Extremely High SWR Readings

[Kawasaki7410]

I recently installed a used Cobra 18 WX ST II in my Ford Ranger. I was using a small window mount antenna but it just wasnt strong enough for me. I got a 4 ft Everhardt Tiger off one of my buddies and a 5 in magnetic base which I put on the roof. It was working okay, but I wanted to tune it to get better performance. Yesterday I went to tune it and I was getting an extremely high SWR reading, about 6-8. What could cause this? Is my radio causing it?

[jessejamesdallas]

Doubt the radio is causing the high SWR Reading. (even tho the Cobra 18 is not the "Best" CB to start with) I would try a different antenna, or maybe change the coax...Lot's of times, the coax connectors maybe bad, and causing the SWR meter to peg over in the red (3.0+ SWR= Ground Short...usually)

You could have a bran New Coax, right out of the package, and it can have a bad connector...The way they throw those things together now days, and don't test them, it's very command to get one that has a connector that is grounding out.

[Kawasaki7410]

I got the radio for free so I have no compaints about that...
but my magnetic base for my antenna is hardwired on the end by the base so I would have to get a whole new base to fix that, which I don't really have the money for right now.
Tomorrow I'll try re wiring my ground and see if that helps.
My antenna seems to be working well because earlier this evening I was up on a hill (elevation of about 2500 ft) and was able to talk to a guy about 20 miles away, I was extremely suprized it was able to reach this far honestly honestly.

[jessejamesdallas]

I got the radio for free so I have no compaints about that...
but my magnetic base for my antenna is hardwired on the end by the base so I would have to get a whole new base to fix that, which I don't really have the money for right now.
Tomorrow I'll try re wiring my ground and see if that helps.
My antenna seems to be working well because earlier this evening I was up on a hill (elevation of about 2500 ft) and was able to talk to a guy about 20 miles away, I was extremely suprized it was able to reach this far honestly honestly.

You were able to talk 20 miles away, with a Cobra 18, and a cheap magnet mounted fiberglass antenna, and are worried that the antenna is not tuned in right? ...Dude...It don't get much better than that!

[Kawasaki7410]

well its not that im worried that its not tuned right, i read somewhere that if you dont tune it it can fry your cb but somehow sending heat back in through you coax cable...
but im pretty sure it had alot to do with the altitude that i was at because everywhere else around me is at about 300 ft and i was at roughly 2500 ft (thats just a guess though...) and i just looked it up and it was about 25 miles.....that really really surprises me with my setup....

[Kawasaki7410]

well I just rewired my ground and got a high swr reading again so does that mean it's my coax for sure?

[Red Warrior]

I have seen the wire inside these plastic antennas break. Try another antenna.

Not unusual to reach out 20 miles (or more) from a high altitude location. Remember CB is line-of-sight. If you can see it, you can talk to it. Has very little to do with how well your radio is tuned.

['Doc]

Just how are you rewiring your 'ground'?
- 'Doc

[jessejamesdallas]

I have seen the wire inside these plastic antennas break. Try another antenna.

Not unusual to reach out 20 miles (or more) from a high altitude location. Remember CB is line-of-sight. If you can see it, you can talk to it. Has very little to do with how well your radio is tuned.

"Line of sight?" Are you kidding? If that were the case, no one would be talking DX, and I can talk to guys 30-40+ miles away, but I can't see that far...And it has everything to do with "How well the radio is tuned, and the antenna..."

You can take a $500 radio, that has a poorly tuned antenna, and have someone with a $20 /30 year old 23 channel radio that has a perfectly tuned antenna, just walk right over you and make you sound like your on a 1/2-a-watt Walkie-Talkie...

[Red Warrior]

I have seen the wire inside these plastic antennas break. Try another antenna.

Not unusual to reach out 20 miles (or more) from a high altitude location. Remember CB is line-of-sight. If you can see it, you can talk to it. Has very little to do with how well your radio is tuned.

"Line of sight?" Are you kidding? If that were the case, no one would be talking DX, and I can talk to guys 30-40+ miles away, but I can't see that far...And it has everything to do with "How well the radio is tuned, and the antenna..."

You can take a $500 radio, that has a poorly tuned antenna, and have someone with a $20 /30 year old 23 channel radio that has a perfectly tuned antenna, just walk right over you and make you sound like your on a 1/2-a-watt Walkie-Talkie...

