Cobra 75 WX ST / Wilson FLEX Install

[Dante's Taco]

Well, for anone who remembers how many times I picked up my magtnet-mount antenna after the last two runs at Waiparous, you'll know why I wanted a new antenna. Of course, I couldn't pass up the chance to get a CB that wasn't made in 1989, so... :D

I'll post this install in parts.

Part 1 - the stuff arrives:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1752.jpg

I got a package from RightChannelRadios out of the US:

Cobra 75 WX ST
Wilson Silvertip FLEX 4 foot antenna
Stainless Steel Adjustable Universal Hood Channel Mount
18' Belden Coax
Uniden external speaker
Opek SWR meter & jumper coax
Firestick Quick Disconnect

I'll do the install this weekend & post up some pics after.

First question:
Do you guys think I'll need to add extra grounding straps, from the driver's side to other major metal on the chassis (like I've read on some web-sites they do fender-to-engine, fender-to-frame, box-to-frame, etc using metal braid?) I know I'll need to ensure a good ground on the actual antenna mount; I'm just wondering if anyone spent more time on ensuring the whole truck is well grounded.

Thanks!

Geoff

[tacotaco]

Your old antenna was awsome, it kept you busy stepping in and out of your truck to put it back on.

[Sprockett]

Interested to see how this goes Geoff. I have the same CB installed but I'm debating the antenna mount. The mag mount I've been using is a friends.

Thinking fender mount like you or just a tab welded to the rear bumper.

[Tarzan]

Funny thing is I use my cb less and less and have thought about removing it. Most trail runs these days people are using frs and the only time I use cb is as tail gunner or trail leader. I do prefer cb over frs and of course vhf is the ultimate way to communicate. We should run a poll on what people use for communication.

[FJeff Cruiser]

Hey Geoff... nice upgrade. Now we need to convince Ryan to give the mag mount back to his friend and upgrade too : )

[Dante's Taco]

Funny thing is I use my cb less and less and have thought about removing it. Most trail runs these days people are using frs and the only time I use cb is as tail gunner or trail leader. I do prefer cb over frs and of course vhf is the ultimate way to communicate. We should run a poll on what people use for communication.

Maybe it's my old ears, or people/or I have crappy FRS, but man, I find it super hard to hear clear, intelligible conversations on FRS. It's like being on the trail with Charlie Brown's teachers...

So I'm going the other way, from FRS to CB

Plus not having the batteries go dead on the FRS, and the ++ better range; hands down, CB kicks IMHO.

I still bring them (FRS) along; but I find CB WAY better for comms

[freeze]

I was impressed with the range when driving down to the Rubicon with David E. and Gary. I was a good 8K behind in the valley and was able to communicate on the highway no problem.

I look forwards to the updates Geoff!

[Doc McCoy]

Yeah, I think I have to do a bit more tuning on mine. David E and I would be crystal clear at some points and then some messages just wouldn't get through.

I have almost all the pics from my install ... I should do a write-up in case Chris wanted to get a Uniden. :D

[Tarzan]

I agree that cb is far better than frs but it's just that nobody seems to be usng cb as much. frs main advantage is it's cheaper, simpler and mobile. Glad to see more cbs being used so I will keep mine. Vhf is to cb what cb is to frs when it comes to communication.

[Doc McCoy]

Harry, the team is fast aproaching getting all of us certified to be on VHF. In the mean time most of the team is now running both CB and FRS.

(Then we'll be able to give you a hand next year with the rally stuff ;) )

[mookie]

Well, for anone who remembers how many times I picked up my magtnet-mount antenna after the last two runs at Waiparous, you'll know why I wanted a new antenna. Of course, I couldn't pass up the chance to get a CB that wasn't made in 1989, so... :D

I'll post this install in parts.

Part 1 - the stuff arrives:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1752.jpg

I got a package from RightChannelRadios out of the US:

Cobra 75 WX ST
Wilson Silvertip FLEX 4 foot antenna
Stainless Steel Adjustable Universal Hood Channel Mount
18' Belden Coax
Uniden external speaker
Opek SWR meter & jumper coax
Firestick Quick Disconnect

I'll do the install this weekend & post up some pics after.

