CB Antennas
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08-17-2008
#22
Big John,
Don't let 'em get you down, just remember the definition of a "ham". It's half a hogs butt.
Been there too, had to deal with 'em when I was in the Navy maintaining AM and FM radios going both ways. BOL
Don't let 'em get you down, just remember the definition of a "ham". It's half a hogs butt.
Been there too, had to deal with 'em when I was in the Navy maintaining AM and FM radios going both ways. BOL
#23
Sealord, no one's getting mean down, I was just laughing because I asked a simple question and it went to this big debate. I like your definition of a Ham, that is funny. :lol:
#24
Quote:
I am confused there kc0iv, you say the impedance of a quarter wave antenna is 35 ohms, I run on my blazer a 102 stainless steel whip with 50 ohm rg-8m coax and have a 1.5 to 1 ratio on 3 bands, one above and below the cb band, if I ran 75 ohm coax the match would be off, I did this for several years and tried everything from 200 ohm down to 5 ohm wire and tested dual and quad harnesses with antron 99 base antennas, the 50 ohm is a standard wire for cb hook ups, running 75 ohm is generally used in a dual co-phase harness which has been developed over 35 years ago and has worked since then, I remember using 1/4 wave antennas that were non tunable witth 50 ohm coax and we used a capacitor on the feedpoint to get SWR to match if need be, this was before the pl259 was used, as for antetnna tuners, we used them on long wire antennas, I tuned a trash can and a car body to a piece of roofing, we also tried the train tracks but could not get them to match, we transmitted on lightbulbs to coat hangers so a matcher is great for this but not trucks, thats funny...
Well uglymutt It seems you didn't lean much when you studied for your ham ticket. So I'll give you a little learning.I am confused there kc0iv, you say the impedance of a quarter wave antenna is 35 ohms, I run on my blazer a 102 stainless steel whip with 50 ohm rg-8m coax and have a 1.5 to 1 ratio on 3 bands, one above and below the cb band, if I ran 75 ohm coax the match would be off, I did this for several years and tried everything from 200 ohm down to 5 ohm wire and tested dual and quad harnesses with antron 99 base antennas, the 50 ohm is a standard wire for cb hook ups, running 75 ohm is generally used in a dual co-phase harness which has been developed over 35 years ago and has worked since then, I remember using 1/4 wave antennas that were non tunable witth 50 ohm coax and we used a capacitor on the feedpoint to get SWR to match if need be, this was before the pl259 was used, as for antetnna tuners, we used them on long wire antennas, I tuned a trash can and a car body to a piece of roofing, we also tried the train tracks but could not get them to match, we transmitted on lightbulbs to coat hangers so a matcher is great for this but not trucks, thats funny...
A 1/4 wave antenna functions by using the vertical portion (the whip) against a ground plane of at least 1/2 wavelength. The feed impedance of a 1/2 wave antenna is 72 ohms. Quoting from http://www.radio-electronics.com/inf...e_vertical.php
Quote:
The voltage and current waveforms show that at the end the voltage rises to a maximum whereas the current falls to a minimum. Then at the base of the antenna at the feed point, the voltage is at a minimum and the current is at its maximum. This gives the antenna a low feed impedance. Typically this is around 20 ohms.
Losses in the surrounding area will raise this impedance to a value of around 30-35 ohms.The voltage and current waveforms show that at the end the voltage rises to a maximum whereas the current falls to a minimum. Then at the base of the antenna at the feed point, the voltage is at a minimum and the current is at its maximum. This gives the antenna a low feed impedance. Typically this is around 20 ohms.
I'd like to see the specs on these coax feed-lines. You must have one heck of a set up to be able to manufacture coax. Since they are not generally available.
You talk about the PL-259. I'm sure you are aware that the PL-259 and its' matching SO-239 are NOT constant impedance connectors.
Why would you think a matching circuit are not for truck? A matching network doesn't know if its connect to a truck or the side of a steel building. All it is concerned about is matching one impedance to another impedance. Another question. What is the difference between a long wire and a 5' whip other than length?
If you have created an antenna that will span a frequency spread of 2:1 or greater that can be feed by a 50 ohm coax with a lose equal to better than a 102" whip I'd like to see it and its' specs. No one else in the industry has been able to do it.
