Mobile anybody on here run a high power (5kw+) suburban? i need some advice

loosecannon said:

DB,

The only thing that led me away from thinking about amp tuning and harmonic content was that groundwire stated that he gets a 1.6 SWR when running the Yaesu right to the antenna.
If we trust that the SWR meter being used isn't itself part of the problem, then this leads me to an antenna installation issue, or more likely a grounding issue.
Yeah, at this point i am just guessing.

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I thought I read that with low power his SWR looks fine... Looking back I may have mistook something Beetle said on the first page as coming from him... I am not seeing anywhere where he says his rigexpert reads a lower SWR. If that is the case, my mistake. That being said, if SWR does look fine with his RigExpert, and is higher with his radio and other gear... Your next few lines interest me actually.

loosecannon said:

If it were my vehicle i would do a quick test to help isolate this possible problem.

take that yaesu out of the vehicle, put it on a table right outside of it, and power the yaesu with an external power supply that has zero connections to the vehicle.

this ensures that your vehicle is nothing more than one antenna and whatever groundplane you have made for it by bonding your vehicle together.

the radio's only connection with this system is the coaxial cable that goes from the radio to the antenna through an SWR meter (make sure that SWR meter isn't touching any metal in the vehicle just to be sure).

if testing with the radio isolated from the vehicle produces a lower SWR, then this would point to some sort of grounding issue between the way the radio is installed in the vehicle and the grounding of the antenna.
LC

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If this happens this would likely be the result of a ground loop, which is something that can cause all kinds of problems, some of them appearing to be strange or even intermittent, many of which hide themselves very well and simply cause your equipment to let out the magic smoke at higher rates than would otherwise happen, even when running well within safe power levels and SWR readings. Ground loops are something that almost no one ever considers, but can and does happen in mobile setups, although admittedly fairly rare. Of course, if his rigexpert were were used to test the antenna, and it were run on internal battery power, and he got a lower SWR, (essentially the same thing you recommend only with different equipment) that could also be a sign of a possible ground loop.

On the other hand, if everything is reading an SWR of 1.6, the first thing I would do is remove the passive element on his setup and see how the single so called "hot" element tunes by itself. (I have quickly scanned through ever post and don't recall seeing that this has been done).

I highly doubt that the antenna itself is the issue, I have worked with and seen several of Kale's masterpieces over the years, and not one failed, or caused me to ever question its capabilities. I have seen more than one of these handle more than the advertised 10KW of power with no problems.

But seriously, even if any of this was the case, I would want to see the system myself before making any determination, or calling anything running this much power good. I agree with him that it is a different world, a world that if you are lucky a problem will only be an expensive and timely fix, and if your not lucky...

Of course, I also don't like how these amps are built, but thats another story...


The DB

Or just go out and by a Cobra 19DXVII (or whatever their newest version is...) and try it - or even a $5 Garage sale Midland would work...just try a different radio...in that system, Truck and all...and remove all doubt...

Yep what Handy Andy says, try another radio, try replacing the antennas with 102 inch Stainless Steel whip antennas, I've my A$$ kicked many times wondering into the house playing with my spit having technical problems. When trouble shooting these type of problems one is painted into a corner and forced to try things he thinks are good.

Jay in the Great Mojave Desert

groundwire your beating your self for nothing why don't you call 55=terry he will tell you how long each stinger have to be when using his antenna to a 1.0 to 1.2 swr he will tell how long your coax should be for a suburban when running over 5k. what has work for guys over the years for quick antenna tunning=MFJ 259 antenna analyzer
when i had my astro van with the 3cx3000A i ran 12 1/2 feet of coax from the antenna at 82 or 84 inches apart with a pair 55 3 turn coils hope this helps

Handy Andy said:

Or just go out and by a Cobra 19DXVII (or whatever their newest version is...) and try it - or even a $5 Garage sale Midland would work...just try a different radio...in that system, Truck and all...and remove all doubt...

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Have to agree. I was having excessive noise issues. Tired all sorts of stuff. Was recommended by the gents here and the engineer at Palomar to try a different radio. Well what do you know...noise went away!!

Another dickhead running 50 times more power than they need into a shitty antenna install where there isn't enough bodywork on the entire vehicle to provide a sufficient ground plane, using coax which is nowhere near rated high enough power rating even with a perfect 1:1 SWR let a SWR anything above that which would require an even more beefy coax and they're wondering why they've got issues?