There are basically three ways a CB Radio can talk long distances. Line-of-sight, ground wave, and skip. If you are 50 miles away on top of Mt McKinley and I can see the top from my location, I can talk to you using a 1/2 watt walkie talkie. That is line-of-sight. If you are in a semi-truck 20 miles in front of me over the next hill, I can use a 500 watt linear to extend the range of the "ground wave" and you can hear me. If you have a similar setup we can talk to each other. If skip conditions are in and permit it, I can talk to Jamaica from Phoenix using a barefoot radio pushing 3 watts. If skip is in and you want to talk on 27.025, ask please and one of the Big Dawgs might let you (that is of course unless you are running 15Kw with a 26dB gain 7 element quad).

[jessejamesdallas]

I have seen the wire inside these plastic antennas break. Try another antenna.

Not unusual to reach out 20 miles (or more) from a high altitude location. Remember CB is line-of-sight. If you can see it, you can talk to it. Has very little to do with how well your radio is tuned.

"Line of sight?" Are you kidding? If that were the case, no one would be talking DX, and I can talk to guys 30-40+ miles away, but I can't see that far...And it has everything to do with "How well the radio is tuned, and the antenna..."

You can take a $500 radio, that has a poorly tuned antenna, and have someone with a $20 /30 year old 23 channel radio that has a perfectly tuned antenna, just walk right over you and make you sound like your on a 1/2-a-watt Walkie-Talkie...

There are basically three ways a CB Radio can talk long distances. Line-of-sight, ground wave, and skip. If you are 50 miles away on top of Mt McKinley and I can see the top from my location, I can talk to you using a 1/2 watt walkie talkie. That is line-of-sight. If you are in a semi-truck 20 miles in front of me over the next hill, I can use a 500 watt linear to extend the range of the "ground wave" and you can hear me. If you have a similar setup we can talk to each other. If skip conditions are in and permit it, I can talk to Jamaica from Phoenix using a barefoot radio pushing 3 watts. If skip is in and you want to talk on 27.025, ask please and one of the Big Dawgs might let you (that is of course unless you are running 15Kw with a 26dB gain 7 element quad).

OK...Let's not get carried away...there's just "so-far" a 1/2 a watt is going to go...

[Red Warrior]

I have seen the wire inside these plastic antennas break. Try another antenna.

Not unusual to reach out 20 miles (or more) from a high altitude location. Remember CB is line-of-sight. If you can see it, you can talk to it. Has very little to do with how well your radio is tuned.

"Line of sight?" Are you kidding? If that were the case, no one would be talking DX, and I can talk to guys 30-40+ miles away, but I can't see that far...And it has everything to do with "How well the radio is tuned, and the antenna..."

You can take a $500 radio, that has a poorly tuned antenna, and have someone with a $20 /30 year old 23 channel radio that has a perfectly tuned antenna, just walk right over you and make you sound like your on a 1/2-a-watt Walkie-Talkie...

There are basically three ways a CB Radio can talk long distances. Line-of-sight, ground wave, and skip. If you are 50 miles away on top of Mt McKinley and I can see the top from my location, I can talk to you using a 1/2 watt walkie talkie. That is line-of-sight. If you are in a semi-truck 20 miles in front of me over the next hill, I can use a 500 watt linear to extend the range of the "ground wave" and you can hear me. If you have a similar setup we can talk to each other. If skip conditions are in and permit it, I can talk to Jamaica from Phoenix using a barefoot radio pushing 3 watts. If skip is in and you want to talk on 27.025, ask please and one of the Big Dawgs might let you (that is of course unless you are running 15Kw with a 26dB gain 7 element quad).

OK...Let's not get carried away...there's just "so-far" a 1/2 a watt is going to go...

So there is no question that 3 watts can go 6000 miles but concern that 1/2 watt can go 50 miles?

[jessejamesdallas]

So there is no question that 3 watts can go 6000 miles but concern that 1/2 watt can go 50 miles?

In DX, Yep...3w's can go 6000 miles, with perfect conditions, and a very good, well tuned antenna...But a 1/2 watt Walkie Talkie is not going to get much further than a 1/2 mile at best...

Heck...I have talked to 4040, and Warlord in Cali with just 2w's from my Suburban here in Dallas before...But when you start talking about normal conditions, only way your going to get any kind of range like your talking about, is by 1st, having a very good well tuned antenna, and then some Power to lite it up!