Quote:
I been a ham for 30 years and never heard what you are saying here, you got me confused, the reason why coax is 50-52 ohms is that way for a reason, I can buy a non tunable francis 5 foot whip and a 10 foot piece of 50 ohm rg 58 coax and a cheap cobra 19 radio and hook it up on the right mirror of a truck and get a 1.5 to 1 match on all 40 channels, why would i need a scope, we used them when testing dual and quad harnesses so its great if your a designer and developing antennas, a swr meter is just fine for the general setting of a 4 watt cb... where are you coming from with your reasons here, its not rocket science... we could discuss velocity factors and how to cut coax to proper length but thats all good for a commercial 100,000 watt station and we all know that the impedance in a coax cable is determined by the distance from the inner wire and the gap to the braid so by sharp bends or pinching the wire will change the ohms which will change the match, so there is no need for all this info for a simple setup, some people think too much and really its not a concern when you can just hook up a cb and go.... damn antenna tuners trying to get that 1.00001 to 1 ratio, you all crack me up..
To my way of thinking anyone that is in the business of setting up antenna needs an antenna scope. Why would you anything less? Might as well use the one mounted in most CBs. If you want to use a less costly approach would be an HF/VHF/UHF Antenna/SWR/RF Analyzer w/ LCD, Counter & Meters. MFJ makes a fine one for $379.95.I been a ham for 30 years and never heard what you are saying here, you got me confused, the reason why coax is 50-52 ohms is that way for a reason, I can buy a non tunable francis 5 foot whip and a 10 foot piece of 50 ohm rg 58 coax and a cheap cobra 19 radio and hook it up on the right mirror of a truck and get a 1.5 to 1 match on all 40 channels, why would i need a scope, we used them when testing dual and quad harnesses so its great if your a designer and developing antennas, a swr meter is just fine for the general setting of a 4 watt cb... where are you coming from with your reasons here, its not rocket science... we could discuss velocity factors and how to cut coax to proper length but thats all good for a commercial 100,000 watt station and we all know that the impedance in a coax cable is determined by the distance from the inner wire and the gap to the braid so by sharp bends or pinching the wire will change the ohms which will change the match, so there is no need for all this info for a simple setup, some people think too much and really its not a concern when you can just hook up a cb and go.... damn antenna tuners trying to get that 1.00001 to 1 ratio, you all crack me up..
I doubt that you want to discuss advance electronic. I am a EE and designed antennas for a living among other things. I retired from electronics and started driving a truck for a few years. Now I'm fully retired. BTW I've got time on you also. I was first licensed in 1958 ( been continually license since the '60) for what that's worth.
I have no problem with your concern about proper coax routing. I do disagree with you antenna placement. Much better to place it on the left side to reduce the chance of tree damage. As I said in my post "My suggestion. Mound a single antenna on the left side of the truck (protects the antenna from trees). Something in the range of 4' length. Base loaded. With a proper ground. Enough 50 ohm coax to reach from the antenna to the radio. Start using it. "
Quote:
What I said is not wrong at all, its just you have a different way of doing it, so I know you been a ham for 10,000 years and your god but the devil in me says your a fool for saying what you did... now I guess your not wrong because what you said can be done so can my advice which is meant for people who aren't godlike and have scopes and matchers to just hook up and play with a cb... better luck next time.
You can on here proclaiming yourself as some kind of expert. Yet you didn't even know the impedance of a 102" whip. What I said is not wrong at all, its just you have a different way of doing it, so I know you been a ham for 10,000 years and your god but the devil in me says your a fool for saying what you did... now I guess your not wrong because what you said can be done so can my advice which is meant for people who aren't godlike and have scopes and matchers to just hook up and play with a cb... better luck next time.
Remeber uglymutt it was YOU that brought up the myth thing. Trying to prove you had this great knowledge on antennas. Which will work fine most of the time. Yet, I've had time the VSWR showed a 1:1 yet the transmitter wouldn't load correctly. When I put the scope on it I found a large reactive component on the transmission line. Corrected the reactive component and it loaded just fine. As I said anyone doing this as a business should have the knowledge and the correct equipment. Same thing can be said about co-phasing systems. To set up such a system correctly takes more than a simple VSWR meter.
kc0iv
#25
ohhh kc0iv, I never said to place it on the right mirror, I just used that as an example that it would still work, antenna, coax and radio just hook up and go, its best for a single on the driver side for sure, but what i am getting at, most truck drivers are not going to spend $3000 dollars on setting up a radio to get a 1:1 match, a 4 watt radio is not worth it, I on the other hand would run a $700 dollar HF rig with a 100 wattt am output to drive a 2k amp and yes I would be using my $400 meter to set it up, I would run a co phased harness, with simple antennas , like the k40 trucker but I would also heat shrink all my connections and be using belden wire, belden has any ohm wire you can think of, I would use a double shielded coax witt gold plated ends, by the time I am done I would have $3000 dollars into it and spend about 15 hours in the middle of a 10 acre empty lot, most truck drivers just want a simple setup thats hook and go and for the most part it can be done really cheap and simple....
