Dont waste your time cophasing. get down to the nitty gritty. lol. Simple. Tune front to lowest SWR then move back. If you running steel whips, it only need the pot belly spring to get it to tune. the run a straight 102" whip on the front then your set.
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CB co-phased antennas
- Thread starter KF5FUR
- Start date
RatsoW8
Supporting Member, W9WDX ARC Member - WD8T
IMHO if co-phasing two antennas on a mobile installation yielded any discernible efficiency or gain improvement (mobile gain....lol) than running one antenna in the best configuration then every mobile ham radio enthusiast out there would be co-phasing mobile antennas. I've never seen this as a topic on a serious amateur antenna forum. It's just a gimmick. The mis-information about running dual mobile antennas sells more CB antennas and some people think it looks cool. I wouldn't waste my cash.
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Rw8 what are you talking about, been running co-phased screwdrivers for years. Tune them slightly out of phase and they work awesome. Best part is they only need to be 6" apart for best performance. Going to make a kit to sell on EBay, thinking about charging $1500 for the complete setup...... lol Yes RW8 I totally agree with you.
Yes but you can extend the harness with the 50 ohm cable. The end of the harness is 50 ohm. 2 x 50ohm antennas in parallel = 25 ohm the 75ohm cable is for impedance matching so at the end it's 50 ohm
Out of phase for end fire arrays require less spacing .Can get some front to back as well if you change the length of one antenna.
Just reread w9clls post LOL ..Phased arrays can be made to work but way out of the league of the average cber or foundation licence holder for that matter.
Just reread w9clls post LOL ..Phased arrays can be made to work but way out of the league of the average cber or foundation licence holder for that matter.
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Minigrass would love to test that setup with a field strength meter and a analyzer. At those spacings the feedpoint can't be anywhere near 50 ohm if the parasitic element is working . Of course you could detune the elements to get the swr right . Not saying it can't be made to work .Just might not be working as well as you think.
Thats a nice looking setup mini! a couple questions, 1 it seems popular alot of guys towards the south run a setup like that? is it predominantly rear directional?or, http://www.skater229.com/55antennamagic.html One in the front, one on the raer. Minimum of 6 ft apart. Get um up above the roof line. and a metal plate or square tubing connecting both antennas. One Hot(Front) one grounded(Rear). Hereʻs what I had. Hot antenna puck mounted through the roof, Reflector on camper shell. Ran flat bars under the shell the some chicken wires then grounded them to the truck bed via the widow frames.
Q 2 how dose it perform?
yes you can extend the phased lines with 50 ohm cable in theory it should work......due to each antenna having a 50 ohm impedence,,,,however i have never tried ths and it is also a 6$ per splice minimum to do this at the antenna end of system. therefor, i would recommend doing it at the line in side directly out of the signal source with a singular patch cord, vrs 2 of them at the antenna side......
Now when i say 6$ per splice im talking materials time and energy (soldering 2 coax ends adding a reducer, and installing a coupling)<which is also a rf , as well as moisture weak link! no no......if we could build coax assemblys out of couplings 90s and t's it would cost a arm and a leg, and take a crap load of time to assemble...keep is simple. 6$ can also = 40$ for a cold pl259 bad solder joint- in wasted time, if not done correctly! (my time is 28$ an hr). whats yours worth?
Im not bragging im just saying a bad solder joint, (sometimes happems due to stuff not being clean fluxed and tinned properly) <happens!
pl259- rg213 pl259-t-( 2 x reduced pl259 75 ohm cable pl259) -antenna mount -antenna. that is as simple as it gets
(if you want to add a 50 ohm "patch cord".<this is most simple way
Option 2 someone insits apon adding a "50 ohm patch chord on a phased circuit" one per circuit,,,,,,,,,i woud recommend doing such in wave lengths of 1/4 of the known res freq x velocity factor of coax. + also doing the same on the actual co phase harness.
in my own oppinion (not proven) this would be best place to start the expirement.
from there one could butch the whole setup to attempt to "do a scientific presentation".
my take on it is keep it simple- keep it clean . run a 102 and youll shoot on through!
Now when i say 6$ per splice im talking materials time and energy (soldering 2 coax ends adding a reducer, and installing a coupling)<which is also a rf , as well as moisture weak link! no no......if we could build coax assemblys out of couplings 90s and t's it would cost a arm and a leg, and take a crap load of time to assemble...keep is simple. 6$ can also = 40$ for a cold pl259 bad solder joint- in wasted time, if not done correctly! (my time is 28$ an hr). whats yours worth?
Im not bragging im just saying a bad solder joint, (sometimes happems due to stuff not being clean fluxed and tinned properly) <happens!
pl259- rg213 pl259-t-( 2 x reduced pl259 75 ohm cable pl259) -antenna mount -antenna. that is as simple as it gets
(if you want to add a 50 ohm "patch cord".<this is most simple way
Option 2 someone insits apon adding a "50 ohm patch chord on a phased circuit" one per circuit,,,,,,,,,i woud recommend doing such in wave lengths of 1/4 of the known res freq x velocity factor of coax. + also doing the same on the actual co phase harness.
in my own oppinion (not proven) this would be best place to start the expirement.
from there one could butch the whole setup to attempt to "do a scientific presentation".
my take on it is keep it simple- keep it clean . run a 102 and youll shoot on through!
also one last thought,,,,,,most transmitters (that i know of ) have a singular output. make use of this and feed a singular coax line- that can later t/ or y to ,,,2 antennas. on the way there for each ,,,,,,50 ohm antenna fed directly with 75 ohm cable.
mutiple un needed splices is bad workmanship, and possible source for un desired resistance/ leaks.
mutiple un needed splices is bad workmanship, and possible source for un desired resistance/ leaks.
The post states he has 19 ft runs and only 12ft cables on his harness !Agree on using one length of cable if possible , however if you have to extend with 50 ohm cable you can as long as both cables are the same length and yes in an ideal world they should be resonant 1/2 waves X the velocity factor of the cable .But as long as the antennas aren't highly reactive it will work.Nothing experimental about it it's done all the time . Back when I was doing this for a living I was being charged out at $80 an hour but what does that have to do with it? Don't get paid for this now so I guess my time now is not worth squat. I wouldn't recommend splicing unless you are very competent with a iron. Two patch cables with barrel connectors would be fine at 27 mhz. Of course he could just throw away a good phasing harness and buy a longer one.
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All forward my freind. 6feet minimum. the farther apart they are, the less signal out the rear and less receive from the rear.