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

[Rwb]

This reminds me of what my Dad said when I came home with a brand new Boss 429 He took his pipe out of his mouth he said rev that thing up again so took it up to about 4 grand and let settle down he looked at me and "WHAT THE HELL DO YOU NEED WITH THAT MUCH POWER". I said the same reason you don't need it.

haha

 

[Jay Mojave]

the mobile works perfectly into the dummy load.1w to 4kw is the same, perfect. its the antenna setup somehow.

Ok makes me mad not having the answer, but not the first or last time I am sure.

Suggest using a single antenna and see what you get with that, then add on the second antenna. If it shows a lower VSWR this may indicate something wrong with the second coax/antenna.

It would be great if you could transmit a carrier while a Spectrum Analyzer is looking at the frequencies say from 20 to 200 MHz to look for stronger than normal Harmonics or Spurious emissions possible causing the VSWR problem. Doesn't have too hooked up to the system just near by looking at the spectrum. Again request you let us know the fix on this.

Jay in the Hot Hot Mojave dsert

 

[OldTech03]

I must concur with Mohave in the context " I could be wrong and have been before" but that does not mean you can just ignore suggestions from those of us that have lived in this realm First I have installed and set up more than my share of 5 to 15K mobile systems and when I suggest that maybe HARMONICS could be part of the problem I'm not just guessing it comes from first-hand experience.

Below was my first suggestion: It's given to you in hopes you will try to eliminate the possibility that it is a problem
============================================================================================
Maybe you are experiencing something completely different like harmonics that are rampant this would make it impossible. Are testing with just the radio or at high power Try? Try running coax direct from the radio to the antenna or use an analyzer and short length of coax and maybe you will see a change.
=============================================================================================

NOW:
Putting a dummy load in line isn't a problem as long as you understand that most dummy loads are very broad-banded meaning that if there are harmonics being generated by the amps the dummy load will just see the harmonics as nothing important and still offer you a 1to1 The antenna and coax is not so forgiving it will try to return those harmonics to the meter "ARE YOU FOLLOWING ME?" I'm not trying to be a screamer but you must eliminate this possibility before you continue or you may just be chasing your tail.

DOES ANYONE DISAGREE IF SO PLEASE TELL ME WHERE I'M WRONG.

If you have already run coax from the radio to the antenna and still have the problem then an analyzer can give you some real perspective especially the analyzer you say you are using.

 

[Handy Andy]

Not disagreeing - just providing the back up if you need it...

+1 = Full_Agreement =

DOES ANYONE DISAGREE IF SO PLEASE TELL ME WHERE I'M WRONG.

If you have already run coax from the radio to the antenna and still have the problem then an analyzer can give you some real perspective especially the analyzer you say you are using.

I only hope like h*ll he did have the mod done right...

Mod shown here
​

 

[groundwire]

Ok makes me mad not having the answer, but not the first or last time I am sure.

Suggest using a single antenna and see what you get with that, then add on the second antenna. If it shows a lower VSWR this may indicate something wrong with the second coax/antenna.

It would be great if you could transmit a carrier while a Spectrum Analyzer is looking at the frequencies say from 20 to 200 MHz to look for stronger than normal Harmonics or Spurious emissions possible causing the VSWR problem. Doesn't have too hooked up to the system just near by looking at the spectrum. Again request you let us know the fix on this.

Jay in the Hot Hot Mojave dsert

yea will do.

I must concur with Mohave in the context " I could be wrong and have been before" but that does not mean you can just ignore suggestions from those of us that have lived in this realm First I have installed and set up more than my share of 5 to 15K mobile systems and when I suggest that maybe HARMONICS could be part of the problem I'm not just guessing it comes from first-hand experience.

Below was my first suggestion: It's given to you in hopes you will try to eliminate the possibility that it is a problem
============================================================================================
Maybe you are experiencing something completely different like harmonics that are rampant this would make it impossible. Are testing with just the radio or at high power Try? Try running coax direct from the radio to the antenna or use an analyzer and short length of coax and maybe you will see a change.
=============================================================================================

NOW:
Putting a dummy load in line isn't a problem as long as you understand that most dummy loads are very broad-banded meaning that if there are harmonics being generated by the amps the dummy load will just see the harmonics as nothing important and still offer you a 1to1 The antenna and coax is not so forgiving it will try to return those harmonics to the meter "ARE YOU FOLLOWING ME?" I'm not trying to be a screamer but you must eliminate this possibility before you continue or you may just be chasing your tail.

DOES ANYONE DISAGREE IF SO PLEASE TELL ME WHERE I'M WRONG.