I am not trying to get down on ya, i been to many keydowns and seen several setups and know alot of hams that make there own quad beams and I have played with antenna theories for years and proved alot of myths, I have talked many miles on 1 watt in several bands and ran coax over 1000 feet once to measure line loss and done everything possible, I learned that even the weather can change you swr, one day its 1.4:1 then on a low presure day it 1.6;1 , and I learned that just driving by a building will change your swr and being close to a tree can change it, but I also learned that a 1.5:1 and a 1.2:1 ratio has no difference on the recieve end when hear from these two radios you will here them both the same and see no meter change but yet people try and try to cut coax to acheive a 1.2:1 and in reality it don't matter on a 4 watt radio or a 40 wattt.
we can discuss the s-meter and how to gain 1 s-unit take your rf power to double twice, example you run 4 watts and hit me at 4 s-units to get to 5 s-units its 4x2x2 or 16 watts now to get to 6 s-units on the meter then you would need 16x2x2 or 64 watts, so to gain 2 s units from 4 watts you need to put out 64, so 3 s-units is 64x2x2 is 256 watts and then 1024 watts to is 4 s-units... so from 4 to 8 on the meter took 1000+ watts, so now swr means something here, say a 3:1 is what uhhh 25 power loss, 25% of 4 watts is 1 so now you putt out 3 watts, wow but from a 1000 watts itts 250 watts lost, now it means something on the s-meter scale, I run alot at 2:1 on 100 watts or less because its not a big deal until you start a commercial station or run 2k+ like I like to then it can become an issue. for the simple trucker, just hook it up and if it reads below 2:1 on the swr scale your fine but 1.5:1 is a standard 4% loss of power, now thats for a simple hook up.... SWR is not bad and too many people think I have to have a 1:1 match or my radio will blow up... its not rocket science at 4 watts and the s-metter cannot see that small of a differnce at that low of a power on the rerceive end of another radio so ,maybe you might know somemore about all of this stuff ....please explain if you do and maybe why you would need 1:1 at 4 watts or if a 1.5:1 is okay , thnx...
I am not trying to get down on ya, i been to many keydowns and seen several setups and know alot of hams that make there own quad beams and I have played with antenna theories for years and proved alot of myths, I have talked many miles on 1 watt in several bands and ran coax over 1000 feet once to measure line loss and done everything possible, I learned that even the weather can change you swr, one day its 1.4:1 then on a low presure day it 1.6;1 , and I learned that just driving by a building will change your swr and being close to a tree can change it, but I also learned that a 1.5:1 and a 1.2:1 ratio has no difference on the recieve end when hear from these two radios you will here them both the same and see no meter change but yet people try and try to cut coax to acheive a 1.2:1 and in reality it don't matter on a 4 watt radio or a 40 wattt.
we can discuss the s-meter and how to gain 1 s-unit take your rf power to double twice, example you run 4 watts and hit me at 4 s-units to get to 5 s-units its 4x2x2 or 16 watts now to get to 6 s-units on the meter then you would need 16x2x2 or 64 watts, so to gain 2 s units from 4 watts you need to put out 64, so 3 s-units is 64x2x2 is 256 watts and then 1024 watts to is 4 s-units... so from 4 to 8 on the meter took 1000+ watts, so now swr means something here, say a 3:1 is what uhhh 25 power loss, 25% of 4 watts is 1 so now you putt out 3 watts, wow but from a 1000 watts itts 250 watts lost, now it means something on the s-meter scale, I run alot at 2:1 on 100 watts or less because its not a big deal until you start a commercial station or run 2k+ like I like to then it can become an issue. for the simple trucker, just hook it up and if it reads below 2:1 on the swr scale your fine but 1.5:1 is a standard 4% loss of power, now thats for a simple hook up.... SWR is not bad and too many people think I have to have a 1:1 match or my radio will blow up... its not rocket science at 4 watts and the s-metter cannot see that small of a differnce at that low of a power on the rerceive end of another radio so ,maybe you might know somemore about all of this stuff ....please explain if you do and maybe why you would need 1:1 at 4 watts or if a 1.5:1 is okay , thnx...
