Pickup cab grounding

[Groundhog1960]

Has anyone here grounded the cab of your pickup truck without removing the
headliner and, if you did, how did you do it for best results?
Thanks in advance.

 

[prcguy]

Grounded the cab to what? I've bonded the cab of my truck to the bed using two wide braid straps at the top of the bed rail behind the cab to the cab near the outer edges of the cab to make more of a continuous ground plane. This was on a late 2000 Tundra. Why would you have to remove the headliner to ground the cab?

 

[Groundhog1960]

Grounded the cab to what? I've bonded the cab of my truck to the bed using two wide braid straps at the top of the bed rail behind the cab to the cab near the outer edges of the cab to make more of a continuous ground plane. This was on a late 2000 Tundra. Why would you have to remove the headliner to ground the cab?

Thanks. To the frame or bed either one. I forgot that. Just trying to make a better ground for my triple mag mount to sit on on top of the cab. Appreciate the info

 

[Groundhog1960]

Grounded the cab to what? I've bonded the cab of my truck to the bed using two wide braid straps at the top of the bed rail behind the cab to the cab near the outer edges of the cab to make more of a continuous ground plane. This was on a late 2000 Tundra. Why would you have to remove the headliner to ground the cab?

You don't I suppose. I just read another thread where someone took down their headliner to run a ground from it to the frame, or whatever he was grounding to.

 

[mmckenna]

You don't I suppose. I just read another thread where someone took down their headliner to run a ground from it to the frame, or whatever he was grounding to.

DC grounds and RF grounds can be different things. Long grounding leads won't necessarily help. PRCGUY and the strap bonding between the cab and bed makes more sense.

If you are really concerned about grounding/bonding, look at the benefits of doing a permanent install. Magnetic mounts are certainly easy, but they are not necessarily the best solution.

 

[Groundhog1960]

DC grounds and RF grounds can be different things. Long grounding leads won't necessarily help. PRCGUY and the strap bonding between the cab and bed makes more sense.

If you are really concerned about grounding/bonding, look at the benefits of doing a permanent install. Magnetic mounts are certainly easy, but they are not necessarily the best solution.

Thanks. I appreciate it.

 

[prcguy]

Ideally your antenna wants to see a giant infinite size flat metal sheet under it. Second best would be a continuous sheet metal disc that goes out 1/4 wavelength in all directions from the antenna base. There will be RF currents flowing on the metal sheet from the base of the antenna out to the edges then back towards the antenna. Any discontinuities in the metal sheet break up the RF currents and reduce the effectiveness of the ground plane.

When you put a CB antenna on the roof of a truck the ground plane is way too small, it usually works ok but it would work better if the truck roof was 18ft in diameter, which is not practical. To increase the ground plane you can sometimes bond the cab to the upper bed wall with wide flat conductors and that will allow some RF currents to flow down the cab to the bed wall then around the walls and floor of the truck bed extending the ground plane some. To do this right the flat conductors need to start on the cab slightly above the bed rail and make a smooth bend down to the bed rail. If the conductors are between the bed rail and cab way down below the top of the bed rail then RF currents will not make a good transition and you will only have a DC connection and not an RF connection between different parts of the truck.

This also means a wire from the base of the antenna to the frame is not part of a "ground plane" and a wire on the inside roof of the cab to the frame or battery or whatever will never be seen by the antenna because no or very little RF currents will be flowing on the inside roof of the cab. That wire is a DC connection and not an RF connection.

You kind of have to look at it like water flowing out of the base of the antenna across the roof and down the cab. If the water doesn't easily flow to another part of the vehicle with a large flat horizontal surface via a connection you have made, then that connection will not work for extending your ground plane.

QUOTE="Groundhog1960, post: 3722144, member: 1309831"]
You don't I suppose. I just read another thread where someone took down their headliner to run a ground from it to the frame, or whatever he was grounding to.
[/QUOTE]

 

[Groundhog1960]

Ideally your antenna wants to see a giant infinite size flat metal sheet under it. Second best would be a continuous sheet metal disc that goes out 1/4 wavelength in all directions from the antenna base. There will be RF currents flowing on the metal sheet from the base of the antenna out to the edges then back towards the antenna. Any discontinuities in the metal sheet break up the RF currents and reduce the effectiveness of the ground plane.

When you put a CB antenna on the roof of a truck the ground plane is way too small, it usually works ok but it would work better if the truck roof was 18ft in diameter, which is not practical. To increase the ground plane you can sometimes bond the cab to the upper bed wall with wide flat conductors and that will allow some RF currents to flow down the cab to the bed wall then around the walls and floor of the truck bed extending the ground plane some. To do this right the flat conductors need to start on the cab slightly above the bed rail and make a smooth bend down to the bed rail. If the conductors are between the bed rail and cab way down below the top of the bed rail then RF currents will not make a good transition and you will only have a DC connection and not an RF connection between different parts of the truck.

This also means a wire from the base of the antenna to the frame is not part of a "ground plane" and a wire on the inside roof of the cab to the frame or battery or whatever will never be seen by the antenna because no or very little RF currents will be flowing on the inside roof of the cab. That wire is a DC connection and not an RF connection.

