Cobra CB Help - secondary fuse IS NOT needed?

[Csward12]

So, I purchased the Cobra 75 for my JL.

I contacted Cobra directly, and they stated the power box that is being routed directly to the vehicle battery is sufficient and that a secondary fuse IS NOT needed.

Is this correct?

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[WXman]

Technically they are correct. It's not needed. However, I always install inline fuses to be on the safe side.

Good luck with the 75. I have one but its performance is terrible and by the time you mount the little box somewhere and then hang that huge microphone/radio combo off your dash you could just as easily install a real CB radio that actually works. Not knocking you in any way because like I said, I have a 75 also. Just relaying my experience.

 

[Csward12]

Technically they are correct. It's not needed. However, I always install inline fuses to be on the safe side.

Good luck with the 75. I have one but its performance is terrible and by the time you mount the little box somewhere and then hang that huge microphone/radio combo off your dash you could just as easily install a real CB radio that actually works. Not knocking you in any way because like I said, I have a 75 also. Just relaying my experience.

I do appreciate your quick reply, and I value your input.

 

[Fuel Fire Desire]

I have the Midland, which is entirely contained within the hand set, no box. I plug it right into the lighter, and into the antenna coax. Its fuse is within the lighter plug.

THAT SAID.....it is "incorrect". You should always wire a radio directly to the battery (to eliminate ignition noise) and fuse the hot lead somewhere close to the battery. Remember, the fuse isn't just there to protect the circuits of the radio, its there to keep you from burning your jeep down if the hot lead grounds itself between the battery and your radio.

In addition to the Midland CB, I also have a small 25w VHF/UHF (ham) radio in the jeep too. It has THREE fuses. One on the hot lead within 4" of the terminal that connects to the battery (to prevent fires from it grounding to the frame on its path to the radio through the firewall), one on the hot lead coming off of the back of the radio (the radio has a 8" wire harness off the back, so it gets its own fuse to protect that run of wire from grounding fires), and the third is inside the radio within its power supply (to protect the radio itself).

Over redundant? Maybe when viewed as an entire unit, but not when you look at each individual electrical component (the harness coming from the battery, the harness coming out of the radio, and the radio itself). If you are wiring directly to the battery, you're piping in all ~45-ish amp hours from the main battery, un switched, into your passenger compartment. Thats 2 solid amps for 20 hours if theres a short happening somewhere along the way.

After all, an inline fuse kit is what....a dollar or two? Very cheap insurance, and very easy to install.





A side note about the VHF/UHF:

I had originally wanted to (illegally) just amplify my CB to be able to reach the nearest town where I wheel If I ever needed help (about 15 miles away, theoretically 100w on a CB could get you 40-60 miles of range without skip). I decided against it (because its illegal), and went the legal route with an Amateur license and ham radio. THOROUGHLY impressed with this cheap Chinese unit. Im able to hit repeaters in Toledo OH from the south west side of Detroit (38 miles). The big repeater in northern MI where I wheel at has a range radius of 100 miles. So, in theory, assuming I can connect to that repeater from the national forrest 40 miles away, the repeater will retransmit my signal from mid Michigan all the way up to the straights of Mackinac. It also gives you access to the Marine/ MURS/ FRS/ GMRS/ rescue freqs (not legal to talk on with an Amateur license, but if you need emergency help outside of cell range its possible to do so). Not to mention Auto Patches (access to the phone system through the radio) or D-STAR system (internet access).

So much more than just vehicle to vehicle comms within a mile or two. Which, of course, it can still do.

 

[Zoobie]

What mount did you use to hang it on the dash? Looking for what I would mount by Cobra on...

 

[Gaxmode]

Check out cooltechs jl mounts

 

[Csward12]

I have the Midland, which is entirely contained within the hand set, no box. I plug it right into the lighter, and into the antenna coax. Its fuse is within the lighter plug.

THAT SAID.....it is "incorrect". You should always wire a radio directly to the battery (to eliminate ignition noise) and fuse the hot lead somewhere close to the battery. Remember, the fuse isn't just there to protect the circuits of the radio, its there to keep you from burning your jeep down if the hot lead grounds itself between the battery and your radio.

In addition to the Midland CB, I also have a small 25w VHF/UHF (ham) radio in the jeep too. It has THREE fuses. One on the hot lead within 4" of the terminal that connects to the battery (to prevent fires from it grounding to the frame on its path to the radio through the firewall), one on the hot lead coming off of the back of the radio (the radio has a 8" wire harness off the back, so it gets its own fuse to protect that run of wire from grounding fires), and the third is inside the radio within its power supply (to protect the radio itself).

Over redundant? Maybe when viewed as an entire unit, but not when you look at each individual electrical component (the harness coming from the battery, the harness coming out of the radio, and the radio itself). If you are wiring directly to the battery, you're piping in all ~45-ish amp hours from the main battery, un switched, into your passenger compartment. Thats 2 solid amps for 20 hours if theres a short happening somewhere along the way.

After all, an inline fuse kit is what....a dollar or two? Very cheap insurance, and very easy to install.





A side note about the VHF/UHF:

I had originally wanted to (illegally) just amplify my CB to be able to reach the nearest town where I wheel If I ever needed help (about 15 miles away, theoretically 100w on a CB could get you 40-60 miles of range without skip). I decided against it (because its illegal), and went the legal route with an Amateur license and ham radio. THOROUGHLY impressed with this cheap Chinese unit. Im able to hit repeaters in Toledo OH from the south west side of Detroit (38 miles). The big repeater in northern MI where I wheel at has a range radius of 100 miles. So, in theory, assuming I can connect to that repeater from the national forrest 40 miles away, the repeater will retransmit my signal from mid Michigan all the way up to the straights of Mackinac. It also gives you access to the Marine/ MURS/ FRS/ GMRS/ rescue freqs (not legal to talk on with an Amateur license, but if you need emergency help outside of cell range its possible to do so). Not to mention Auto Patches (access to the phone system through the radio) or D-STAR system (internet access).

