testing out base antenna question?

[ocean pond]

I have a amtron 99 that I wanted to test/set SWR's on and have a problem that hopefully someone can help me out with. Strapped it to a pole and connected coax to my SWR meter and was getting 4's and even 6's depending on channels 1 to 40 citizens band. I have no ground attached to antenna or pole at this time. Also I may note that I checked all coax with a dummy load and checks out ok with test radio used.

[mopar2ya]

I have a amtron 99 that I wanted to test/set SWR's on and have a problem that hopefully someone can help me out with. Strapped it to a pole and connected coax to my SWR meter and was getting 4's and even 6's depending on channels 1 to 40 citizens band. I have no ground attached to antenna or pole at this time. Also I may note that I checked all coax with a dummy load and checks out ok with test radio used.

This may be an arguable topic. It is debated regularly. I will give you my opinion.

The first problem you need to address is common mode current on the feed line. A common mode choke made out of coax will eliminate this problem. This can be made by winding coax around a form and taping it in place or using ferrite beads on the outside of the coax. Either method creates a 1:1 transmission line transformer that will help to eliminate common mode currents that 'f with SWR meters. One way to -test- for this problem is to grab your coax or meter while transmitting. -Most- of the time, if you have a common mode current problem, grabbing either one will cause the meter reading to change. Sometimes it is drastic, and other times it is slight. Either way, any change by grabbing coax or meter indicates that you have this problem which should be corrected.

Secondly you need to create the other half of your antenna. This is quite a heavily debated topic, especially in the CB community. A 1/2 λ antenna needs a radial system to properly operate. It has been estimated that without the image plane as much as 75% of exciter power is lost to the earth. This system can be made in two ways. You can ground mount the antenna and use as many radials as you can muster (commercial stations use 120) or, you can elevate the system and use 4 or 8 tuned radials for a good result.

Incidentally, most of the first problem will be eliminated by solving the second problem.


Mopar

wan•na•boo (wah-nah-boo) Informal n. Derived of wan-na-bee 1. One who aspires to be a
Peakaboo. 2. One who imitates the behavior, customs, or dress of a Peakaboo. 3. A product
designed to imitate the qualities or characteristics of something built by a Peakaboo.
-.. --- -. - / ..-. --- .-. --. . - / - --- / -.. .-. .. -. -.- / -.-- --- ..- .-. / --- ...- .- .-.. - .. -. . / .-.-.- / .-.-.

[ocean pond]

Appreciate any help thanks guy! I have a ground plane kit but not installed yet. Maybe I'll try installing it on the bottom and then check SWR's again. Another question, is there a minimum height(from antenna base to ground) for tuning purposes?

[mopar2ya]

Appreciate any help thanks guy! I have a ground plane kit but not installed yet. Maybe I'll try installing it on the bottom and then check SWR's again. Another question, is there a minimum height(from antenna base to ground) for tuning purposes?

Nope. You can ground mount the antenna if you wish. But, if you are going to elevate the antenna, the higher you can conveniently get the antenna to tune it before you raise it, the more accurate the tune will be. I would try and get it at least 8' off the ground if I were you.

Mopar

wan•na•boo (wah-nah-boo) Informal n. Derived of wan-na-bee 1. One who aspires to be a
Peakaboo. 2. One who imitates the behavior, customs, or dress of a Peakaboo. 3. A product
designed to imitate the qualities or characteristics of something built by a Peakaboo.
-.. --- -. - / ..-. --- .-. --. . - / - --- / -.. .-. .. -. -.- / -.-- --- ..- .-. / --- ...- .- .-.. - .. -. . / .-.-.- / .-.-.

[hippieman556]

how good is that 99 antenna working for you