Wouxun KG-XS20G power fuse

[Newb]

I just unwrapped the battery power code for my new XS20G and found a fuse in the negative lead.  If this fuse blows for some strange reason, won't the ground path fry to go through the antenna and roast the antenna or the finals????  If you keyed the mic, I would think it would roast the SOC!!!  Am I wrong???  

I don't think there should be a fuse in the negative lead.  It also has 2 fuses in the positive when you use the lighter power cord.  On in the line at the radio and one in the lighter plug!

I know that in order to determine if the power to the radio is on, I have keyed the mic. 

[Sshannon]

1 hour ago, Newb said:

I just unwrapped the battery power code for my new XS20G and found a fuse in the negative lead.  If this fuse blows for some strange reason, won't the ground path fry to go through the antenna and roast the antenna or the finals????  If you keyed the mic, I would think it would roast the SOC!!!  Am I wrong???  

I don't think there should be a fuse in the negative lead.  It also has 2 fuses in the positive when you use the lighter power cord.  On in the line at the radio and one in the lighter plug!

I know that in order to determine if the power to the radio is on, I have keyed the mic. 

Test it for yourself. Connect the positive lead to positive, leave the negative disconnected, and put a voltmeter between your antenna and ground. (Voltmeters are high impedance so current would be very low if there was any.)
The power supply requires connections to both positive and negative in order to work. That fuse may even provide some reverse polarity protection. 

[axorlov]

It actually makes some strange sense, although I would not wire my radio like this.

If you wire the radio (or sound) equipment directly to the battery, it makes sense to have fuses on both leads, as close to the battery terminals as practically possible. For the situation when the main ground connection from your battery to the body of the car deteriorated (rust or sloppy repair job), and now the connection between car body and the battery goes via your radio. It is now a connection for ALL consumers of electricity in your car, combined. The circuit would look like this:  the mounting hardware/bolts - body of your radio - this thin negative wire. Or maybe via NMO mount - shield of the coax - body of the radio - thin negative wire. You will have this wire melted in the result. Coax will be fine, though, shield should be good for 20A or more, if it is RG58 or RG8X. However, your finals are not in the circuit. If it is a base install, then nothing to worry about, your radio is not powered, nothing is going to happen at all.

Wouxun saved $0.0002 by omitting the fuse in the positive wire, shame on them. But the fuse only on the negative lead is better than the fuse only on the positive lead, if we are talking about car install where body of the radio connected to the body of the car by mounting hardware.

[Newb]

Well, I should have given this a little more thought before putting my fingers on the keyboard.  The SX20G has a momentary push button to initiate power on/off which fires the latch for power on.  With out a ground, there is no power on latch.

I did pull the cover off my old radio (not under warranty) and the SO239 connects to the metal chassis which is bonded to the negative trace on the motherboard with a soldier strap.  The ground/negative wire goes directly into the radio and is soldiered to the ground trace of the board.  The power (positive lead) from the filter goes through a SPST switch on the back of the volume control. 

Drug out the ol Fluke 177 and checked for a resistance path from the antenna to the negative power lead.  There is a 60M ohm path through the load coil to the ground wire on the radio.  It seems like I remember during my CB days, a guy talking about the ground for his CB corroding away on the battery of his old pickup truck and roasting a CB.

I will follow good automotive practice and remove the fuse from the ground wire and use only a fuse on the positive lead.  I do agree with the though of reverse polarity!

[axorlov]

1 hour ago, Newb said:

I will follow good automotive practice and remove the fuse from the ground wire and use only a fuse on the positive lead

Do you run the negative lead all the way to the battery or just to closest available point on a car body? If to the battery, the good automotive practice would be to have fuses on both wires. Why do you need the fuse on negative lead is explained above.

[KAF6045]

A fuse on both leads seems to be common for all the mobile radio's I have -- except those that had cigarette lighter plugs for power (and some of those are dual fused as they have one in the power lead, and one in the lighter plug). Having one on each lead doesn't hurt anything and, as explained, is pretty much a requirement when wiring direct to the battery -- since if the negative/ground cable comes loose from the chassis, the radio negative lead becomes the vehicle ground and all current will be going through the radio's lead (it probably won't damage the radio directly if the route is through the vehicle frame, the radio mounting bracket, the radio chassis, ground/negative lead, but the lead isn't sized to handle the current).

A fuse only on the negative, however, is unusual.

My recent install (Icom ID-5100A) is wired to the battery with fuses on each lead. The MXT-115 and Cobra CB [an old model where the entire radio is basically the microphone (there is a small box where the microphone, power, and antenna connect) both had lighter plugs for power (along with inline fuses). I cut the plugs off and spliced the power leads into the ID-5100A leads (which was already spliced as it too 18feet of wire to go from radio to battery, but it only came with 9feet of power-leads). Since the Icom is 50W, I doubt a 15W GMRS or 4W CB is going to strain the power leads. And the odds of having three free hands to hit PTT on all three rigs at once is pretty much 1:infinity! 

[Newb]

Just had a discussion with a buddy who is a GM Technical Assistant.  I met him when I was a mechanic.  I filled him in on our thoughts.  The first thing he asked me was, "is the radio made in China?"  I told him it was.  The answer he gave for the fuse on both leads was simple.  The rest of the world still makes some positive ground vehicles and the manufacturer doesn't want the expense of two different harnesses so they put fuse holders in both leads and they are covered.

He said "if the item you are installing isn't GM approved you are on you own if anything happens".  I said "naturally"! 

His thought was to add a terminal strip for the positive side and the negative side, don't attach ANYTHING directly to the battery.  Put a fused lead from the positive terminal of the battery to the terminal strip.  Attach a jumper from the nearest regional ground to the negative terminal strip. (un-fused)

He suggested looking at this website: https://www.w8ji.com/mobile_ground.htm