I know what the solution is and that's to get real with what power you can run in a mobile installation. It is not possible at all to run 5kW on a mobile installation without any issues. You're always going to have common mode unless you implement the kind of RF ground you'd find at the transmitting site of a shortwave broadcast station and with that kind of RF ground you're not going to be driving around.

Dickheads running kilowatt plus on CB need to be caught by the authorities, their equipment confiscated and five figure fines given for the misery they cause everyone who is unfortunate enough to be anywhere on the 11m band at the same time they are. Because of the poor selectivity of CB radios you selfish bastards literally wipe out the entire 40 channels for everyone else every time you key up.

It's a good thing this is in the CB section then.

He did post this in CB Antennas - so it comes to mention that using a Ham radio - with a CB antenna - but never really told us what channel that he would use it on...

Er, OOPs- Sorry...Not Channel...I meant FREQUENCY...

(Ahemn...)

Attention-Getter Thread Title.

Go-Pro on at key-up.

Memento Mori

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Another butthurt duck

M0GVZ said:

Another dickhead running 50 times more power than they need into a shitty antenna install where there isn't enough bodywork on the entire vehicle to provide a sufficient ground plane, using coax which is nowhere near rated high enough power rating even with a perfect 1:1 SWR let a SWR anything above that which would require an even more beefy coax and they're wondering why they've got issues?

I know what the solution is and that's to get real with what power you can run in a mobile installation. It is not possible at all to run 5kW on a mobile installation without any issues. You're always going to have common mode unless you implement the kind of RF ground you'd find at the transmitting site of a shortwave broadcast station and with that kind of RF ground you're not going to be driving around.

Dickheads running kilowatt plus on CB need to be caught by the authorities, their equipment confiscated and five figure fines given for the misery they cause everyone who is unfortunate enough to be anywhere on the 11m band at the same time they are. Because of the poor selectivity of CB radios you selfish bastards literally wipe out the entire 40 channels for everyone else every time you key up.

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Good thing no one listens to you anyway. More BS from the know it all.

I've helped a quite a few guys in the past with this same scenario. Like I said in my earlier post on the first page, I think your hot antenna is too close to the center of the roof. A quarter wave antenna that is direct fed needs to see at least some sloping ground plane close to the base to match correctly. With too much flat ground plane around the base of the antenna you have to add inductance to the feedpoint to get it up to 50 ohms. Try running one antenna by itself on the rear puck. If you are able to tune the antenna then my suspicion is correct.
I know it will be a buzzkill to have already cut holes in you rig just to find out they were cut in the wrong spot but that's how it rolls sometimes in the CB antenna game.

I see the examples of other guys you posted and I couldn't tell you what they did to make it match, I'm just telling you what has been my experience.

Maybe you can isolate the front mount and use it as a director and make a trailer hitch reflector system.

DoctorAudio said:

I've helped a quite a few guys in the past with this same scenario. Like I said in my earlier post on the first page, I think your hot antenna is too close to the center of the roof. A quarter wave antenna that is direct fed needs to see at least some sloping ground plane close to the base to match correctly. With too much flat ground plane around the base of the antenna you have to add inductance to the feedpoint to get it up to 50 ohms. Try running one antenna by itself on the rear puck. If you are able to tune the antenna then my suspicion is correct.
I know it will be a buzzkill to have already cut holes in you rig just to find out they were cut in the wrong spot but that's how it rolls sometimes in the CB antenna game.

I see the examples of other guys you posted and I couldn't tell you what they did to make it match, I'm just telling you what has been my experience.

Maybe you can isolate the front mount and use it as a director and make a trailer hitch reflector system.

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I've saw this happen with pucks centered on a pick up truck. I mounted mine as far back as I could and had no issues....once the amp was tuned properly.

The short shaft Davemade antennas have an adjustable shunt. That migh be worth looking into. I've wanted to try an inductor or cap at the feed point but haven't had the opportunity. The last guy gave up and put a 102 on the bumper.

543_Dallas said:

I've saw this happen with pucks centered on a pick up truck. I mounted mine as far back as I could and had no issues....once the amp was tuned properly.

The short shaft Davemade antennas have an adjustable shunt. That migh be worth looking into. I've wanted to try an inductor or cap at the feed point but haven't had the opportunity. The last guy gave up and put a 102 on the bumper.

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“As back as I could” . . . meaning cab roof (I take it).

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