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Rastus, please add this to the tech section.
Setting the VSWR:
Some facts and pointers:
As the frequency of operation increases the radio wave gets shorter so a 1/4 wave antenna at CB frequencies is nominally 108"
As you have noticed the are plenty of 2', 3', 4' and 5' "top loaded" fiberglass antennas on the market. The manufacturer simply winds or loads the top of the antenna with the magnet wire so you still have 108" of antenna it has just been shortened. Now for you fellow electrical engineers out there I know this is oversimplified but the readers here do not want a bunch of technocrap, man we have too much of it here just explaining the basics, lol.
So on to setting the VSWR or tuning the antenna.
1st and this does need to be mentioned once again, CUTTING THE COAX to tune VSWR is not acceptable, you only are fooling the wattmeter by giving it a false reading of the forward to reverse voltage it should be measuring.
Hook up the wattmeter to the antenna and radio and tune the CB to ch. 40 and take a reading then go to ch. 1 and take a reading. If the VSWR is higher on ch. 40 than on ch. 1 then the antenna is too long so loosen the tip and slide it in some, not much go SLOWLY. If you have the type of commercial antenna where you cut some off the bottom then do so at the rate of 1/4" at a time. Repeat the measurement process till you have the best match on both ch. 40 and ch. 1 If the VSWR was higher on ch 1 you will have to slide the tunable tip out.
So what if you have slid the tip out as far as is possible and the VSWR is still very high on ch. 1 and high but not as high on ch. 40? this shows that the antenna is still a little short so try using a spring which will lengthen the antenna and also give you extra flex.
If you have done all the above and VSWR is still way high then you need to see if you have shorted the connector , easy to do, make sure you trimmed the braid neatly no single strand toughing the center conductor, even the tiny single strand can short the coax. If this was not the problem then you need to check the entire run of coax for a nick or see if it has gotten against the exhaust pipe and melted? I have seen some instances of just plain bad coax from a manufacturer. My recommendation is always use Belden or Tram or Andrew heliax brand coax, they are very high quality.
Happy Trails
Mark
Setting the VSWR:
Some facts and pointers:
As the frequency of operation increases the radio wave gets shorter so a 1/4 wave antenna at CB frequencies is nominally 108"
As you have noticed the are plenty of 2', 3', 4' and 5' "top loaded" fiberglass antennas on the market. The manufacturer simply winds or loads the top of the antenna with the magnet wire so you still have 108" of antenna it has just been shortened. Now for you fellow electrical engineers out there I know this is oversimplified but the readers here do not want a bunch of technocrap, man we have too much of it here just explaining the basics, lol.
So on to setting the VSWR or tuning the antenna.
1st and this does need to be mentioned once again, CUTTING THE COAX to tune VSWR is not acceptable, you only are fooling the wattmeter by giving it a false reading of the forward to reverse voltage it should be measuring.
Hook up the wattmeter to the antenna and radio and tune the CB to ch. 40 and take a reading then go to ch. 1 and take a reading. If the VSWR is higher on ch. 40 than on ch. 1 then the antenna is too long so loosen the tip and slide it in some, not much go SLOWLY. If you have the type of commercial antenna where you cut some off the bottom then do so at the rate of 1/4" at a time. Repeat the measurement process till you have the best match on both ch. 40 and ch. 1 If the VSWR was higher on ch 1 you will have to slide the tunable tip out.
So what if you have slid the tip out as far as is possible and the VSWR is still very high on ch. 1 and high but not as high on ch. 40? this shows that the antenna is still a little short so try using a spring which will lengthen the antenna and also give you extra flex.
If you have done all the above and VSWR is still way high then you need to see if you have shorted the connector , easy to do, make sure you trimmed the braid neatly no single strand toughing the center conductor, even the tiny single strand can short the coax. If this was not the problem then you need to check the entire run of coax for a nick or see if it has gotten against the exhaust pipe and melted? I have seen some instances of just plain bad coax from a manufacturer. My recommendation is always use Belden or Tram or Andrew heliax brand coax, they are very high quality.
Happy Trails
Mark
I've been usin' 1 for years. of course I expect my 2 ways to do better than a mile or so. I run a 19LTD ( slightly adjusted) with a wilson 1000 and the matcher. the erp is basically 20w and with the whip style I ain't skeered of trees! The tin roof at the sonic is another story.
