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Topic: DC Ground  (Read 567 times) previous topic - next topic

DC Ground

I'm replacing all kinds of stuff.  Did the house batteries, a new Rayzar Automatic over the air antenna, and am working on installing the Winegard T 4 to replace the tracvision.

Most has gone fine but I am a bit puzzled.  The ground wire on my old antenna (motorized) has 11.92 volts.  I also see no in line fuses.  I'm installing one on both antennas because pictures of these rigs in flames are troubling.

Should my DC ground have voltage?  Could I ground to the same aluminum bulkhead I'm using to ground my voltmeter? 

By the way.  Marc at Centex Batteries is a very good supplier of Lifeline Batteries. 

Re: DC Ground

Reply #1 –
A ground wire to a true coach ground should have no voltage.  Most ground wires in your coach will feed back to a common ground post and then to the coach frame.  There are a couple of these.  Grounding to a frame member in the coach body may not be reliable.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: DC Ground

Reply #2 –
Quote from: Roger & Susan in Home2 –
A ground wire to a true coach ground should have no voltage.  Most ground wires in your coach will feed back to a common ground post and then to the coach frame.  There are a couple of these.  Grounding to a frame member in the coach body may not be reliable.

Thanks Roger.  That was my gut.  Surely I can find a good ground wire in the forward bulkhead.  But, I'm done for tonight.  Whipped. 

Thank you again.

Re: DC Ground

Reply #3 –
A Winegard antenna coax should have 12 VDC between the center core and coax outer ground.  It powers the boost signal.  But the center core is the positive, the outer jacket the ground.  You may have a strand of the outer ground jacket touching the center core some place or a loose connection with the ground not making good contact.  Check connectons. Keep going "upstream" until the readings are correct.  Then either replace the bad section of coax or remedy the bad connection.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: DC Ground

Reply #4 –
A bad (or less than perfect) coax connection could be why you would see some voltage (less than normal voltage) bleeding into the shield layer of the coax.  Some resistance there might account for the voltage drop. If it were a good short you should trip a circuit breaker or fuse.  In any case this is a constant drain on your batteries.

If it is a powered antenna are there separate wires for 12 v and ground to the motor? Is this the ground wire that has the 11.92 volts?  Where is it connected?  If that wire has that voltage to a true ground then you have something cross wired or shorted out to the part that the motor ground is connectd to.  It could still be the coax cable.

Like Brett says, this needs to be figured out.  It is like a water or air leak.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: DC Ground

Reply #5 –
Quote from: Ralph –
didn't happen overnight..
Did that fitting go into a brass or copper connection? Could be what's called "dis similiar metal reaction". Also, moisture over the years could have done it, looks like an aluminum fitting, salt air can do that.
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
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Re: DC Ground

Reply #6 –
Wow.  This is going to get interesting.  As I clean up the old install stuff to trace sources and grounds, I thought I had it.  But...

Now when I put power and ground to my new Rayzar, the alarm clock in the bed room chirps rapidly.  I thought maybe Winegard (hda 200) low noise amp was acting as a filter.  Plugged it back into AC and the signal returned to the TV with no power to the Rayzar.  So, I disconnected the anetenna coax and the TV went dead.  So, that hda 200 must be backfeeding ...  So now for a clean power source.