BIG. Watch the type you buy!

I suggest a 10 amp slow blow.