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Mid-band SWR testing/tuning


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Posted

So when using a SWR meter what's your process??  Do you tune the radio mid-band to check SWRs??  Do you tune the radio to your preferred channel to check SWRs??  Do you check SWRs at the highest radio output power setting ??

If I were to "tune" SWRs to Channel(s) 20, 21 or 6 ; do I really need to check channels 15 and 14??

 

6 answers to this question

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Posted

It was alwasy common to test in the middle when we used CB and think GMRS would be the same. With that said repeaters are 467.xxx and simplex is 462. If you use simplex 99% of the time I'd test on a middle 462.xxx channel. For instance a 1/4 wave should work fine across the board. It realyl depends on useage. For my SAR stuff we always use the National SAR channel for tunign as thats the most important channel we use. Other channels are repeaters and a portable works fine so worring about a great single from the mobile is less concerning. Granted we are all in the VHF side and most folks run a quarter wave to eliminate then eed to tune to a certain frequency. 

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In my humble opinion, I tune my mobile antennas closer to 467, since I primarily use repeaters and I'd like to have maximum efficiency on the transmit end. If you only work simplex, tune it closer to the 462 end. But like they say about instruction manuals, that's just how one guy did it.

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Posted

I have found that my antennas get real good SWR on 462.XXX MHz or 467.XXX MHz but not both. I'll get 1.0 to 1.2 SWR on one and up to 1.8SWR on the other. Don't worry about it as long as your SWR is at 1.8 and below for both.

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Posted

From what little experience I have had, its like squeezing jello.  You can get a really good tight antenna that really works well for a specific freq, but then suffers outside that given frequency.  It kind of comes down to where you spend most of your time.  if 90% of your time is hitting repeaters, then tuning around 467 is a good thing.  Picking a different antenna can make a difference to.   A antenna with a "FLATTER" swr response, may not give the highest db, but may give a better overall performance.  Its to easy to fall into the "Analysis Paralysis" mode and overthink it.   SWR info is good, however little things can affect swr reading by a tenth or so.  So SWR numbers can really tell you which way the wind is blowing, but splitting hairs over a 1.2 versus 1.4 is great from academic discussion, but does not mean that much.  Its good info...  All info is good info.   regards.

462_467.jpg

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Posted

I’ve got too much going on in my life to worry about tuning antennas.  I get pretuned antennas and get over 200miles from a 20w base station.  Never have over 1.4swr on any gmrs frequency.   Even my little mag mounts on the trucks are 1.2-1.5 and do 50-60miles no issue.   

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Posted

Way too much is made of SWR below 2.0:1 (ref. power 11%) or even 2.5:1 (ref. power 18%).

Unless you have lossy cable the power ends up going out of the antenna anyway because that reflected power is reflected again at the radio and goes back to the antenna where the greatest portion goes into the antenna.
 

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