Prestas' CB install + Liftgate mount + 3' firestick (pic heavy)

[Presta24]

Finally got an afternoon to run the coax and hook up the antenna. Still need to run power and mount CB. Where are you guys taping into your power at? I went with a comet RS720 mount, HD spring shock, and a 3' firestick. I also bought all of my stuff on line, I suggest going to your local truck stop! I needed a adapter, radio shack didnt have it so I went to the flying J. They had everything I had bought for what I paid if not cheaper, and minus shipping. They had 4' firesticks, 2 for $30. Pics are a little dark, it was raining and Im not real familiar with the wifes SLR.

First thing I did was pop off the kick plate in the cargo area

Next I took out the screws and clips for the luggage net shown in red, sorry my skills arent that great

Then u can pull the rear quarter trim panel away from the body.
Then I went around to the rear driver door and un bolted the seat belt, took the sill plate off and pulled the remainder of the panel away from the body. I only pulled it enough to un snap and get my hand or a screw driver in the gap.

 

[Presta24]

I hooked the coax to the antenna and taped it along the liftgate to see where I wanted it and to know how much cable I had to get up front.

There is already a harness that goes into the body at the top of the liftgate. I ran the cable in through the hole that was already there. I will have to modify the seal that goes around it. But to be honest that gromet never stays in place any ways so i think it will be fine until I can fix it.

I was able to pull the roof liner down a bit with my finger

slid the cable in and pushed it down towards the d pillar.

At this point i popped off the side pillar mirror to allow me to each up into the head liner to grab the coax, I couldn't get it pushed down into the pillar w/o doing this.

Had to remove a lil trim piece to get at a bolt I had to remove to get the top quarter trim panel farther off the body to get the cable down along side the rear window

then I ran it along side the rear quarter up to the sill plate on the rear drivers door

from here I tucked it under the sill plate, under the bottom of the B pillar trim panel, then brought it out and under the drivers seat to the center console. I didn't go under the carpet because I didn't want to cut the carpet or get into
taking apart the center console. If any one has any easy ways to get it from the B pillar to the center console under the carpet I'm all ears.

the location I want to mount the CB

?

I still have the coax taped to the inside of the liftgate, and one have suggestions for a way to keep that in place


Few random pics of the process

Taking pictures made me thirsty

 

[Presta24]

Got it wired up and mounted this am

This was by far the easy part. Went to auto zone and picked up a fuse tap, wire ends, and some velcro.

Put the velcro on the back side of the cb and stuck er on

Then ran the hot and ground up under the trim panel for the center dash. Put one of the loops on the ground wire ans attached it to a bolt on the fire wall

I took power from my ACC. So I can use the CB w/o the truck running. Took the acc fuse out, put it and another in the "add a circuit" and attached the end of the wire to the hot wire with included in line connector.

The last thing I did was hook up the mic and velcro it to the dash just below the 4H/4L knob.

I also found a cheap way to keep my cable in check on the liftgate! A few cable hanger things from office depot with sticky tape on the back side, need to get a few more though

 

[got556]

This is exactly what I needed to see. Thank you!

 

[kai920]

Presta,
Nice write up. Exactly what I am looking to do with mine. Do you know what kind of range you are getting with this antenna set up? Thx.

 

[Presta24]

I haven't had the chance to use it yet. Tried to tune it myself but didn't have any luck. Just haven't found Amy one to help me tune it yet.

 

[kai920]

Bummer, all that work and you haven't got to use it yet?

How did you ground the antenna?
What length coax cable did you use? Was it too much?

Thx again!

 

[Presta24]

I bought a 18' coax. It was perfect length. check the pics for where its grounded. I was supposed to go on a run last june but it didnt work out. I have used it a few times on the hwy when stuck in bumper to bumper to see where the truckers were going around it. Its just not clear and I dont think the rage in very far with out proper tuning

 

[kai920]

I bought a 18' coax. It was perfect length. check the pics for where its grounded. I was supposed to go on a run last june but it didnt work out. I have used it a few times on the hwy when stuck in bumper to bumper to see where the truckers were going around it. Its just not clear and I dont think the rage in very far with out proper tuning

I see where you grounded the negative wire of the power cable, but I was referring to the antenna. Don't you need to ground the antenna? Possibly, thats part of your issue? I don't knave experience doing this, but I really think the antenna is supposed to be grounded unless you have a type that doesn't have to be, and I don't think the firestik is of that type.

 

[Shimajilosan]

Antenna Placement

On an antenna, "ground" more often refers to "radio frequency" (rf) ground rather than an electrical ground. Still, the solution is a solid connection between the body, the mount (in this case a Comet RS720 locking tri-plane), and antenna receiver (a Firestick uses standard 3/8 x 24). As long as you have good contact all around, you don't need any further "grounding" on the antenna, unless you want to add counterpoise which IMHO is largely a waste for a CB.

