RV installation - Cobra 18 WX ST II

[Shutterbug57]

I have a Cobra 18 WX ST II that I want to install in my motorhome. I plan to use this in CB mode while running down the road and primarily in WX mode while stationary. I don’t want to have to find to the RV key and turn it to accessory just to check a WX report.

This radio has a black (ground), red (hot) and orange (hot) wire. The instructions indicate the red should go to a switched source while the orange goes to a constant source. I am not sure what user settings the orange wire is saving, but I simply want to be able to use the on/off knob in the radio to power it on and off as the RV will be powered by shore power most of the time it is not on the move.

In hooking this up, which of the following should I do:

1) ignore the orange wire and go red to constant power

2) ignore the red wire and go orange to constant power

3) pair up the red and orange wires and connect both to constant power

4) something else

I appreciate your input.

[Bozo]

[mention]Shutterbug57[/mention]
I would go to battery directly, but you can also connect to fuse box... I wouldn't use cigarette lighter adapter because of noise in constant power consumption.

• Connect the red lead of DC power cord to an
  accessory 12 volt fuse.
• Connect the orange lead to a constant 12v fuse
  (ie: cigarette lighter or direct to battery)
• Connect the black lead to the negative side of
  the automobile.This is usually the chassis. Any
  convenient location with good electrical contact
  (remove paint) may be used.

Screenshot_20210106-053310_Drive.jpg

Download-Link

Cobra 18WXST II Owners manual and installation guide

[Shutterbug57]

• Connect the red lead of DC power cord to an
  accessory 12 volt fuse.
• Connect the orange lead to a constant 12v fuse
  (ie: cigarette lighter or direct to battery)
• Connect the black lead to the negative side of
  the automobile.This is usually the chassis. Any
  convenient location with good electrical contact
  (remove paint) may be used.

Screenshot_20210106-053310_Drive.jpg

Yeah, I read the book. That set up requires that you turn the vehicle key to the accessory setting. That is what I am trying not to have to do. Further back, it indicates that for temporary set up you can put both orange and red to one side of a cigar plug and black to the other. That is an option, but I am using Anderson Power Poles to connect, so would like to not have 2 wires going into the red connector. I could join the red and orange to a single red, then crimp it into the red connector or, if I can ignore one of the wires, eliminate a splice (potential failure point) and just connect one wire to the red power pole connector.

[Bozo]

LoL. I updated my first post. I thought you might ask that...

[mention]Shutterbug57[/mention]
I would go to battery directly, but you can also connect to fuse box... I wouldn't use cigarette lighter adapter because of noise in constant power consumption.

[Shutterbug57]

LoL. I updated my first post. I thought you might ask that...

@Shutterbug57
I would go to battery directly, but you can also connect to fuse box... I wouldn't use cigarette lighter adapter because of noise in constant power consumption.

I understand that approach, but the battery and fuse box are 35"+ away from the dashboard in my motorhome. I have no intention of running wires through the storage bays to get to the battery box or fuse box. The prior owner had a radio installed and the red and black wires are already at the driver's area by the coax. I plan to use those and I have terminated them with Anderson Power Pole connectors. If I have to put in a choke to get rid of interference, that is not a problem.

[Bozo]

I understand that approach, but the battery and fuse box are 35"+ away from the dashboard in my motorhome.

Only 35 inches? That is not very far... jk

Yep, if you get a lot of noise...You can just use a Ferrite

[MDYoungblood]

I've never had one or even read the instructions but connecting to a fuse box usually will be noisy because it has fan motors and wiper motor connected to it, best to run right to the battery and with it being an RV, there should be an auxiliary battery or power converter with a good 12v source. Hooking to the auxiliary battery will keep from draining the starting battery on the RV.

3's

Greg

[Kalkavekkian]

Run the orange to the battery red to acc black to good ground. 35 inches is closer than most cars or trucks i have wired radios to and there are almost always places with a rubber grommet or existing hole in firewall to go thru. I use a bit of silicone to seal up even better when finished. A good heavy duty rv battery will fun an 18 quite awhile with no worries.

[Shutterbug57]

Run the orange to the battery red to acc black to good ground. 35 inches is closer than most cars or trucks i have wired radios to and there are almost always places with a rubber grommet or existing hole in firewall to go thru. I use a bit of silicone to seal up even better when finished. A good heavy duty rv battery will fun an 18 quite awhile with no worries.

35” should be 35’. It’s a typo that I could not edit. There are good reasons in an RV to NOT go direct to the battery. You want all connections after the battery disconnect so that you don’t kill the batteries with parasitic drain while it is stored.

[Kalkavekkian]

Yup that is a long way. Maybe if you have a place to stash it use a small auxiliary battery such as a mower or motorcycle battery fastened down well out of sight.

[MDYoungblood]

Run the orange to the battery red to acc black to good ground. 35 inches is closer than most cars or trucks i have wired radios to and there are almost always places with a rubber grommet or existing hole in firewall to go thru. I use a bit of silicone to seal up even better when finished. A good heavy duty rv battery will fun an 18 quite awhile with no worries.

35” should be 35’. It’s a typo that I could not edit. There are good reasons in an RV to NOT go direct to the battery. You want all connections after the battery disconnect so that you don’t kill the batteries with parasitic drain while it is stored.

That is the reason I suggested connecting it to the auxiliary battery system, they are disconnected from the RV's starting battery when the key is off plus they are charged by the voltage converter when plugged in. If you are worried about draining the batteries during storage then you should have a "master disconnect switch" to shut down all the system or get a solar charger to keep the batteries topped off.

3's

Greg