Mobile installs aren't fun

[338_MtRushmore]

Working on a mobile 8 pill install and figured I'd share some pics so y'all can tell me how I should have done it lol. I'm still waiting on my bonding stuff to arrive next week, but I want my headliner back in.


Amp ground wire crimped, soldered, butyl wrapped and covered with tape. Added just a dash of no ox on the ring.


Sealed both sides with butyl and heated up to get good adhesion. Both sides of the bolt got the same treatment.
View attachment 59810
I forgot my 10 31 mix chokes, so I had to bend the ground ring to squeeze them on. I didn't really want to try loops of lmr400 through a big torroid, so I'm trying this. Probably a terrible choke, but at least I tried?

Wrapped choke in tape and foam, butyl sealed the coax and probably too much no ox on the terminals. The aluminum plate (I wasn't thrilled about using diamond plate) is glued to the roof except for the area of the steel backing plate which was cleaned of pain on the roof and oxidation on the aluminum. Once again, a helping of no ox was applied. The puck is much more ridged than when it was mounted to the roof alone.

Hot wire to the amp no oxed and installed into the LC-10 connector.

I have my fuse box mounted and will probably try to get the power ran to the amp and figure out where my Ic-7100 is going to be mounted. That is all for now

 

[338_MtRushmore]

Glued and almost ready for install


I think the plate is 19"x24". Well worth the effort unless the no ox fails me and I have ground issues. I dunno

 

[SIX-SHOOTER]

I have ZERO bonding with my mobile antennas.I am running Hustler Resonators on the 22" mast & using my ICOM 7000 in my 2007 RAM 1500 Quad Cab.I have the antenna mast attached to the passenger side bed stake on the rear of the bed.I have no noise from the truck & it's the quietest mobile install I have ever had.The Chevrolets were like running a blender whenever the truck was cranked up but not so with the RAM.It's as quiet in my mobile as it is on my base except when crossing under power lines so the Interstate is Great.I have one snap on ferrite on the coax at the antenna base,one on the power cord for the radio,& one at the battery connection.That's all.

SIX-SHOOTER
W4KVW

 

[338_MtRushmore]

I have ZERO bonding with my mobile antennas.I am running Hustler Resonators on the 22" mast & using my ICOM 7000 in my 2007 RAM 1500 Quad Cab.I have the antenna mast attached to the passenger side bed stake on the rear of the bed.I have no noise from the truck & it's the quietest mobile install I have ever had.The Chevrolets were like running a blender whenever the truck was cranked up but not so with the RAM.It's as quiet in my mobile as it is on my base except when crossing under power lines so the Interstate is Great.I have one snap on ferrite on the coax at the antenna base,one on the power cord for the radio,& one at the battery connection.That's all.

SIX-SHOOTER
W4KVW

I've done some quick and dirty installs and had pretty good luck up to about 200 watts. Anytime I went over 300 I'd have problems. I'm just trying to do the best I can with a limited understanding.

It would be pretty nice if one could just install a "ground loss meter" and know where they stood. I'm going to bond the heck out of this one and hope for the best. Stay home, or swing for the fence...

 

[groundwire]

Yikes!

 

[338_MtRushmore]

Yikes!

How bad is it?

 

[1iwilly]

How bad is it?

on your 1st pic is the bolt all the way tighten ?? cause that connector should be flat to the metal also you going to run 1 antenna or 2 antennas= bounce back system ??

 

[338_MtRushmore]

on your 1st pic is the bolt all the way tighten ?? cause that connector should be flat to the metal also you going to run 1 antenna or 2 antennas= bounce back system ??

It isn't even snugged up yet. It's mostly just showing the clean spot on the rusty frame and the strip of butyl behind the back edge of the ring to get a watertight seal. Just running a single antenna, not many keydown competitions around here.

 

[ForestRunner98]

I am diggin it!! Why the Diamond plate? Just curious. BBI does the butyl thing too! Saw some things on that vid that I applied in my build as well.

Looking forward how this turns out!!!

 

[338_MtRushmore]

I am diggin it!! Why the Diamond plate? Just curious. BBI does the butyl thing too! Saw some things on that vid that I applied in my build as well.

Looking forward how this turns out!!!

The plate is just to reinforce the roof... stole that from BBI, along with the butyl. I tried my best to take the best of the cb world along with the ham stuff. I've never heard of choking coax on a 1kW+ cb install, and k0bg's star washers are a proven joke.

I was swinging 1kW+ tonight and the truck didn't go haywire on me, so that is a good sign. In my driveway between 2 other vehicles my swr was good, but in an open parking lot it was 1.4. Need to get it bonded and a final tune to see how she does.

It's a giant waste of money, but I'm being entertained so I guess it's worth it? I think I just need to buy the 3kW ameritron meter and I'll be set. Or maybe a cobra 29 and a driver to try out AM...

 

[M0GVZ]

It would be pretty nice if one could just install a "ground loss meter" and know where they stood. I'm going to bond the heck out of this one and hope for the best. Stay home, or swing for the fence...

You can. What you need is an antenna analyser, a quarter wave whip for the frequency you want to operate on and a very very short length of coax to go from the mount to the antenna analyser.

As we know the feedpoint impedance of a 1/4 wave antenna at resonance over a perfect ground is 36.8 Ohms. So with an antenna analyser you find the point of resonance, where X=0, and see what the impedance is. The further away from 36.8 Ohms you are the worse your RF ground.