If you have already run coax from the radio to the antenna and still have the problem then an analyzer can give you some real perspective especially the analyzer you say you are using.

radio to antenna, radio and amps to antenna, analyzer to antenna, low pass filter inline, all 1.5, still to much reflected power at high power levels. mfj-854 meter moved a hair when testing common mode current level. so there you go. could be the transmission line itself, measured 46.7ohms or the connectors on them are not 50 ohm (they are not). i have lmr-600 with 50 ohm connectors on the way.

 

[The DB]

So looking back to posts 6 and 7...

Maybe you are experiencing something completely different like harmonics that are rampant this would make it impossible.

Sounds like common mode current on the coax braid?

These are the two things that commonly cause the stated problem. The one in post 7 was apparently confirmed to not be it... I don't recall reading anything that even touched on post 6, which has been reinforced several times after that. Here are examples.

I run a low pass filter in my station and it helps with the SWR. It keeps the RF noise that I generate from going to the antenna, when the harmonic is not a frequency that my antenna is tuned to. The harmonic would normally be reflected to the radio and the low pass nulls it out.

Spurries. There's enough bandwidth product in any amplifier developing power in the kW ranges that WILL amplify the harmonics

Could be an amplifier oscillating. It's not uncommon for a problem child amplifier to work just fine on a dummy load and everything goes to hell when you put it on the antenna.

It would be great if you could transmit a carrier while a Spectrum Analyzer is looking at the frequencies say from 20 to 200 MHz to look for stronger than normal Harmonics or Spurious emissions possible causing the VSWR problem.

Putting a dummy load in line isn't a problem as long as you understand that most dummy loads are very broad-banded meaning that if there are harmonics being generated by the amps the dummy load will just see the harmonics as nothing important and still offer you a 1to1

For now, I'm going to go make some more popcorn and watch as the problem that is almost always the cause of the stated issue continues to be ignored. A possible solution for this was also listed and, of course, was ignored. Of course, I'm not the first person to point this out...

2. that thing that you are SURE it can't be, and by now your brain is passing it over within a second of thinking about it.

The above shows, tells me, you "copy" what others do and think it will all sort itself out.

And finally..

DOES ANYONE DISAGREE IF SO PLEASE TELL ME WHERE I'M WRONG.

I'm not to familiar with who you are, but at least as far as this thread is concerned, I haven't seen anything that strikes me as wrong...

Anyway, back to the popcorn...


The DB

 

[Highway Man]

5k from a 16. That's everyday problems there.
I'm thinking put the limiter in the radio or undo the hack mod or get a different radio. However when you modulate the swr should go flat.

 

[groundwire]

5k from a 16. That's everyday problems there.
I'm thinking put the limiter in the radio or undo the hack mod or get a different radio. However when you modulate the swr should go flat.

5k from a 16? im running my 8 pill like my earlier post says. radio is a yaesu ft-891 like my earlier post says. i dont modify, peak and tweak or any of that stupid shit on my cb radios. your wrong

 

[Highway Man]

Pump your breaks.
What you're describing sounds like a radio issue, improperly tuned box or your antenna is loosing ground. Add a ground strap to your radio if you haven't already.
You'll get it. Let me know cause im installing a 32

 

[loosecannon]

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.

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

 

[groundwire]

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.

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

thats a good idea. i wish i had a way/place to do that. im almost certain its a ground and or coax issue. more than likely ground. i use bird meters and line sections so i dont have an "swr" meter per say.

 

[Blackcat630]

When you get the lmr 600 installed I would remove the pucks and make sure they have a really good bite/bond to the metal. Wire brush and rough up the metal on the underside of the roof and where the backing plate grabs ahold.

 

[Shadetree Mechanic]

5k from a 16? im running my 8 pill like my earlier post says. radio is a yaesu ft-891 like my earlier post says. i dont modify, peak and tweak or any of that stupid shit on my cb radios. your wrong

You are getting 5k from an 8 pill?

 

[groundwire]

You are getting 5k from an 8 pill?

no, i just put that in the title so only people running super high power would respond. not 500w or less people. super high power setups are ALOT more technical and finicky than low power. thats all.hahaha, 5k from an 8 pill. that would be funny. the 8 pill is in use only till i figure this problem out, then the 16 goes back in

 

[Shadetree Mechanic]

no, i just put that in the title so only people running super high power would respond. not 500w or less people. super high power setups are ALOT more technical and finicky than low power. thats all.hahaha, 5k from an 8 pill. that would be funny. the 8 pill is in use only till i figure this problem out, then the 16 goes back in

Haha, ok no problem, for a second there I thought I was going to be "captain obvious" hahaha!

So how much power does the 8 pill put out and are you using a driver amp?