Mobile installs aren't fun

[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...

I only run about 120 watts PEP from the ICOM 7000 & I have never ran High Power in my Mobile except when I was running 400 watts or so with a CB Radio but that was with my Chevrolets & the Toyota which were all NASTY NOISY when the vehicles were cranked up.I have ran a CB in my RAM Pickups with Zero noise issues.I guess they are bonded better than the other Crap that I owned in the past.I Hate noise & on every radio I run that has SSB or AM I run a ClearSpeech DSP Speaker or DSP Base module to remove most all of the white noise & others as well.I have a ClearSpeach speaker on the ICOM 7000 but I honestly don't even need it in this setup most of the time.I know the ICOM 7000 has some Awesome filters as well but I ran one years ago in a Chevrolet & the noise was Terrible with it so I give some Big credit to RAM for the noise reduction.

SIX-SHOOTER
W4KVW

 

[338_MtRushmore]

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

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.

I'm planning on running a straight whip, so I'm expecting to do some matching. Planning on bonding everything. I've never done more than the good and bad in the past.

 

[338_MtRushmore]

I only run about 120 watts PEP from the ICOM 7000 & I have never ran High Power in my Mobile except when I was running 400 watts or so with a CB Radio but that was with my Chevrolets & the Toyota which were all NASTY NOISY when the vehicles were cranked up.I have ran a CB in my RAM Pickups with Zero noise issues.I guess they are bonded better than the other Crap that I owned in the past.I Hate noise & on every radio I run that has SSB or AM I run a ClearSpeech DSP Speaker or DSP Base module to remove most all of the white noise & others as well.I have a ClearSpeach speaker on the ICOM 7000 but I honestly don't even need it in this setup most of the time.I know the ICOM 7000 has some Awesome filters as well but I ran one years ago in a Chevrolet & the noise was Terrible with it so I give some Big credit to RAM for the noise reduction.

SIX-SHOOTER
W4KVW

This is a 2005 dodge ram diesel, and it's not too bad. I had an s9 floor parked next to my wife's Subaru, and after she left it was s1. I gotta double check the cause, but I thought that was odd.

 

[W4KVW]

This is a 2005 dodge ram diesel, and it's not too bad. I had an s9 floor parked next to my wife's Subaru, and after she left it was s1. I gotta double check the cause, but I thought that was odd.

I hear terrible noise from other vehicles on the highway as we pass each other but I'm very pleased with my setup as it is.Low to No Noise is always a good thing.

SIX-SHOOTER
W4KVW
WRMX520

 

[338_MtRushmore]

I hear terrible noise from other vehicles on the highway as we pass each other but I'm very pleased with my setup as it is.Low to No Noise is always a good thing.

SIX-SHOOTER
W4KVW
WRMX520

The noise was the florescent garage light. Near zero noise to S9 with the flip of a switch. That was easy to find lol

 

[fourstringburn]

I'm planning on running a straight whip, so I'm expecting to do some matching.

Just curios to what form of matching you're going to do?

 

[338_MtRushmore]

Just curios to what form of matching you're going to do?

I was planning to try a coil shunt, but I'm not even certain I'm going to do the 1/4 wave whip now.

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 should be able to easily swing 1300 watts, but I still need those big stations to help me on the rx. Do I really want to mess with a flimsy whip flexing all over the place and mess with my standing waves? I have a slightly shorter monkey made that is very ridged, so I think I may try that instead.

Short answer? I'm not sure yet.

 

[fourstringburn]

Ok on the shunt coil. It isn't really necessary unless you're a perfectionist or just want to learn how to do it. It'll work but it does take some trial and error to get the right amount of turns needed. Once you get close, it's just a matter of spreading or compressing the coils.

I used the threads from a 13 mm bolt to form a nice coil. The larger spark plug size will work too.

If that Monkey made is 5 ft or more, that will work very well. I like and used the predator 10k because they are lightweight but sturdy. I recall the overall height was just over 80 inches so on a semi truck, I would smack the whip on some trees and bridges.

Good luck with your mobile install!