#26
Quote:
I am not trying to get down on ya, i been to many keydowns and seen several setups and know alot of hams that make there own quad beams and I have played with antenna theories for years and proved alot of myths, I have talked many miles on 1 watt in several bands and ran coax over 1000 feet once to measure line loss and done everything possible, I learned that even the weather can change you swr, one day its 1.4:1 then on a low presure day it 1.6;1 , and I learned that just driving by a building will change your swr and being close to a tree can change it, but I also learned that a 1.5:1 and a 1.2:1 ratio has no difference on the recieve end when hear from these two radios you will here them both the same and see no meter change but yet people try and try to cut coax to acheive a 1.2:1 and in reality it don't matter on a 4 watt radio or a 40 wattt.
we can discuss the s-meter and how to gain 1 s-unit take your rf power to double twice, example you run 4 watts and hit me at 4 s-units to get to 5 s-units its 4x2x2 or 16 watts now to get to 6 s-units on the meter then you would need 16x2x2 or 64 watts, so to gain 2 s units from 4 watts you need to put out 64, so 3 s-units is 64x2x2 is 256 watts and then 1024 watts to is 4 s-units... so from 4 to 8 on the meter took 1000+ watts, so now swr means something here, say a 3:1 is what uhhh 25 power loss, 25% of 4 watts is 1 so now you putt out 3 watts, wow but from a 1000 watts itts 250 watts lost, now it means something on the s-meter scale, I run alot at 2:1 on 100 watts or less because its not a big deal until you start a commercial station or run 2k+ like I like to then it can become an issue. for the simple trucker, just hook it up and if it reads below 2:1 on the swr scale your fine but 1.5:1 is a standard 4% loss of power, now thats for a simple hook up.... SWR is not bad and too many people think I have to have a 1:1 match or my radio will blow up... its not rocket science at 4 watts and the s-metter cannot see that small of a differnce at that low of a power on the rerceive end of another radio so ,maybe you might know somemore about all of this stuff ....please explain if you do and maybe why you would need 1:1 at 4 watts or if a 1.5:1 is okay , thnx...
Originally Posted by uglymutt
ohhh kc0iv, I never said to place it on the right mirror, I just used that as an example that it would still work, antenna, coax and radio just hook up and go, its best for a single on the driver side for sure, but what i am getting at, most truck drivers are not going to spend $3000 dollars on setting up a radio to get a 1:1 match, a 4 watt radio is not worth it, I on the other hand would run a $700 dollar HF rig with a 100 wattt am output to drive a 2k amp and yes I would be using my $400 meter to set it up, I would run a co phased harness, with simple antennas , like the k40 trucker but I would also heat shrink all my connections and be using belden wire, belden has any ohm wire you can think of, I would use a double shielded coax witt gold plated ends, by the time I am done I would have $3000 dollars into it and spend about 15 hours in the middle of a 10 acre empty lot, most truck drivers just want a simple setup thats hook and go and for the most part it can be done really cheap and simple....I am not trying to get down on ya, i been to many keydowns and seen several setups and know alot of hams that make there own quad beams and I have played with antenna theories for years and proved alot of myths, I have talked many miles on 1 watt in several bands and ran coax over 1000 feet once to measure line loss and done everything possible, I learned that even the weather can change you swr, one day its 1.4:1 then on a low presure day it 1.6;1 , and I learned that just driving by a building will change your swr and being close to a tree can change it, but I also learned that a 1.5:1 and a 1.2:1 ratio has no difference on the recieve end when hear from these two radios you will here them both the same and see no meter change but yet people try and try to cut coax to acheive a 1.2:1 and in reality it don't matter on a 4 watt radio or a 40 wattt.
we can discuss the s-meter and how to gain 1 s-unit take your rf power to double twice, example you run 4 watts and hit me at 4 s-units to get to 5 s-units its 4x2x2 or 16 watts now to get to 6 s-units on the meter then you would need 16x2x2 or 64 watts, so to gain 2 s units from 4 watts you need to put out 64, so 3 s-units is 64x2x2 is 256 watts and then 1024 watts to is 4 s-units... so from 4 to 8 on the meter took 1000+ watts, so now swr means something here, say a 3:1 is what uhhh 25 power loss, 25% of 4 watts is 1 so now you putt out 3 watts, wow but from a 1000 watts itts 250 watts lost, now it means something on the s-meter scale, I run alot at 2:1 on 100 watts or less because its not a big deal until you start a commercial station or run 2k+ like I like to then it can become an issue. for the simple trucker, just hook it up and if it reads below 2:1 on the swr scale your fine but 1.5:1 is a standard 4% loss of power, now thats for a simple hook up.... SWR is not bad and too many people think I have to have a 1:1 match or my radio will blow up... its not rocket science at 4 watts and the s-metter cannot see that small of a differnce at that low of a power on the rerceive end of another radio so ,maybe you might know somemore about all of this stuff ....please explain if you do and maybe why you would need 1:1 at 4 watts or if a 1.5:1 is okay , thnx...
