How to "tune" CB?

[Blkdawdg]

Can any of you CB gurus tell me what is the best way to tune my CB? My SWR's suck! I have a Cobra 29NWS. TIA

 

[B.G. Smith]

SWR

Can't help you with the tuning of the radio but if you want to set the SWR for the best reception/broadcasting: Check swr at channel 1 then channel 40. If the swr is highest on 1, the antenni is too long, if the swr is highest on 40 the antenni is too short. Adjust the antenni length slowly in about 1/8" increments until it is the same on 1 and 40. It will then be at its lowest in the center of the channels (20). bg

 

[Blkdawdg]

Then what is the SWR supposed to be at? I can use the SWR CAL knob to change it... . but what is the optimal place for it to be?

 

[Whitmore]

SWR (standard wave ratio) about the best you can get it is 1 to 1. 5 any good cb store can help you with this tuning ... ... ... ..... Kevin





the swr cal nob will not adjust your ratio, the way to use this is to key the mic and use the cal nob to set it at the top of the scale (it will show you on the display) then with the mic still keyed flip the switch back to swr and that will be your actual ratio

 

[JPittman]

Best ratio is 1:1, but anthing below 3:1 will work, it's not just as good. I might be misunderstanding you but you don't use the CAL to tune the antenna. You make the adjustment on the antenna then use the meter to see the ratio.



As in the previous post check channel 1 & 40. Since I am usually on channel 17 or 19 I tune the antenna for these and the lower and higher channels "fall into place. "



If you need a full set of instructions, I can fax them to you, email me your fax number. The instructions are for a Cal Comm meter. They use "FWD" for calibration and "REF" to see the ratio.

 

[Deezul1]

Go here for lotsa info on tuning and other stuff



http://www.firestik.com/

 

[ETOBICOKE]

SWR

SWR is the ratio of the transmitted power to the reflected power. The higher the ratio, the more of your signal power that is being wasted. Personaly I would never go over 1. 5:1, at 3:1 half of your transmit power is being wasted. The most common problem that causes high SWR is bad grounding at the antenna mounting, this must be a very good connection to the chassis of the vehicle, remember with most types of mobil antennas the chassis works as the ground plane, in effect the other half of the antenna system. You may also have to ground the body pannel that the antenna is attached to, to the chassis. The next most common problem is poor connections on the coaxial cable terminations, also if water gets into the end of the cable, you will have problems too. In some cases the body style of the vehicle and the mounting location of the antenna will affect the SWR, this can only be solved by moving the antenna to another location. Also when you check your SWR, try to replicate normaly operating conditions as much as possible. If you tune your antenna with the doors open and the truck parked beside your house you will never get a consistant reading.

The type of SWR meter that you use is also important, the cheap type that has to be adjusted to read the forward voltage and then switched over to read swr is a waste of time. If you can get the loan of a Bird Thruline Wattmeter or a cross needle type meter such as a Daiwa. Also note the Bird meter, because it measures wattage can be placed at either the transmitter or antenna end of the system, most other meters have to be placed at the antenna end to give the best readings.



Neil

 

[baby.driver]

My K-40 mag mount planted smack in the middle of the roof gives me a 1:1



Jay

 

[Blkdawdg]

Thanks!

Thanks for the help guys. I'm totally ignorant about this kind of stuff.

 

[ETOBICOKE]

Smoke from Texas

Blkdawg, judgeing from all the smoke you Texas boys are blowing to us up here in Canada, you should be able to find someone nearby that can help you out.



Neil

9SF915