[Kawasaki7410]

Just how are you rewiring your 'ground'?
- 'Doc

I had it wired to my mount for my cb. And this morning I rewired it to my negative terminal on my battery. Which didn't do anything at all.... I'm still getting a horrible buzzing noise everytime I turn my truck on and when ever I jiggle my keys in the ignition or go to put my seat belt on it buzzes also.

[Kawasaki7410]

I have seen the wire inside these plastic antennas break. Try another antenna.

Not unusual to reach out 20 miles (or more) from a high altitude location. Remember CB is line-of-sight. If you can see it, you can talk to it. Has very little to do with how well your radio is tuned.

Whenever I'm driving and I go over a bump I can sometimes hear a poping noise from up on my antenna could that be a broken wire? I thought it was just my magnetic mount.
I just went out and took my antenna off and was seeing if I could replicate the noise and it's in the antenna, I can't tell what it is though it only does it down by where it screws into the base

[Red Warrior]

So there is no question that 3 watts can go 6000 miles but concern that 1/2 watt can go 50 miles?

In DX, Yep...3w's can go 6000 miles, with perfect conditions, and a very good, well tuned antenna...But a 1/2 watt Walkie Talkie is not going to get much further than a 1/2 mile at best...

Heck...I have talked to 4040, and Warlord in Cali with just 2w's from my Suburban here in Dallas before...But when you start talking about normal conditions, only way your going to get any kind of range like your talking about, is by 1st, having a very good well tuned antenna, and then some Power to lite it up!

I just talked to Motormouthmaul an hour ago (local). I was 7 miles away from him and he was running 1/4 watt and putting a 7 on my "S"-meter. He was running his "Mauldulator" barefoot which only puts out 1/4 watt. I have talked to him in the same mode from the top of Suey Creek road which is close to 20 miles. His 1/4 watt is into a 5/8 wave antenna and I was mobile with a 102".

[jessejamesdallas]

So there is no question that 3 watts can go 6000 miles but concern that 1/2 watt can go 50 miles?

In DX, Yep...3w's can go 6000 miles, with perfect conditions, and a very good, well tuned antenna...But a 1/2 watt Walkie Talkie is not going to get much further than a 1/2 mile at best...

Heck...I have talked to 4040, and Warlord in Cali with just 2w's from my Suburban here in Dallas before...But when you start talking about normal conditions, only way your going to get any kind of range like your talking about, is by 1st, having a very good well tuned antenna, and then some Power to lite it up!

I just talked to Motormouthmaul an hour ago (local). I was 7 miles away from him and he was running 1/4 watt and putting a 7 on my "S"-meter. He was running his "Mauldulator" barefoot which only puts out 1/4 watt. I have talked to him in the same mode from the top of Suey Creek road which is close to 20 miles. His 1/4 watt is into a 5/8 wave antenna and I was mobile with a 102".

Yep...I have no problem believing that...I do it all the time...But your talking about radios with a 102" Whip and one with a 5/8 wave antenna. vs. a walkie talkie, that last I looked, only come with a 2' telescopic aluminum antenna, or some short 6" rubber duckie type antenna!

-sorry Kawasaki7410 for Hijacking your thread.

['Doc]

Sorry, I asked the question wrong. This is what I'm wondering about, "my antenna is hardwired on the end by the base". I think I just misunderstood what you were saying. You're saying that the coax goes into the thingy surrounding the magnet, right? If so, that's basically how they all are.
One thing that you'll find is that the definition of 'ground'/'grounding' can mean lots of different things to different people. It very seldom ever describes what's really happening, and is probably misunderstood by more people than do understand it.
Your power ground, the 12 DC ground for the radio, between the two ways you had it connected, would typically show no difference at all. Especially concerning SWR, which has nothing to do with things at that point.
That sticking up thingy on top of that mag-mount is only 'half' of your antenna. The 'other half' of that antenna is whatever metal that mag-mount is sitting on. Every piece of metal that's electrically connected to every other piece of metal that mag-mount is sitting on is part of that 'other half' of the antenna. That 'other half' of the antenna is connected to the radio via capacitive coupling between the 'metal' and the magnet plate(s) which is attached to the braid of the feed line. Are you confused yet? Hang on, it get's 'better'! That metal vehicle's body is also capacitively coupled to whatever that vehicle is sitting on, dirt, concrete, wood, grass, a fine wool carpet, whatever. So, that is also some variable part of your antenna. Ever heard a fairly sort of dramatic change in what you could here when driving over some kind of different road surface? Now you know 'part' of why that can happen. Got a 'ride' you can 'slam'? Do so and check SWR. Then stand it on it's tippy toes and check that SWR again. Bet'cha there's a difference. Not huge, but a difference.
Ain't this 'spit' fun??
- 'Doc

[Red Warrior]

Yep...I have no problem believing that...I do it all the time...But your talking about radios with a 102" Whip and one with a 5/8 wave antenna. vs. a walkie talkie, that last I looked, only come with a 2' telescopic aluminum antenna, or some short 6" rubber duckie type antenna!