First question:
Do you guys think I'll need to add extra grounding straps, from the driver's side to other major metal on the chassis (like I've read on some web-sites they do fender-to-engine, fender-to-frame, box-to-frame, etc using metal braid?) I know I'll need to ensure a good ground on the actual antenna mount; I'm just wondering if anyone spent more time on ensuring the whole truck is well grounded.

Thanks!

Geoff

'Ello!

Look at all your new goodies!!

You can take the effort to run grounding straps, but you're working with a CB-not much gain here unless you are having tx/rx problems. Don't get DC ground confused with RF ground. Your antenna needs an excellent RF ground so focus on that.

If this was for a vhf/hf install, then yes, grounding braids are usually necessary.

[freeze]

(Then we'll be able to give you a hand next year with the rally stuff ;) )

I hope I pass!! Gotta fit studying for the exam in somehow!

Can't wait to help out when I have my license too!

[freeze]

You can take the effort to run grounding straps, but you're working with a CB-not much gain here unless you are having tx/rx problems. Don't get DC ground confused with RF ground. Your antenna needs an excellent RF ground so focus on that.

If this was for a vhf/hf install, then yes, grounding braids are usually necessary.

Hey Kevin!

I ended up getting this bumper mount thing from Comtek that seemed to do the trick?

http://www.gijoesradioelectronics.com/Images/WilsonCbAntennaHeavyStuds.jpg It's the metal one to the right.

It's isolated from the bumper but has a ground. What's an optimal RF ground?

[Tarzan]

You can help with recovery with out vhf radio as long as you are with somone who has one ie me. As long as I can communicate with those helping me one radio will work. Sometimes it takes two or three to extract a vehicle that has gone off. When rally cars go off they really go off ie upside down backwards into trees at the bottom of ravines it's wild.


Harry, the team is fast aproaching getting all of us certified to be on VHF. In the mean time most of the team is now running both CB and FRS.

(Then we'll be able to give you a hand next year with the rally stuff ;) )

[Dante's Taco]

Thanks Mookie

I guess I'll not bother with strapping the various big chunks together. I could always add that later if I get bored..
By RF ground, do you mean ensuring the antenna is radiating off an appropriate metal surface (as opposed to like, a fiberglass topper or something)? Is this also called "ground plane"?

Here is what I've got done so far:

The mount is installed (I added more SS screws after this shot was taken):
http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1753.jpg

Using a multimeter, I was able to show continuity between various metal objects / ground points, and the antenna mount.

Here it is with antenna installed on mount. I've got at least 2/3 of element above cab roof line, and it's pretty true to vertical.
http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1756.jpg

Here is a close up of the quick-disconnect. Ignore the lead tied to the base of the antenna - it's an impedance matching lead, which I hopefully won't need.:
http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1757.jpg

Using multimeter, the part above the nylon washer (i.e. the antenna element) is NOT showing continuity with any ground points on truck.

For tomorrow: Running Coax & power!

[mookie]

Hey Kevin!

I ended up getting this bumper mount thing from Comtek that seemed to do the trick?

http://www.gijoesradioelectronics.com/Images/WilsonCbAntennaHeavyStuds.jpg It's the metal one to the right.

It's isolated from the bumper but has a ground. What's an optimal RF ground?

I like that. I think I may pick one up as well. Make it the shortest length from your antenna mount to the best "grounded" point to your chassis. That RF ground wire/strap is actually an antenna, but you want to make it the lousiest antenna.

[Dante's Taco]

Today I ran the Belden Coax & power wires.

I found a nice big wire loom/grommet on the Driver's side, by the MBC. I used a bent coat hanger as my "fishing hook" to pull the coax through the grommet, from engine side of the firewall, into the cab:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1758.jpg

Here you can see coax going into grommet up closer:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1760.jpg

After that pic, I did same thing with DC 13.8V wires (fused). I am running direct to battery for now, to minimise any chance of picking up interference from the truck's electrical system. That does mean if I leave the radio on, it will draw from battery even without key in though..
Down the road, I may put in a secondary fuse/bus box for my add-ons like this.