So much more than just vehicle to vehicle comms within a mile or two. Which, of course, it can still do.

Excellent.

Inline fuse it is!

 

[Csward12]

Ok so, again being new to this(radios, electronics) did this radio already come with an in-line fuse?

 

[jeepdriver99]

Ok so, again being new to this(radios, electronics) did this radio already come with an in-line fuse?

Yep, that is an inline fuse.

 

[Csward12]

Yep, that is an inline fuse.

That’s what I thought, and thanks for the confirmation.

Radios aren’t exactly my specialty!

 

[Fuel Fire Desire]

That’s what I thought, and thanks for the confirmation.

Radios aren’t exactly my specialty!

A couple things to consider, being a radio newb:

Don't ever key the mic without an antenna attached. You'll kill it.

Make sure the antenna is well grounded, not electrically, but with a good RF ground. The tailgate is not grounded to the chassis, so many people run a bonding strap from the gate to the tub. RF travels along the surface of a wire, not through it like electricity, so a simple wire won't work well. A flat woven metal strap (bonding strap) has much more surface area for RF to travel along.

An SWR meter (under $20) will give you a good idea if you have a good RF ground, and if your antenna is tuned. "Ideal" SWR is 1:1, typical CB SWR is 1.5:1, a SWR of 2:1-2.9:1 is really hurting your transmit performance, 3:1 and above is in kill-your-radio territory. All SWR (standing wave ratio) is a unit telling you how much energy is leaving your antenna (good), vs energy being reflected back into your radio (bad).

Heres a short video explaining how to use it, with your exact radio, in a jeep. Its very easy.




Lastly.....I know most jeepers don't care, but a ground plane is important too. Not an electrical ground, not an RF ground, but a plane in which the RF out of your antenna has something to "push off" of. A large flat piece of sheet metal (like a roof) works great....except we have soft tops or tops made of glass. The tailgate, from a radiological point of view, is actually the worst place to put an antenna. Its not grounded well, and theres no ground plane for the antenna to push off of, so the radio waves just kind of flounder around in the immediate area of the jeep. All we have is the hood, and this is about the best you can do, short of popping a hole right in the center.

BUT.....all of that said....if all you're after is comms between you and your buddies in a trail ride within a mile of each other....this doesn't matter. The RF can flounder all it wants, and your buddy 500' in front of you will still be able to hear you just fine. The trucker 4 miles ahead of you on the highway? Not so much.

Before I really understood radio theory, I did everything wrong with my JK (tailgate mount, not grounded, never checked SWR, small antenna even with the roof line) and I still had about 1-2 miles of range. On my JL, where I did everything right (fender mount, proper RF ground, tuned antenna to 1:1 SWR, tall antenna well above the roof, spring mounted), and I get around 4 miles with that cute little Midland.

 

[Csward12]

A couple things to consider, being a radio newb:

Don't ever key the mic without an antenna attached. You'll kill it.

Make sure the antenna is well grounded, not electrically, but with a good RF ground. The tailgate is not grounded to the chassis, so many people run a bonding strap from the gate to the tub. RF travels along the surface of a wire, not through it like electricity, so a simple wire won't work well. A flat woven metal strap (bonding strap) has much more surface area for RF to travel along.

An SWR meter (under $20) will give you a good idea if you have a good RF ground, and if your antenna is tuned. "Ideal" SWR is 1:1, typical CB SWR is 1.5:1, a SWR of 2:1-2.9:1 is really hurting your transmit performance, 3:1 and above is in kill-your-radio territory. All SWR (standing wave ratio) is a unit telling you how much energy is leaving your antenna (good), vs energy being reflected back into your radio (bad).

Heres a short video explaining how to use it, with your exact radio, in a jeep. Its very easy.




Lastly.....I know most jeepers don't care, but a ground plane is important too. Not an electrical ground, not an RF ground, but a plane in which the RF out of your antenna has something to "push off" of. A large flat piece of sheet metal (like a roof) works great....except we have soft tops or tops made of glass. The tailgate, from a radiological point of view, is actually the worst place to put an antenna. Its not grounded well, and theres no ground plane for the antenna to push off of, so the radio waves just kind of flounder around in the immediate area of the jeep. All we have is the hood, and this is about the best you can do, short of popping a hole right in the center.

BUT.....all of that said....if all you're after is comms between you and your buddies in a trail ride within a mile of each other....this doesn't matter. The RF can flounder all it wants, and your buddy 500' in front of you will still be able to hear you just fine. The trucker 4 miles ahead of you on the highway? Not so much.

Before I really understood radio theory, I did everything wrong with my JK (tailgate mount, not grounded, never checked SWR, small antenna even with the roof line) and I still had about 1-2 miles of range. On my JL, where I did everything right (fender mount, proper RF ground, tuned antenna to 1:1 SWR, tall antenna well above the roof, spring mounted), and I get around 4 miles with that cute little Midland.

Thank you for the detailed reply. This radio thing is new to me, and I’m open to any suggestions that come my way. Thanks again.

 

[Csward12]

Ok. Installation complete. Power is fine and channel 1 was 1.2 and channel 40 was 1.4.

The above photos are of the battery and the ground. I was limited to where I could ground due to the length of the wire. Will the ground be safe?

 

[Fuel Fire Desire]

That ground is totally safe. It MAY be a little noisy, but totally safe.

 

[Csward12]

That ground is totally safe. It MAY be a little noisy, but totally safe.

Excellent, thank you.

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