 

[W4KVW]

I was planning to try a coil shunt, but I'm not even certain I'm going to do the 1/4 wave whip now.


I should be able to easily swing 1300 watts, but I still need those big stations to help me on the rx. Do I really want to mess with a flimsy whip flexing all over the place and mess with my standing waves? I have a slightly shorter monkey made that is very ridged, so I think I may try that instead.

Short answer? I'm not sure yet.

One Antenna One Standing Wave.No such thing as SWR's on a single antenna for one band.That's why they only sell SWR Meters & Not SWR's Meters. {:>)

SIX-SHOOTER
W4KVW
WRMX520

 

[groundwire]

Forget the whip, use the monkey made. If you do everything right you should be able to get a low vswr without the need for an impedance matching network. I have 2w ref at 6.5kw fwd. It can be done, just take your time, do it right.

 

[338_MtRushmore]

Forget the whip, use the monkey made. If you do everything right you should be able to get a low vswr without the need for an impedance matching network. I have 2w ref at 6.5kw fwd. It can be done, just take your time, do it right.

Edit; I can't believe I asked a question this stupid. I guess I have been using ham gear so long I completely forgot everything I learned about CB.

I only have my hood bonded right now, and my swr always goes up .2 at full output. 100 watts radio only 1.1, radio only driving a few watts with 100 watts out of the amp 1.1. If I slowly turn the drive up it almost linearly goes up to 1.3 at 1,000 watts.

I'm assuming this is just a meter issue, or is it something else like cmc or meter inaccuracy? The meter is an ameritron awm-35bh.

 

[fourstringburn]

something else like cmc...

More than likely!

I use the same meter both mobile and in the shack with no issues.

If you have room to wrap 7 turns of RG8X in a 4 to 5 inch coil and use mix 33 clamp on ferrite beads( but mix 43 will also work on 27 Mhz}.

I believe you are familiar with K0BG's website on how to do this! It worked for me with some CMC issues on my mobile HF rig.

 

[338_MtRushmore]

More than likely!

I use the same meter both mobile and in the shack with no issues.

If you have room to wrap 7 turns of RG8X in a 4 to 5 inch coil and use mix 33 clamp on ferrite beads( but mix 43 will also work on 27 Mhz}.

I believe you are familiar with K0BG's website on how to do this! It worked for me with some CMC issues on my mobile HF rig.

You don't believe the 10 mix 31 beads I have installed are enough, and think the amp is probably clean?

I'll have to research the effects of added power with cmc. I don't recall it causing higher swr, but it's been a long time since I haven't wrapped small coax through a few torroids. I forget a lot these days

 

[fourstringburn]

You don't believe the 10 mix 31 beads I have installed are enough, and think the amp is probably clean?

I'll have to research the effects of added power with cmc. I don't recall it causing higher swr, but it's been a long time since I haven't wrapped small coax through a few torroids. I forget a lot these days

I went back to see your pics, That's not the proper way to choke off CMC from a coax line. You need to coil the coax right under the feed point. The coax coil itself is a form of a choke but the ferrite beads add to the choking impedance to be more effective. More beads can be added if needed like in the pic below.




Here's a link to K0BG website and the chapter on CMC

Common Mode Currents

 

[338_MtRushmore]

I went back to see your pics, That's not the proper way to choke off CMC from a coax line. You need to coil the coax right under the feed point. The coax coil itself is a form of a choke but the ferrite beads add to the choking impedance to be more effective. More beads can be added if needed like in the pic below.

View attachment 59862


Here's a link to K0BG website and the chapter on CMC

Common Mode Currents

I did consider 4-6 turns on 2 large toroids, but all of that wouldn't fit under my headliner. Instead, i did the best I could with the info I could find and substituted lmr400 for the rg213 on the G3TXQ chart. I plan to minimize ground losses as much as possible, and hope to reduce the cmc to a level that doesn't require maximum impedance to be effective.

With that said, I do plan to test the antenna system with a known clean amp and fully expect the swr to remain constant at all power levels. The builder also stated that a rise in swr with increased power should be expected from his amps. I'm assuming I don't need to explain what I believe is causing this added reflection?