Doing that you can also test for improvements. First of all when starting note the resonant frequency where X=0. As we know the more you improve your RF ground the shorter the radiator needs to be for a given frequency. So what will happen is as you improve your RF ground, because you're not changing the length of the whip the resonant frequency will lower. Any bonding you do where it has no effect on the resonant frequency isn't doing much at all. The bigger the drop when you add bonding the more effect that particular part you bonded has on your RF ground.

Nearest I've got with all the bonding on my car was 37 Ohms on 11m. And I find that with every mobile CB antenna I get, such as the Sirio 5000 I'm currently using, I have to get the dremel out and cut off 2-3" to raise the frequency to within the range of CB as they're typically around 26.000MHz out of the box.

 

[338_MtRushmore]

You can. What you need is an antenna analyser, a quarter wave whip for the frequency you want to operate on and a very very short length of coax to go from the mount to the antenna analyser.

As we know the feedpoint impedance of a 1/4 wave antenna at resonance over a perfect ground is 36.8 Ohms. So with an antenna analyser you find the point of resonance, where X=0, and see what the impedance is. The further away from 36.8 Ohms you are the worse your RF ground.

Doing that you can also test for improvements. First of all when starting note the resonant frequency where X=0. As we know the more you improve your RF ground the shorter the radiator needs to be for a given frequency. So what will happen is as you improve your RF ground, because you're not changing the length of the whip the resonant frequency will lower. Any bonding you do where it has no effect on the resonant frequency isn't doing much at all. The bigger the drop when you add bonding the more effect that particular part you bonded has on your RF ground.

Nearest I've got with all the bonding on my car was 37 Ohms on 11m. And I find that with every mobile CB antenna I get, such as the Sirio 5000 I'm currently using, I have to get the dremel out and cut off 2-3" to raise the frequency to within the range of CB as they're typically around 26.000MHz out of the box.

That is a pretty good explanation. I hope it helps someone understand that their "flat match" (I hate that term lol) is actually a bad thing.

While my mount was out I drilled and tapped it in case I did something right and needed a shunt. (It was starting to rain so I just stuck a no-oxed bolt in there temporarily)

 

[1iwilly]

You can. What you need is an antenna analyser, a quarter wave whip for the frequency you want to operate on and a very very short length of coax to go from the mount to the antenna analyser.

As we know the feedpoint impedance of a 1/4 wave antenna at resonance over a perfect ground is 36.8 Ohms. So with an antenna analyser you find the point of resonance, where X=0, and see what the impedance is. The further away from 36.8 Ohms you are the worse your RF ground.

Doing that you can also test for improvements. First of all when starting note the resonant frequency where X=0. As we know the more you improve your RF ground the shorter the radiator needs to be for a given frequency. So what will happen is as you improve your RF ground, because you're not changing the length of the whip the resonant frequency will lower. Any bonding you do where it has no effect on the resonant frequency isn't doing much at all. The bigger the drop when you add bonding the more effect that particular part you bonded has on your RF ground.

Nearest I've got with all the bonding on my car was 37 Ohms on 11m. And I find that with every mobile CB antenna I get, such as the Sirio 5000 I'm currently using, I have to get the dremel out and cut off 2-3" to raise the frequency to within the range of CB as they're typically around 26.000MHz out of the box.

i hope I'm understanding right but everyone i know on Mobil we always ended around 48 to 50 ohms 1.1 or 1.2 SWR at 10,000 watts reflect of 4 watts 49/50 ohms then we put a field strength meter on the dash with radio at 4 watts dead key we finish adjusting the whip for maximum which was less than a C hair everything else didn't change

 

[fourstringburn]

i hope I'm understanding right but everyone i know on Mobil we always ended around 48 to 50 ohms 1.1 or 1.2 SWR at 10,000 watts reflect of 4 watts 49/50 ohms then we put a field strength meter on the dash with radio at 4 watts dead key we finish adjusting the whip for maximum which was less than a C hair everything else didn't change

10kw on a mobile?

What M0GVZ says is correct pertaining to a 102" whip that the feed point impedance is 36.8 ohms because there is no matching coil or anything else to bring the feedpoint up to 50 ohms.

I once checked one myself on an analyzer and it shown the same.

Typical metal rod CB mobile antennas that are 4 to 5 ft or longer which obviously are shorter than a full length 1/4 wave whip on 27 mHz use loading coils to bring up the lowered feedpoint impedance due to a shortened antenna. The shorter the antenna on a given frequency, the lower the feedpoint impedance will be and the need to bring up to a tune-able range. This also means more losses.

This is the trade off with shorter antennas. They provide a much more manageable height and being tune-able for the best match, but the coil has some rf losses due to it's inductance properties. This is where a 1/4 wave whip is more efficient because it has no coil losses. However, A little loss with a coil antenna at 10kw isn't going to be noticed on the other end!

I assume you're using a metal rod type antenna with a coil on it or the device you're measuring your antenna with isn't accurate if you're using a 1/4 wave whip.

 

[ForestRunner98]

The plate is just to reinforce the roof... stole that from BBI, along with the butyl. I tried my best to take the best of the cb world along with the ham stuff. I've never heard of choking coax on a 1kW+ cb install, and k0bg's star washers are a proven joke.

Ya I have a metal plate under my roof to support a Sirio 5K. Just wondering about the Diamond plate. I figure it’s what you had laying around to use.

I have 6 snap on beads(mix 31) near the feed point under the headliner. I also have a choke wrapped around a mix 61 toriod(12 times) at amp TX side. Near close to 50ohm looks good on smith chart and 1.1 SWR. Got good advice from peeps here and BBI’s vid. 4 bonds on each side of truck frame to body as well as doors, hatch, hood, motor, exhaust….phew.