How many amps does a mobile cb radio draw? I have a Uniden Pro520xl. I
computer power supply has 12volt connections would it be enough to power the
radio? I have a DC plug adapter that is 14volt, 360 milliamps and a 13
volt, 800 milliamp. The 14 volt plug gives poor audio quality even from a
100 feet away and the 13 volt just blows the fuse. Any comments?

On Wed, 11 Aug 2004 16:58:36 -0700, "Chris" wrote
in CoySc.66092$sh.37930@fed1read06:

How many amps does a mobile cb radio draw? I have a Uniden Pro520xl. I
computer power supply has 12volt connections would it be enough to power the
radio? I have a DC plug adapter that is 14volt, 360 milliamps and a 13
volt, 800 milliamp. The 14 volt plug gives poor audio quality even from a
100 feet away and the 13 volt just blows the fuse. Any comments?


Few CB radios are fused for more than 3 amps (3000 milliamps) so your
power supply should be able to supply at least that much, although you
could probably get by with a 2 amp supply without much problem. The
supply should be regulated to prevent noise and/or damage to the
radio, so a wall-wart is not a good choice. A computer power supply
does have a regulated 12 volt output, but the problem here is that the
5 volt output uses a 'switching' regulator -- a type of supply that
requires a minimum load (usually about 10% of maximum) or it will burn
up -regardless- of the load on the 12 volt supply. It's also a good
idea to put capacitors across the outputs to reduce the RFI generated
by the switching power supply. Also remember that the 12 volt output
from the computer supply is a little shy of the 12.6 to 13.8 volt
requirement of the radio. In other words, after all the effort and
expense, the results are usually less than adequate. Your best bet is
to buy a power supply designed for your purpose.






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"Chris" wrote in message
news:CoySc.66092$sh.37930@fed1read06...
How many amps does a mobile cb radio draw? I have a Uniden Pro520xl. I
computer power supply has 12volt connections would it be enough to power
the
radio? I have a DC plug adapter that is 14volt, 360 milliamps and a 13
volt, 800 milliamp. The 14 volt plug gives poor audio quality even from
a
100 feet away and the 13 volt just blows the fuse. Any comments?


In computer power supplies only the 5v output is regulated. The 12 volt out
put is unregulated which means that as you draw current the voltage drops.
It's pretty low to start with (13.8 volt is the recommended voltage for
mobile radios) at 12v and you'll find that if you transmit or wind up the
volume the voltage might well drop to 11volts and the rig will not work.

The DC plug adapters arn't going to give you enough current you'll need more
than 1amp = 1000milliamp on transmit It is likely that you have got the
polarity wrong on the 13 volt adapter is swapped over i.e. you are
connecting possitive (red) to negative (black) by mistake. This will blow
the fuse.

Suitable power supplies are available from Maplin and sold as "Regulated
13.8v Power Supplies" and come in a range of max currents from 2.5 amps to
30 amps. The 2.5 amps will do at a pinch. 5amp might last longer.

Gareth
www.g1lvn.org.uk

Chris, if you have a stock radio, say between 4-10 watts of output, i'd
say you may see a MAX of 5-7 amps.
If you insist on using the cigarette/power plug get good plug in with a 10 amp
fuse.This wont blow unless
you have a serious problem. You can get them at any Radio Schack or truck stop.
Otherwise, run a fused line to your terminal/fuse block, tap a fuse holder and
be done with it. I go to the battery.
Good luck, 333
From: "Chris"
How many amps does a mobile cb radio draw? I have a Uniden Pro520xl




"Got RF?"

The Pro520xl should draw more than 3 amps. I can't guarantee that I have
one, but I'll look to see if I have a 2.5-3am PS somewhere in the dark
recesses of my fortress of solitude. IF I do, I'll let ya know, and if you
send money for shipping you can have it for free. I'll look around Monday -
no promises ( I may have thrown it out, or sold it at a long ago hamfest).
Woody.


"Chris" wrote in message
news:CoySc.66092$sh.37930@fed1read06...
How many amps does a mobile cb radio draw? I have a Uniden Pro520xl. I
computer power supply has 12volt connections would it be enough to power
the
radio? I have a DC plug adapter that is 14volt, 360 milliamps and a 13
volt, 800 milliamp. The 14 volt plug gives poor audio quality even from
a
100 feet away and the 13 volt just blows the fuse. Any comments?