SWR, help me decode...

[earthbrown]

All done with trailer and in an empty parking lot, last night.


ch1 not showing up on meter or right at "1"

ch19 or ch20 "1.3"

ch40 "1.7-1.8"



Is this normal and acceptable?


K

[earthbrown]

and if good numbers can be achieved on an antenna is there a reason to get a different or "better" antenna, basically I am asking, is swr an indication of performance or simply the tuning...?

Like can same or good swr on 2 different antennas give you different range?



K

[Redneck]

Originally Posted by earthbrown

All done with trailer and in an empty parking lot, last night.


ch1 not showing up on meter or right at "1"

ch19 or ch20 "1.3"

ch40 "1.7-1.8"



Is this normal and acceptable?


K

Yes this is good....leave it alone.

[Redneck]

Originally Posted by earthbrown

and if good numbers can be achieved on an antenna is there a reason to get a different or "better" antenna, basically I am asking, is swr an indication of performance or simply the tuning...?

Like can same or good swr on 2 different antennas give you different range?



K

Some antennas will out do other antennas. I will get out of kc0rey's way and let him explain the differences in the antennas. Although he has explained it before in one of these threads.
But the SWR reading you have listed is exceptable..

[kc0rey]

The SWR listed will not burn up your radio. It does indicate that your antenna needs trimmed a little. Anything under 2:1 is fine.

A low SWR does not indicate the efficiency of your antenna. A Dummy Load (used for TX alignment and tune up) has a perfect SWR, yet it will not talk across the street.

What antenna are you using now? Brand, length, and type of truck and mounting position please.

[earthbrown]

05 Volvo 670

53 Foot Reefers


I am using the standard fiberglass antenna, HOWEVER, after I purchased the SWR meter, I was having trouble getting it tuned in.... readings were inconsistant, and spiked, I was in a vacant lot, nothing around me for 1/4 mile.





so I purchaced a good quality 18foot coax, and hooked it to the stock drivers side antenna, so now I am on a single antenna system, spent like 10-15 min adjusting the wires on the antenna and got it decently dialed in....


I think range is still a problem, I believe I am only getting like 2miles MAX, However, last night I talked to a person with a base CB for like 20 min as I drove across VT15, he said he was up on a hill, and told me the name of his town, which was about 5miles north of my road. I think this range had more to do with his ability to recieve and transmit.

IDK, I will wait to further mess with this antenna untill I find another place that caries the 5foot firestik..


I can fit 5foot, is there a benifit over the 4ft??? or is the 5 ft overkill?

I also heard that unless antennas are 9.5 feet apart 1 is better than 2 is this true?

K

[kc0rey]

Get the longest antenna you can run without hitting bridges. The longer the better.

The base you talked too had a huge advantage. That being hieght. His antenna was higher andthen he was on a hill so elavation really helped him.

Co-phasing or as we call it stacking is a tricky thing.

1. The antennas must be at least 1/4 wave apart.
2. The coax to each antenna should be 75 Ohm (TV Coax) and must be odd muliples of 1/4 wave in length. This will give you 50 Ohms at the radio.

1/4 wave = slightly more then 102 inches

1 piece of coax 1/4 wave length long can be slightly more or less than 102 inches long depending on Velocity Factor. Good RG-59 should have around a .66 velocity factor. 1 piece is an odd multiple but it has to be very close.

As I am sure you've surmised this is tricky.

Npw stacking the antennas will give you a gain of about 3dBi. The problem here is you are stacking omnidirectional antennas and your counterpoise (ground plane) will affect this allot.

So, it is my belief that yes, we can make it better with 2 antennas but the results certainly are not worth the effort.

Hopefully I have not confused you.

[earthbrown]

confused as hell....

Is a firestik 5ft and 18ft of coax, a good start?

I have to mesure now that I am home for the day BUT the 5ft firestick should work...

I have also seen these 4 ft cobras, they are fiberglass with an adjustable whip.....

And do you know if the francis are any good, they dont seem to be tunable....which makes me leary of buying one only to find a 3+ swr reading....


K

[kc0rey]

The Firestik 5 footer will work fine for you. If the coax is any good, 18 feet will work fine, but would not be my first choice. Run what ya' have.

I did not mean to confuse you.

The Francis ANtennas work well if you have 18 feet of coax. They are matched with a capacitor to maintain 50 Ohm impedance. and that is fine. They will not outperform the Firestik though.

Francis antennas are tunable. You just have to know how. If they are too short you buy a metal extention and if they are too long you use a hacksaw to trim them 1/8 of an inch until you are spot on. 99% of the time they dont need tuned.

[earthbrown]

Well after a 2 week search for a 5foot firestik, I settled for a 4foot.

Installed, tested and adjusted SWR on a back road, free from obstructions.

CH1, does not show up on meter.

CH19 reads 1.1

Ch40 Reads 1.5


Do i leave it alone or keep trying....


Cobra 25, 18ft coax, single 4ft Firestik.


K