The wires come out just behind the E-brake pedal in the cab; I ran them up & behind all pedals to the centre console, where I'll be installing the Cobra junction box & radio quick-disconnect. I read you can't coil the excess coax (apparently creates a "choke" & will reduce signal), so I made more random loops/dogbones with excess coax. From in the cab, you can't see any of this, which is nice from an anti-theft point of view; and it's nice not having loose wires about.

Next up: radio in the cab: That'll be tomorrow or Sat!

[freeze]

Amazing write up as usual Geoff! Keep up the great work ;)

[Dante's Taco]

Today I worked on finding a place this little guy:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1766.jpg

That is the Cobra junction box - everything, including the radio itself, plugs in here. I first of all was going to put it under the cup holders:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1761.jpg

But there wasn't enough clearance underneath, and also, would have had to drill to mount. Instead, kept taking things apart:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1762.jpg

There was a handy mounting bolt on the right side of the shifter assy (that will have a good ground for the junction box), and lots of room to spool all the excess wiring. Now we're getting somewhere!
Here's a close up the mount bolt I used:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1764.jpg

So here it is in place:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1767.jpg

And with cup holder back in

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1769.jpg

For tomorrow, all that's left is to fit the quick-disconnect for the actual radio into the coin tray/shifter moulding, find a spot for the mike hanger (still thinking about that one..) and then tune the antenna with the SWR meter.

cheers

[freeze]

Very cool! breaker breaker 1-9! psssshhhht

[Dante's Taco]

Well, it's basically done as of tonight. Didn't get around a few final things (tuning antenna, mike hanger) but that shouldn't take too long.

Today I installed this:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1773.jpg

I decided to drill out the coin holder to put in the quick-disconnect. the mounting bracket fits *perfectly* here - like it was meant for this or something.

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1774.jpg

Here it is, in place, without handset plugged in:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1872.jpg

I think it's a fairly clean install; pretty much out of the way when not using.
And here it is powered up:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1875.jpg

So, anyone got any thoughts where to mount the microphone hanger clip? Ryan, you have one of these Cobras - where would you put it (the hanger)?
I can't decide between a couple of locations:

on the dash, other side of the clock from the 4Hi/Lo switch
higher up, between the 2 map lights - the cord dangling down might be a bad idea though


that's all for today

[Sprockett]

Hey Geoff,

I've yet to pick up my mic hanger...will get it along with the antenna from Comtek when I get around to it. I'll definitely put it on the dash though...somewhere that the cord will be out of the way and not flopping around is the most important to me. So, I guess you could tell I'd not choose to mount on the roof :)

[Dante's Taco]

Well, this is the last segment of the install post.

Sprockett: "I'll definitely put it on the dash though...somewhere that the cord will be out of the way and not flopping around is the most important to me. So, I guess you could tell I'd not choose to mount on the roof"

After thinking about it - I agree. I went here:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1886.jpg

Then we tuned the antenna with the SWR meter & jumper that came with the kit:

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1883.jpg

I got it down to 1.1 pretty much equally on channels 1 and 40. The FLEX had a little Allen wrench to loosen the coil top, and a brass tip can go up or down to tune it.

The radio seems to work well to all who've heard it; and got some skip this morning - heard Spanish & major Southern' drawl!
I like having the Weather Radio feature as well - comes in super clear.

I'll be bringing the SWR meter along on runs if anyone wants to borrow it - I guess I won't need it again unless something changes on this setup.

cheers

[freeze]

Very nice write up Geoff and clean installation! I'm excited to see it in person on the trail this month.

[tacotaco]

http://i293.photobucket.com/albums/mm68/dantes_taco/Cobra%2075WX%20ST/IMG_1872.jpg

Hey Geoff that's a nice install looks good, might I suggest a cap or a cover for the mike connection. If you leave the mike connected all the time it would be good but if not, you might end up getting some garbage stuck in the connection and may not be able to plug it in or end up with a bad connection.

[freeze]

Hmmm a nice aluminum connection cover would look swell with CT4WD stamped into the top :D

[Dante's Taco]

Yeah I wondered about covering that... so far I've been playing with the radio a lot, so it's been in 24/7.

I think I could scrounge up something from the random junk in the garage. And yes, Nathan, I'll have to try making a graphic for the cap :D