Hey Mutt, don't talk too much about your setup, R Ray is still lurking in the wings, and you might get a tongue lashing about the amp...lol
#27
[quote="uglymutt"[/quote]
Since there are some on this forum don't seem to want to learn something I'll refrain from making any additional comments.
I will instead direct you to the website http://www.seed-solutions.com/gregor...MeterBlues.htm
which explains 'S' meters and why they can't be trusted to perform the test you suggest.
'73
kc0iv
Since there are some on this forum don't seem to want to learn something I'll refrain from making any additional comments.
I will instead direct you to the website http://www.seed-solutions.com/gregor...MeterBlues.htm
which explains 'S' meters and why they can't be trusted to perform the test you suggest.
'73
kc0iv
#28
Well yes to a big 10-4 kc0iv, lots of people are not into radiowaves like some people are.. the page your link too is good info, read it before, I was just using everyting I said as a general way of looking at the big picture.
To a general cb operator, a simple setup is just as good as it gets, hook up and go with a swr 2:1 or lower is safe to run and will not hurt , trying to acheive the maxium performance and gettting your 4 watt cb peaked is worthless in most applications. I know as well as others a 4 watt cb has a 5 watt final transistor and peaking it to say like 7 watts will only shorten the life of the radio..
I hear people all the time saying the cb doctor peaked thier cb to 7 watts and they are now the best cb on the road with there mod circuit clipped and the SWR down to 1.1:1.... I know I laugh when I hear this.... I can show them its all bogus but I hate to burst their bubblehead....
If you are just looking to be simple wittout having too pay alot and try tuning and all that, its safe to say just buy a non tunable antennna 4 feet or longer (any length is fine though) buy enough coax with connectors to reach the radio witout bending or pinching too much and your good.. mount antenna on driver side mirror with a good bracket ..... all this is so simple and it works just fine..... cost less than $100 bucks...
Radio - cobra 19 ultra, $40
Antenna - Francis 4 foot fibreglass, $25
Coax with connnectors premade say 10 foot or 12 foot long , $15
mirror mount , $10
see less than a 100 bucks, upgrade to a better radio like a cobra 29 or 25 (about $100 for radio) and its less than $150 and works just as good as the antenna tweakers with their peaked out radio.....
To a general cb operator, a simple setup is just as good as it gets, hook up and go with a swr 2:1 or lower is safe to run and will not hurt , trying to acheive the maxium performance and gettting your 4 watt cb peaked is worthless in most applications. I know as well as others a 4 watt cb has a 5 watt final transistor and peaking it to say like 7 watts will only shorten the life of the radio..
I hear people all the time saying the cb doctor peaked thier cb to 7 watts and they are now the best cb on the road with there mod circuit clipped and the SWR down to 1.1:1.... I know I laugh when I hear this.... I can show them its all bogus but I hate to burst their bubblehead....
If you are just looking to be simple wittout having too pay alot and try tuning and all that, its safe to say just buy a non tunable antennna 4 feet or longer (any length is fine though) buy enough coax with connectors to reach the radio witout bending or pinching too much and your good.. mount antenna on driver side mirror with a good bracket ..... all this is so simple and it works just fine..... cost less than $100 bucks...
Radio - cobra 19 ultra, $40
Antenna - Francis 4 foot fibreglass, $25
Coax with connnectors premade say 10 foot or 12 foot long , $15
mirror mount , $10
see less than a 100 bucks, upgrade to a better radio like a cobra 29 or 25 (about $100 for radio) and its less than $150 and works just as good as the antenna tweakers with their peaked out radio.....
#29
Quote:
Peaking a CB from 5 watts to 7 watts would amount to a gain of 0.14 dB. Not what I call a big gain. In the commercial world we never consider changing a transmitter with anything less than 10 times the increase of power. Just isn't worth the expense.Originally Posted by uglymutt
I hear people all the time saying the cb doctor peaked thier cb to 7 watts and they are now the best cb on the road
kc0iv
