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619 NJ
05-21-2013, 04:44 PM
Getting ready to make jumpers. How long from radio to box and then how long from box to antenna?


619 the Chef choppin' lips and deep-frying Mud Ducks in the Yellin' Yukon and I'm gone...

High Voltage Mobile NJ
05-23-2013, 01:02 PM
dammmmmmm your going big , wowwwwww a driver box and a big box. cool. I use a 18 feet coax from the radio to the driver box. I used to use a 12. I feel in my case the 18 footer brought the reflect down slighty more between the radio and the driver box . 6 feet between your driver and your big box should be fine . some boxes require you to use a 9 footer . it all depends on how good your box is tuned . :300 (287):

619 NJ
05-23-2013, 01:04 PM
No just one box for now. Doughboy actually gave me the formula for the coax. 14.82 feet based on te velocity factor of the lmr400uf. My jumper from the radio to the back of the truck is made, and so is the antenna cable. I'm just about ready to go.


619 the Chef choppin' lips and deep-frying Mud Ducks in the Yellin' Yukon and I'm gone...

High Voltage Mobile NJ
05-23-2013, 10:28 PM
No just one box for now. Doughboy actually gave me the formula for the coax. 14.82 feet based on te velocity factor of the lmr400uf. My jumper from the radio to the back of the truck is made, and so is the antenna cable. I'm just about ready to go.


619 the Chef choppin' lips and deep-frying Mud Ducks in the Yellin' Yukon and I'm gone... there is no formula when your running from your radio to the driver box because every radio has a difference in line capacitance and every radio is tuned different to , especially if you have a variable from your radio. velocity formula is great from your last box in line to your antenna system . :second:

619 NJ
05-23-2013, 10:29 PM
Aaahhh ok gotcha! 4-10


619 the Chef choppin' lips and deep-frying Mud Ducks in the Yellin' Yukon and I'm gone...

JesseJamesDallas
05-23-2013, 10:31 PM
This may help.
http://highfields-arc.co.uk/constructors/olcalcs/coaxcalc.htm

the caveman
05-23-2013, 10:39 PM
Is there any preferences on coax length from the radio to an external swr meter that will be removed after use?

High Voltage Mobile NJ
05-23-2013, 11:38 PM
they say u are suppose to have at least 1/2 wave of coax between . sometimes 9 feet will work to .

Birdy
05-24-2013, 11:25 AM
This may help.
http://highfields-arc.co.uk/constructors/olcalcs/coaxcalc.htm

That's the best was to put it so people understand.

BOOTY MONSTER
05-24-2013, 11:45 AM
No just one box for now. Doughboy actually gave me the formula for the coax. 14.82 feet based on te velocity factor of the lmr400uf. My jumper from the radio to the back of the truck is made, and so is the antenna cable. I'm just about ready to go.


what DB is talking about is using a electrical half wavelength of coax ...... not to be confused with a physical half wavelength of coax . the middle of the CB band (27.205 MHz.) has a wavelength of 36.1798 ft (rounded off) . a physical half wavelength of coax will be half of that length (18.0849) .

the difference between a physical half wavelength of coax and a electrical half wavelength (and multiples of it) is the EHWL will duplicate the vswr so it's not skewed by a meter or analyzer if the antenna is not tuned to a perfect 50 ohms . the few feet of extra coax length is negligible loss wise when using decent coax ..... even 8x . heres a link with info explaining it in more detail than i care to type .


http://www.dx-antennas.com/Coax.htm

" (http://www.dx-antennas.com/Coax.htm) ........................ WHAT LENGTH?As mentioned the best length is the shortest, in this way the loss due to the cable is the lowest.
There can be one advantage by extending the length of the cable:.
A HALF WAVE coax cable or ANY multiple (1, 1, 2 wavelength) length of this will show you: "exactly the same input resistance at both ends of cable". In normal words:
You can measure the exact SWR from the antenna with these lengths of coax cable.If your antenna is truly 1:1 it doesn't matter, each SWR measurement anywhere on the line and you will find 1:1.
Only when your SWR isn't 1:1 but higher your measurements will change according to length, this is when it can come in handy to keep the line a half wave long (or any multiple). .................

............................. COAX AND VELOCITY FACTORThe shielding and the core of a coax form a capacitor. Through the use of insulation material, the value of the capacitor is bigger then it would be in air, and this has the effect of slowing down the signal. This can be of great importance in some applications, although for many purposes it does not needed this information ;-)Velocity factor
The speed at which the signal travels is normally given the abbreviation VF and this is the fraction of the speed at which the signal travels when compared to a signal traveling in free space. So VF for a signal traveling at the speed of light would be 1.0, and for one traveling at half the speed of light it would be 0.5.

