CB and antenna adjustment question

[Coalsmoke]

some of cobra's cb's like the 29 model have the SWR Calibration. Is this an important feature to have? Also, is SWR the same thing as those tunable antennas?



Thanks CB guru's

 

[bighammer]

The SWR calibration allows adjustment of the antenna length. Without it, you should buy or borrow a separate SWR meter for best performance.

 

[yogibear]

The SWR meters in the radio's are not very accurate, its best to use an external meter. SWR=standing wave ratio, the lower the swr, the better your radio will transmit & receive,the tunable ant. are able to adjust this. A good way to adjust swr is to check the swr on ch. #1, then check on ch. #40, if the swr is higher on 40, its too long, shorten the ant. , if its higher on #1, its too short, lengthen the ant. , when you get it pretty even, both high & low, it should be pretty flat on ch. #20. If you have a real high reading on both ends, you usually have a short, or bad connection somewhere. The lower the reading the better. Hope this helps.



Larry

 

[Coalsmoke]

so I would be able to do this with a clssic cobra 25 (which doesn't have the SWR calibration knob) and an adjustable antenna, or would the SWR Cal. be needed like on he 29 model? (Sorry, still a bit confused about which is recommended).

 

[Gary - K7GLD]

A separate SWR meter, connected as close to the base of the antenna as possible to eliminate stray problems from feedlines and such, is the best way to match the *antenna*...



Ideally, if all else is OK, once the best match is obtained at the base of the antenna, another SWR reading taken at the rear of the radio SHOULD be the same, or very close to it.



But what happens a lot of times, is that if there are irregularities throughout the system, bad feedline, fittings, etc. , a reading taken ONLY at the radio, either with it's own internal SWR meter, or even an outboard one at the rear of the set MIGHT be giving you a false indication of what is really happening in your antenna system - start at the base of the antenna for SWR, and work your way back to the radio itself...



THAT'S why the guys say you're better off with a separate SWR meter - at least for initial system setup = after that, an internal SWR meter is fine for spot checks to see if any changes have occured...

 

[Coalsmoke]

OK, so I could just buy a SWR meter and use it with an adjustable firestik and a Cobra 25, instead of getting the 29 with the SWR adjuster built in. Right?

If I got all this straight : WOOHOO and thanks for your help!

 

[bmoeller]

Yep, you got it.