I have used a similar Comet mount (RS840) for an amateur hf screwdriver antenna, but had it mounted further up on the door to get more antenna above the truck, rather than having the length of the antenna beside the door, thus radiating rf into the body. This could potentially provide a SWR problem, but with a CB at 4 watts AM/12 watts PEP SSB, you may get by without a significant SWR problem. I think you would have a better rf ground if you have more antenna in the clear.

I moved that mount because I got tired of the antenna always moving with the rear door when I opened it. I also had a crimping problem where the coax slips into the side of the RS840 and into the compartment. If the coax does not hit that slot right, it crimps. Finally, the mount's "teeth" did not secure at a point where the antenna was in proper position 90 deg to the roof...it locked with the antenna leaning a little forward or a little aft. I'm now mounting the antenna on top and just forward of the rear door, with the mount secured in the jamb.

Anyway, thanks for sharing your install...great job!! :hatsoff:

 

[kai920]

On an antenna, "ground" more often refers to "radio frequency" (rf) ground rather than an electrical ground. Still, the solution is a solid connection between the body, the mount (in this case a Comet RS720 locking tri-plane), and antenna receiver (a Firestick uses standard 3/8 x 24). As long as you have good contact all around, you don't need any further "grounding" on the antenna, unless you want to add counterpoise which IMHO is largely a waste for a CB.

I have used a similar Comet mount (RS840) for an amateur hf screwdriver antenna, but had it mounted further up on the door to get more antenna above the truck, rather than having the length of the antenna beside the door, thus radiating rf into the body. This could potentially provide a SWR problem, but with a CB at 4 watts AM/12 watts PEP SSB, you may get by without a significant SWR problem. I think you would have a better rf ground if you have more antenna in the clear.

I moved that mount because I got tired of the antenna always moving with the rear door when I opened it. I also had a crimping problem where the coax slips into the side of the RS840 and into the compartment. If the coax does not hit that slot right, it crimps. Finally, the mount's "teeth" did not secure at a point where the antenna was in proper position 90 deg to the roof...it locked with the antenna leaning a little forward or a little aft. I'm now mounting the antenna on top and just forward of the rear door, with the mount secured in the jamb.

Anyway, thanks for sharing your install...great job!! :hatsoff:

I'm not sure about the RS840 but the 720 is powder coated, there is no continuity between two parts of the mount. So no matter where I mount it, there is no ground. ???? Or am I still thinking electrical ground?

Mounting it somewhere higher makes more sense to me, but I still don't understand the grounding business. If the mount is actually making a connection with the vehicle, as you said if t is making good contact all around then you don't need anything. Is the RS840 not painted or powder coated or do you have a grousing wire?

 

[Shimajilosan]

I'm not sure about the RS840 but the 720 is powder coated, there is no continuity between two parts of the mount. So no matter where I mount it, there is no ground. ???? Or am I still thinking electrical ground?

Mounting it somewhere higher makes more sense to me, but I still don't understand the grounding business. If the mount is actually making a connection with the vehicle, as you said if t is making good contact all around then you don't need anything. Is the RS840 not painted or powder coated or do you have a grousing wire?

Hi...You made me look! I pulled out the multimeter and indeed there is continuity between the point where the barrel of the SO239 contacts the RS840 mount and the hex screws that secure the underside of the lip mount to the vehicle.

Here's an article that presents the basics of rf and ground relative to CB installation : Mobile Radio Installation

...and one that is a little more technical: Grounding :: Any/All

Net-net, with a CB a modicum of good technical practice in the antenna installation and proper adjustment of the SWR should be just fine. In ham radio where you are operating at 100 watts or more on much lower frequencies, proper installation and defeating ground loops are much more of a concern.

I have not used additional grounding on the RS840, but have on a screwdriver antenna that was mounted on the rear lamp guards. I have ditched the RS840 because I want to get the antenna off the door, and I'm - as soon as I go back out with an adult beverage - mounting the antenna above the rear door with an L bracket.

Cheers!!

:beer:

 

[kai920]

Hi...You made me look! I pulled out the multimeter and indeed there is continuity between the point where the barrel of the SO239 contacts the RS840 mount and the hex screws that secure the underside of the lip mount to the vehicle.

Here's an article that presents the basics of rf and ground relative to CB installation : Mobile Radio Installation

...and one that is a little more technical: Grounding :: Any/All

Net-net, with a CB a modicum of good technical practice in the antenna installation and proper adjustment of the SWR should be just fine. In ham radio where you are operating at 100 watts or more on much lower frequencies, proper installation and defeating ground loops are much more of a concern.

