Calgary Jeep Association

Author Topic: SWR Meter  (Read 2286 times)

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Offline Fredduck

  • That CB Yapper
  • Posts: 607
  • RIDE ON
Re: SWR Meter
« Reply #15 on: June 30, 2009, 08:29:46 PM »
If SWR is higher on 40 than 1, then antenna is too long, if SWR is higher on 1 than 40, then antenna is too short.  Or tune for lowest SWR on the most used frequency(Channel), 10 for club, 9 for emergency, 19 for typical trucker calling blah blah blah :)

In my experience, adding a spring to the mount effectively lengthens the antenna.

I want to carry out some experiments, as I've been taught as a CB person years ago that cable length mattered, as a HAM, I'm taught by the vast majority that it doesn't matter, but then came across a very technical, lucid article that explained that in an IDEAL setup with perfectly matched antenna, coax and transmitter it doesn't matter, but since this is real-world and they seldom perfectly match, it can make a difference (technical details left out).

I plan to do some experiments  ,  with cable lengths to see what I come up with "real-world".
I used a 12 foot cable and a 4 foot 5/8 firestick.
The size of the meter on the unit isn't great.
What difference in SWR between channel 1 and 40  matters?
3.9 CTD - 7000R4  NP241c SSYE, Dana 44.  9 inch, 4.10's  and 37's

Offline w squared

  • Talks waaay too much!
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  • Keamy Hungry!
Re: SWR Meter
« Reply #16 on: June 30, 2009, 08:58:26 PM »
Using the same antenna (tuned the same) your SWR will be a little bit different on each channel. This is due to the fact that each channel is a different frequency (and thus a different wavelength). As the wavelength changes with respect to the length of the antenna, the SWR will change.

Clear as mud, right?
I followed a rainbow out to a garage and found a leprichaun. The rainbow ended in a potted cactus on his porch, but there was no gold :(

Offline Fredduck

  • That CB Yapper
  • Posts: 607
  • RIDE ON
Re: SWR Meter
« Reply #17 on: July 01, 2009, 06:33:19 PM »
I DID IT...I DID IT...I DID IT

I left home and stayed in a HOLIDAY INN EXPRESS last night,
then I re-read the instructions and tuned my own antenna.

DUB-squared, thats for the offer and all the support.
3.9 CTD - 7000R4  NP241c SSYE, Dana 44.  9 inch, 4.10's  and 37's