-sorry Kawasaki7410 for Hijacking your thread. [/quote]
Yeah I'm sorry too but this is an interesting discussion....

If you look at this from a theoretical viewpoint use the following data:

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PTX: 1 watt (zero dB) (transmit power)
Frequency: 27.0 MHz
Distance: 120,000 meters (74 miles)
GTX:0 (transmit gain)
Grx: 0 (receive gain)

Prx:-103dB (receive power)

Since most receivers have a receive sensivity threshold of -115dB you subtract -103 from -115 and get -12 dB or about 2 "S"-units. Play with that calculator, double the TX power and see what happens.

Admittedly a rubber ducky probably has a net loss in gain versus the zero gain I estimated.

[Kawasaki7410]

Sorry, I asked the question wrong. This is what I'm wondering about, "my antenna is hardwired on the end by the base". I think I just misunderstood what you were saying. You're saying that the coax goes into the thingy surrounding the magnet, right? If so, that's basically how they all are.
One thing that you'll find is that the definition of 'ground'/'grounding' can mean lots of different things to different people. It very seldom ever describes what's really happening, and is probably misunderstood by more people than do understand it.
Your power ground, the 12 DC ground for the radio, between the two ways you had it connected, would typically show no difference at all. Especially concerning SWR, which has nothing to do with things at that point.
That sticking up thingy on top of that mag-mount is only 'half' of your antenna. The 'other half' of that antenna is whatever metal that mag-mount is sitting on. Every piece of metal that's electrically connected to every other piece of metal that mag-mount is sitting on is part of that 'other half' of the antenna. That 'other half' of the antenna is connected to the radio via capacitive coupling between the 'metal' and the magnet plate(s) which is attached to the braid of the feed line. Are you confused yet? Hang on, it get's 'better'! That metal vehicle's body is also capacitively coupled to whatever that vehicle is sitting on, dirt, concrete, wood, grass, a fine wool carpet, whatever. So, that is also some variable part of your antenna. Ever heard a fairly sort of dramatic change in what you could here when driving over some kind of different road surface? Now you know 'part' of why that can happen. Got a 'ride' you can 'slam'? Do so and check SWR. Then stand it on it's tippy toes and check that SWR again. Bet'cha there's a difference. Not huge, but a difference.
Ain't this 'spit' fun??
- 'Doc

actually you didnt confuse me at all, haha

can not tuning the antenna mess the cb up at all? i read on another site that if its not properly tuned it somehow turns the signal it is recieving into heat and feeds that back into the cb frying the insides....


so now im wondering, what is causing all the noise when ever i turn my truck on? i have a Bandit noise filter in between my battery and my cb, i thought this would help but its not doing anything at all...

would it help if i used some of those braided grounding strips and grounded my doors to my cab, my cab to the frame, my bed to the frame, ect.? i remember reading another thread somewhere on this site that talked about that...

[Kawasaki7410]

-sorry Kawasaki7410 for Hijacking your thread.

Yeah I'm sorry too but this is an interesting discussion....

i dont mind, i just want to get this figured out....
ive been messing with it for three+ weeks now trying to get it to where i can talk while im driving and get a good signal without getting this annoying ERRRRRRREEEEEERRERNT!!! sound whenever im driving....