I have not used additional grounding on the RS840, but have on a screwdriver antenna that was mounted on the rear lamp guards. I have ditched the RS840 because I want to get the antenna off the door, and I'm - as soon as I go back out with an adult beverage - mounting the antenna above the rear door with an L bracket.

Cheers!!

:beer:

Does your mount come in contact with your chassis? Even if I removed some powered coating and confirmed continuity between the connector and the mount, the mount itself does not contact any metal, only paint, it comes with insulating material to protect the paint on the car.

So there is still no ground to vehicle chassis on the RS-720 unless a grounding wire is put on.

So with the RS 720 we should be using a NGP antenna????

 

[Presta24]

Does your mount come in contact with your chassis? Even if I removed some powered coating and confirmed continuity between the connector and the mount, the mount itself does not contact any metal, only paint, it comes with insulating material to protect the paint on the car.

So there is still no ground to vehicle chassis on the RS-720 unless a grounding wire is put on.

So with the RS 720 we should be using a NGP antenna????

I bought a neoprene bushing that slides inside the comet mount to allow the threaded end of the antenna to attach through the mount and onto the coax with out touching any metal. It might have even came with the mount, I cant remember. So if i am correct, if your antenna doesn't contact the mount, it should have a good ground through the coax, correct??

 

[Shimajilosan]

Does your mount come in contact with your chassis? Even if I removed some powered coating and confirmed continuity between the connector and the mount, the mount itself does not contact any metal, only paint, it comes with insulating material to protect the paint on the car.

So there is still no ground to vehicle chassis on the RS-720 unless a grounding wire is put on.

So with the RS 720 we should be using a NGP antenna????

NGP antennas are used when there is NO metal in sight, such as on a fiberglass or fabric shell, a balloon, or glider. As long as you have the mount connected to metal - even though you don't have electrical mount-to-chassis continuity, it should be sufficient to provide "rf ground" for the antenna, particularly for CB frequencies and power. The Firestik should work fine (provided it is tuned properly).

Remember, there are a plethora of magnetic mount antennas like the K40's and Wilson line that work great on CB freqs, and hams often used magnetic mounts for 2m (140 mhz) and 70cm (440 mhz) installations. CB (27/28 mhz) is 11m...moving below that into the ham bands, such as 20m (14 mhz) and 40m (7 mhz), providing sufficient rf groundplane becomes much more important (because the wavelength is so much larger), while combating the potential for ground loops.

:cheers:

 

[Shimajilosan]

I bought a neoprene bushing that slides inside the comet mount to allow the threaded end of the antenna to attach through the mount and onto the coax with out touching any metal. It might have even came with the mount, I cant remember. So if i am correct, if your antenna doesn't contact the mount, it should have a good ground through the coax, correct??

Yeah, but doesn't the SO239 assembly on the underside contact the mount?

On a Firestik or other "whip" antenna, the whip itself is basically an extension of the shielded center strand of the coax. The 3/8 x 24 bolt on the bottom of the actual antenna IS the active element and must be isolated from ground. The bushing keeps it from shorting with the outside coupling, or "ground" as it were. The outside barrel of the SO3239 and the outside ring of the PL259 provide the "electrical" ground to the chassis of the RADIO. Again, the bushing isolates the active element, or the whip, from the "ground" portions of the SO239, PL259, and coax...

 

[Ross]

Hoods, hatches, doors, trunks are the worst places when it comes to grounding of any type.

There is paint between where the hinges mount to the rest of the body, that will make the ground less effective. You really should ground to bare metal on the body itself or the frame, not stuff attached to the body.

You probably won't be able to get your SWR low enough to get you radio to work as it good as it can. BUT if you are using it for short distances and you are happy with it then drive on. Older radios could be damaged if the SWR was too high but that shouldn't be a problem anymore.

If you get feedback or static with the radio on, motor off you can probably fix it with a better grounding for the antenna mount (RF grounding). If you get feedback/static with the motor on run you power from the battery and that should fix that issue.

 

[ryannemeth]

Has anyone gotten a good SWR with a setup like this? I currently have a 3' Mag antenna on my roof, but its too tall for my work parking garage.

I'm looking to do a 4' Firestik II with the RS 720 mount (mounted so the antenna ends up about a foot over the roof) but want to make sure ill get decent reception.

Thanks,

 

[Trdmedic]

Presta

How has the comet antenna held up for you. Has it moved, slipped out of place witht weight of the antenna and spring? Where or how did you ground the antenna? Didnt see it in the pics.

 

[Presta24]

the mount has held up well, does move a little if you smack something good with the antenna, paint faded pretty quick too. Im afraid to really torque it down too hard for fear of stripping the threads out so maybe thats why it moves a bit. as far as grounding, i still have not even tuned the cb so im not sure if its grounded well or not. had a lot going on in our lives lately so the truck has just kinda been chillin.