How much of a performance hit is there running CB off of a fuse block?

Steel City 06 said:
The clamp meter is on the DC mode in those photos. On the screen there is either a ~ symbol or the solid line/dashed line symbol. One of the buttons toggles AC/DC.

Look immediately left of the numbers (up in reference to the first photograph orientation).

In addition, the engine is off in those photos.
Click to expand...
Missed that... If the engine is off, what is drawing all that current?
Steel City 06 said:
The clamp meter is on the DC mode in those photos. On the screen there is either a ~ symbol or the solid line/dashed line symbol. One of the buttons toggles AC/DC.

Look immediately left of the numbers (up in reference to the first photograph orientation).

In addition, the engine is off in those photos.
Click to expand...
So you cranked the headlights, heater blower, etc. for current draw?
Going to have to get me one of those meters... $118 on amazon IS in my price range.
The last time I looked they were 5-7 times that much.
I have a number of shunts that I use inline, that meter simplifies that process a LOT!
 
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Jeepn_Texas said:
Missed that... If the engine is off, what is drawing all that current?

So you cranked the headlights, heater blower, etc. for current draw?
Going to have to get me one of those meters... $118 on amazon IS in my price range.
The last time I looked they were 5-7 times that much.
I have a number of shunts that I use inline, that meter simplifies that process a LOT!
Click to expand...
Pretty much. I believe it was headlights, high beams, KC spots, and KC fogs (all of which are halogen/incandescent). So probably about a 600 watt resistive load.

That meter is a really handy tool. One of my most used electronic tools.

Just be aware if you clamp it on a power wire like to an appliance or something, it won't read anything. It measures net current, so if you have both the supply and ground in the loop, the net current is zero, and it will show zero. I made that mistake out of the box and thought it was broken. Quickly realized I was just an idiot haha.

With DC amps you have to zero it every ti e you use it. Just zero it in free air before you clamp it on something
 
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Steel City 06 said:
Pretty much. I believe it was headlights, high beams, KC spots, and KC fogs (all of which are halogen/incandescent). So probably about a 600 watt resistive load.

That meter is a really handy tool. One of my most used electronic tools.

Just be aware if you clamp it on a power wire like to an appliance or something, it won't read anything. It measures net current, so if you have both the supply and ground in the loop, the net current is zero, and it will show zero. I made that mistake out of the box and thought it was broken. Quickly realized I was just an idiot haha.

With DC amps you have to zero it every ti e you use it. Just zero it in free air before you clamp it on something
Click to expand...

You are not an idiot, you were ignorant!
An Idiot is not rectifiable, Ignorance is simply a matter of education!
How current flows in a system and how it is measured is not intuitive
until you have experience in how current manifests itself.
You learned and now you have the ability!

I know them well but when I used them in Electronics Engineering where THEY paid for by them.
Wow, the prices have come down and quality have come up pretty good since I last looked at them.
Yes, I am going to get me one of those!
On the AC measurement, the two leads together null the magnetic field,
that's why PCB designers like myself use Differential pair routing,
the signal and the return null the electromagnetic field around the pair and
help keep them from imposing that signal or even data onto the ground, power or other signals.
It also resists other noise fairly well.

That is why Common mode filtering in a car is so important. Especially right at the battery.
Then minimal filtering at the radio to remove any other noise and RF that may be induced.
I run 100 watts on HF so getting that into vehicle wiring is not good!
Alternator whine is caused by the rectified wave forms above the overlap
of the rectified 3 phase outputs. On my jeep it is about 120mv.
Consider 50-60 amps of 120mv AC on your 14 volt DC at freeway speed.
That's about 6.6 watts worth of noise.
I get as much as 2.6A of parasitic AC current right at the battery.
 
Jeepn_Texas said:
You are not an idiot, you were ignorant!
An Idiot is not rectifiable, Ignorance is simply a matter of education!
How current flows in a system and how it is measured is not intuitive
until you have experience in how current manifests itself.
You learned and now you have the ability!

I know them well but when I used them in Electronics Engineering where THEY paid for by them.
Wow, the prices have come down and quality have come up pretty good since I last looked at them.
Yes, I am going to get me one of those!
On the AC measurement, the two leads together null the magnetic field,
that's why PCB designers like myself use Differential pair routing,
the signal and the return null the electromagnetic field around the pair and
help keep them from imposing that signal or even data onto the ground, power or other signals.
It also resists other noise fairly well.

That is why Common mode filtering in a car is so important. Especially right at the battery.
Then minimal filtering at the radio to remove any other noise and RF that may be induced.
I run 100 watts on HF so getting that into vehicle wiring is not good!
Alternator whine is caused by the rectified wave forms above the overlap
of the rectified 3 phase outputs. On my jeep it is about 120mv.
Consider 50-60 amps of 120mv AC on your 14 volt DC at freeway speed.
That's about 6.6 watts worth of noise.
I get as much as 2.6A of parasitic AC current right at the battery.
Click to expand...


I’ve dug through this stuff before as well. I used to be into car audio, so a lot of that is applicable to this as well. My previous experience tells me that these problems could be easily reduced. For example, higher end high-output alternators are six-phase, as opposed to three-phase. Thus the ripple current on the alternator is far less significant. Also, use of a large enough capacitor could filter out the vast majority of the noise. The 65 farad capacitor I linked should be able to dramatically filter out a lot of the ripple current from the entire system. And capacitors of that size are quite cheap these days.
 
Jerry Bransford said:
Performance isn't the issue, electrical noise that can make it into your transmitted and received signals is the biggest potential issue. So it depends on where that fuse block is getting its power from. If there is something electrically noisy sharing that power source, like the fuel pump, alternator, etc. the CB would probably pick up that noise.

Which is why Basic- 2-Way Radio Installation 101 says 2-way radios should be powered from as close to the battery as possible. One good source of power is the 12v input lug on the firewall-end of the Power Distribution Center. The input lug is under a small black flap that lifts up to expose the lug.

This is mine, I have my two 2-way radios and a small aux fuse panel connected to it. Both this point and the battery are two very quiet (electrically speaking) attachment points, no filter capacitor is needed for either.

View attachment 114344
Click to expand...
WhenI lift up the cover on my power distribution center I see two lugs with nuts on them (I think I am looking in the correct place. Can I wire my red cb radio wire to either one of these? I have. 2003 TJ.
 
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