Question about Cobra 148 GTL 120-Channels Base CB Radio
Hi Benimur, the only reason I chimed in on this topic is that years ago my CB shop did some testing on that antenna and a few others from Workman using a MFJ 269 analyzer. I seem to remember there being a coax chart available for CB freq's and also 10 meter freq's. There is no tuning adjustment on the ant itself, so there has to be some way for adjustments,, thanks, Mechanic
Posted on Feb 07, 2008
It would seem that you posted twice. Here is the link to your other post.
If I may add to Mechanic688, sharcnet, chiaflub67 and Nitrotrike's postings (with their indulgence), below is a copy of my reply to the other post....
"I read through the specifications of this antenna and you were right in posting "no ground plane, no tune". Still, there are only three (3) possible reasons why the SWR would be high:
1. Cable/connector - loose, cold solder or improperly terminated;
2. Antenna - tuning and/or ground plane; and
3. Radio has been highly modified or defect in final stage.
Corrective procedures would call for:
a. verify that the coaxial cable is properly connected to the PL-259 connectors. You may need to use a continuity tester (or a DVM) to do so. Pls pay particular attention to the braided shield/grounding, they should be real tight/soldered good to the casing of the connector. Of course the cable should be 50ohms RG8 or 58 with thick shielding.
b. as stated, the antenna doesn't need to be tuned then there's nothing that can be done since there is no provision for such, however, even if the specs says no ground plane needed, there is something you can try. Install a ground plane. this could be done by attaching 2 lengths of big gauge ordinary wire to both sides of the metal bracket of the antenna. They have to be 8' 7" ~ 9' long. It may help you further to install a grounding strap again from the metal bracket to any grounded metal portions of your house such as the plumbing.
c. radio problem would be unlikely if it is still stock."
Posted on Feb 07, 2008
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Posted on Jan 02, 2017
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