You kind of have to look at it like water flowing out of the base of the antenna across the roof and down the cab. If the water doesn't easily flow to another part of the vehicle with a large flat horizontal surface via a connection you have made, then that connection will not work for extending your ground plane.

QUOTE="Groundhog1960, post: 3722144, member: 1309831"]
You don't I suppose. I just read another thread where someone took down their headliner to run a ground from it to the frame, or whatever he was grounding to.

[/QUOTE]
Thanks for the response and explanation. Great answer.

 

[slowmover]

(“Water-sheeting flow description really great, @prcguy)

A great thread on this forum re noise-chasing (thanks to all on that one):

Engine RPM noise on CB radio


My temp mag mount setup with a quarter-wave to use as mock-up while power & coax is being roughed-in this week.

First two air checks have been 7+ miles (potentially higher, but not lower); first with 9’, second from better location with 4.5’. (U-885 & KL203 with KES-5).

Almost all the noise is on the coax shield (not center conductor). The rest on temporary power.

The Mobile Guide has been my go-to:

https://www.k0bg.com/bonding.html

https://www.k0bg.com/rfi.html

https://www.k0bg.com/common.html

RF Bonds & DC Grounds made in advance.


D

Horizontal surfaces have preference over vertical with openings done. Etc.

Wide & Flat for some more

 

[slowmover]

@prcguy

Am not seeing woven braid wider than 2.25” in an initial search at DXE & rf parts

The movement between cab and bed would seem to rule out using strap/sheet (3”, but sheet to 12”).

(A couple of years back I was carrying refined copper to some of the manufacturers.)

Thoughts?

 

[Groundhog1960]

Am not seeing woven braid wider than 2.25” in an initial search

The movement between cab and bed would seem to rule out using strap (3”, but sheet to 12”).

Thoughts?

I have some new 5/8 in braided ground cable. I may run 2 between the cab and bed top, like the guy above told me he did.
Thanks everyone for all the info. Very much appreciated.

 

[slowmover]

Grounding Concepts - IW5EDI Simone - Ham-Radio

 

[prcguy]

Most of the grounding I do or have done on my vehicles is to improve lower HF bands like 80m and 40m where the entire vehicle is a tiny fraction of what is needed for a ground plane. Bonding the cab to the truck bed or hood to surrounding body parts is good for that but may not do anything noticeable for a roof mounted CB antenna. Before committing to drilling holes and installing an exposed chunk of braid, its nice to test a temporary version to see if it will actually do anything. "Shot gunning" in fixes without a specific need can waste a lot of time and $$ with no benefit. If you have a problem and do too many things at the same time, you will never know what actually fixed a problem. Test first then do what works and don't just pile on unproven cures.

Another thing bonding body parts can do at any HF frequency is reduce ignition noise from getting to the antenna. If your spark plug wires are radiating lots of interference then bonding the hood can help with that. Same with the exhaust system, the spark plug wires run all around exhaust headers which can be excited with RF from the plug wires and the entire length of the exhaust pipe can be an antenna that radiates the interference. Bonding the exhaust pipe to the frame or body right where it exits the engine compartment then again near the tail pipe can reduce the radiation and pickup by your antenna.

I have some new 5/8 in braided ground cable. I may run 2 between the cab and bed top, like the guy above told me he did.
Thanks everyone for all the info. Very much appreciated.

 

[Groundhog1960]

Most of the grounding I do or have done on my vehicles is to improve lower HF bands like 80m and 40m where the entire vehicle is a tiny fraction of what is needed for a ground plane. Bonding the cab to the truck bed or hood to surrounding body parts is good for that but may not do anything noticeable for a roof mounted CB antenna. Before committing to drilling holes and installing an exposed chunk of braid, its nice to test a temporary version to see if it will actually do anything. "Shot gunning" in fixes without a specific need can waste a lot of time and $$ with no benefit. If you have a problem and do too many things at the same time, you will never know what actually fixed a problem. Test first then do what works and don't just pile on unproven cures.

Another thing bonding body parts can do at any HF frequency is reduce ignition noise from getting to the antenna. If your spark plug wires are radiating lots of interference then bonding the hood can help with that. Same with the exhaust system, the spark plug wires run all around exhaust headers which can be excited with RF from the plug wires and the entire length of the exhaust pipe can be an antenna that radiates the interference. Bonding the exhaust pipe to the frame or body right where it exits the engine compartment then again near the tail pipe can reduce the radiation and pickup by your antenna.

Thanks. All info appreciated. I have already ran a ground cable from the negative battery post to the alternator bracket and believe it or not, it helped considerably.

 

[prcguy]

This helped with reducing ignition noise and not SWR or range, right? For noise it might be better to ground the alternator to the closest sheet metal body part rather than back to the battery.

Thanks. All info appreciated. I have already ran a ground cable from the negative battery post to the alternator bracket and believe it or not, it helped considerably.

 

[slowmover]

This helped with reducing ignition noise and not SWR or range, right? For noise it might be better to ground the alternator to the closest sheet metal body part rather than back to the battery.

Added this bond today. We’ll see.

.

 

[Groundhog1960]

This helped with reducing ignition noise and not SWR or range, right? For noise it might be better to ground the alternator to the closest sheet metal body part rather than back to the battery.

Exactly. Ignition noise and the whining I was getting from the alternator itself.