The velocity factor of the coax cable is found by VF = 1 / SQRT (dielectric constant)Coax cable electrical length
One important factor of a coax cable in some applications is the wavelength of the signals traveling in it. In the same way that the wavelength of a signal is the speed of light divided by the frequency for free space, the same is also true in any other medium. As the speed of the wave has been reduced, so too is the wavelength reduced by the same factor. So if the velocity factor of the coax cable is 0,66, then the wavelength is 0,66 times the wavelength in free space. ......... "

High Voltage Mobile NJ
05-24-2013, 11:54 AM
what DB is talking about is using a electrical half wavelength of coax ...... not to be confused with a physical half wavelength of coax . the middle of the CB band (27.205 MHz.) has a wavelength of 36.1798 ft (rounded off) . a physical half wavelength of coax will be half of that length (18.0849) .

the difference between a physical half wavelength of coax and a electrical half wavelength (and multiples of it) is the EHWL will duplicate the vswr so it's not skewed by a meter or analyzer if the antenna is not tuned to a perfect 50 ohms . the few feet of extra coax length is negligible loss wise when using decent coax ..... even 8x . heres a link with info explaining it in more detail than i care to type .


http://www.dx-antennas.com/Coax.htm

" (http://www.dx-antennas.com/Coax.htm) ........................ WHAT LENGTH?As mentioned the best length is the shortest, in this way the loss due to the cable is the lowest.
There can be one advantage by extending the length of the cable:.
A HALF WAVE coax cable or ANY multiple (1, 1, 2 wavelength) length of this will show you: "exactly the same input resistance at both ends of cable". In normal words:
You can measure the exact SWR from the antenna with these lengths of coax cable.If your antenna is truly 1:1 it doesn't matter, each SWR measurement anywhere on the line and you will find 1:1.
Only when your SWR isn't 1:1 but higher your measurements will change according to length, this is when it can come in handy to keep the line a half wave long (or any multiple). .................

............................. COAX AND VELOCITY FACTORThe shielding and the core of a coax form a capacitor. Through the use of insulation material, the value of the capacitor is bigger then it would be in air, and this has the effect of slowing down the signal. This can be of great importance in some applications, although for many purposes it does not needed this information ;-)Velocity factor
The speed at which the signal travels is normally given the abbreviation VF and this is the fraction of the speed at which the signal travels when compared to a signal traveling in free space. So VF for a signal traveling at the speed of light would be 1.0, and for one traveling at half the speed of light it would be 0.5.

The velocity factor of the coax cable is found by VF = 1 / SQRT (dielectric constant)Coax cable electrical length
One important factor of a coax cable in some applications is the wavelength of the signals traveling in it. In the same way that the wavelength of a signal is the speed of light divided by the frequency for free space, the same is also true in any other medium. As the speed of the wave has been reduced, so too is the wavelength reduced by the same factor. So if the velocity factor of the coax cable is 0,66, then the wavelength is 0,66 times the wavelength in free space. ......... " I beg the differ 8x is garbage and using better coax makes a hell of a difference . stop believing everything you read booty . iv'e got friends in here right now can tell you after they changed that 8x junk they had better performance on the transmit and receive side . it makes a big difference . velocity factor this . bump bump :300 (209)::welcome:

BOOTY MONSTER
05-24-2013, 11:57 AM
differ all you want ... no need to beg . on 27 MHz. for 100 ft or less the loss is negligible , if you're not running more power than tha the coax can handle . having the pl-259's correctly attached is very important !

as for your friends ...... get some smarter ones :300 (241):

High Voltage Mobile NJ
05-24-2013, 11:59 AM
OPTIMAL LENGTH BETWEEN LINEAR / ANTENNA / TRANCEIVER ??
There are stories about the length between an amplifier and the antenna/ transceiver. The above goes for this as well.
Just keep it as short as possible, there is no benefit to make it anything else . this is so untrue what you posted booty !!!!!!!!!!!

BOOTY MONSTER
05-24-2013, 12:05 PM
LOL , read the article in context ......
you may need this first though .

https://www.hookedonphonics.com/

High Voltage Mobile NJ
05-24-2013, 01:17 PM
this post has turned into toolbag.com :300 (121):

619 NJ
05-24-2013, 01:18 PM
Why is it every time I ask a question it devolves in to trolling chaos? Ugh.


619 the Chef choppin' lips and deep-frying Mud Ducks in the Yellin' Yukon and I'm gone...

BOOTY MONSTER
05-24-2013, 03:19 PM
i hate when that happens

High Voltage Mobile NJ
05-24-2013, 09:38 PM
Why is it every time I ask a question it devolves in to trolling chaos? Ugh.


619 the Chef choppin' lips and deep-frying Mud Ducks in the Yellin' Yukon and I'm gone... sorry 619 . booty loves copying and pasting and don't know crap . iv'e down all these tests and use the proper lengths to do so . booty just cant take a good answer with some real facts . he want to argue and argue . :300 (73):

619 NJ
05-24-2013, 09:40 PM
It's ok bro. I get my truck tomorrow! Probably going to drill it this weekend! Gonna need a fine tune next time you are around, if you don't mind. :)


619 the Chef choppin' lips and deep-frying Mud Ducks in the Yellin' Yukon and I'm gone...

BOOTY MONSTER
05-25-2013, 12:18 PM
i explain the what and why about what DB told you and you wanna accuse me of trolling your thread . :300 (236):

i'll try to keep in mind how unappreciative you are and not help your silly butt anymore .
take care :)

619 NJ
05-26-2013, 08:25 PM
No I didn't accuse YOU of trolling. I'm having a laugh because the past few times I've asked a question, it has turned in to a pissing match between people. It's not you in particular.


619 the Chef choppin' lips and deep-frying Mud Ducks in the Yellin' Yukon and I'm gone...