['Doc]

"can not tuning the antenna mess the cb up at all? i read on another site that if its not properly tuned it somehow turns the signal it is recieving into heat and feeds that back into the cb frying the insides"

Sort of, but not really. That's way over simplified, and there are quite a few "but's" that go along with it. Yes, it's better if an antenna is tuned to match the rest of the system. The most common way of measuring that is by using an SWR meter. That will tell you how close the antenna's input impedance is to 50 ohms. That SWR meter doesn't/can't tell you anything about resonance. There are ways of measuring resonance, but it ain't with an SWR meter and the price goes up like you wouldn't believe. So what's the big deal with resonance? That deals with some stuff called reactances. That input impedance is composed of a resistance and any reactances present. It can mean that resistance isn't really 50 ohms, it just appears to be 50 ohms because there are combinations of reactances that when added to whatever resistance the thing happens to have makes it seem like 50 ohms to an SWR meter. That means that if the resistance is sort of close to whatever, and the reactances makes it appear to be what the radio want's to see. The radio isn't going to get too mad about it and do what it's supposed to do, send all the power it can to that antenna. Okay, what's wrong with that? The biggy is that reactances do not radiate anything, only resistance does. So, part of the power that ought to be radiated isn't, it get's reflected back down that coax in the form of a standing wave. As long as that standing wave doesn't get too big, it just isn't much of a biggy at all (a fairly low SWR). If that standing wave/SWR get's to be very big, that can be bad. That reflected power is composed of current and voltage. The current sort of turns into heat, the voltage can cause arcing. Those are the two big baddies with SWR. It's also an over simplification, so don't take it as pure gospel!



"so now im wondering, what is causing all the noise when ever i turn my truck on? i have a Bandit noise filter in between my battery and my cb, i thought this would help but its not doing anything at all..."

Basically, what it amounts to is that there's something that's running when the truck is that creates RF noise. Some noise filters work, some don't. I have no idea why your's isn't. There are two ways noise can get into a radio, through the power line, or through the antenna. Wait till you hear that noise, and disconnect the antenna. Did it go away? If so, then the noise is being radiated by something and isn't getting in through the power line. The ways to stop that from happening are to make it quit radiating, or by preventing that radiation from getting out where it can get to the antenna (keep it under the hood where it won't bother anything). That's where all that bonding of body parts together does pay off, it sort of 'encloses' that noise.
If the noise doesn't disappear when you disconnect the antenna, bet on the power line being the way into the radio. That's where those noise filters come in handy. Or where by-passing the power leads to the offending device is nice (capacitors/chokes). That's also one of the hardest things to do, because sometimes it ain't very easy finding those @#$ devices, or by-passing them. (The in-tank fuel pumps are notorious for that sort of thingy.) All car manufacturers are aware of the problem and have solutions for them. The only problem is getting the dealers to cough them up. Good luck with that!
- 'Doc

[Kawasaki7410]

"so now im wondering, what is causing all the noise when ever i turn my truck on? i have a Bandit noise filter in between my battery and my cb, i thought this would help but its not doing anything at all..."

Basically, what it amounts to is that there's something that's running when the truck is that creates RF noise. Some noise filters work, some don't. I have no idea why your's isn't. There are two ways noise can get into a radio, through the power line, or through the antenna. Wait till you hear that noise, and disconnect the antenna. Did it go away? If so, then the noise is being radiated by something and isn't getting in through the power line. The ways to stop that from happening are to make it quit radiating, or by preventing that radiation from getting out where it can get to the antenna (keep it under the hood where it won't bother anything). That's where all that bonding of body parts together does pay off, it sort of 'encloses' that noise.
If the noise doesn't disappear when you disconnect the antenna, bet on the power line being the way into the radio. That's where those noise filters come in handy. Or where by-passing the power leads to the offending device is nice (capacitors/chokes). That's also one of the hardest things to do, because sometimes it ain't very easy finding those @#$ devices, or by-passing them. (The in-tank fuel pumps are notorious for that sort of thingy.) All car manufacturers are aware of the problem and have solutions for them. The only problem is getting the dealers to cough them up. Good luck with that!
- 'Doc

yeah i took my antenna off and it stopped so i guess ill do all that body grounding sometime soon when i get more money, i really hope that it will fix it, ive been messing with this for over three weeks now....
do you know where i can get those braided grounding strips?

['Doc]

Braided ground straps aren't absolutely required. Copper flashing cut into strips will work fine too. A bit more non-flexible, but they work. Rather than buying those 'straps' I'd make them (cheap, you know). Got some old coax laying around? Skin the braid off of it and cut to suit. Tin the ends and screw'em on things. Bare copper in any form typically doesn't last too long around the stuff cars normally get on them, that's why I'd tin them. After that, it's just whatever you happen to have sort of. I wouldn't bother scrapping paint off things, star washers work just dandy. Get as elaborate/fancy as you want.
- 'Doc