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Can the swr be to low?

King Mudduck

King Mudduck

FEAR THE DUCK!
May 6, 2005
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285 South Western Virgina waving!
1st a little info.Cobra 148 gtl,4 pill box(375 peak watts) and a 102 steel whip with the really fat grey coax(dont no what is called but its really thick) swr less than 1 from ch 1 to 40.Matter of fact the needle hardly moves when i check my swr reading.
Today i had my wife drive my(p/u) truck down the road and talk to me so i could see how well my radio setup worked.She runs a Galaxy 95T in her car with a wilson 2000 trunk mount.I was VERY SHOCKED at how poorly it sounded.I mean it was clear and had a good sound to it but was nowhere near as loud as i thought it should be.So i want to know if your swr can be to low?I once heard from a cb tech that it is good to have a little swr,not real high but he said that somewhere between 1.2 to 1.9 was good(you know the things we hear from cb shop's r mostly B,S) So is there any truth in this or what?
Thanks for the help and happy dxing!
 

first of all, your swr is not less than 1. 1:1 is a perfect match and there is nothing lower. second of all, your swr has nothing to do with how loud your transmitter sounds. if your box is doing 375 is that carrier only or when the transmitter is modulated? if that is the power output with the transmitter modulated, how much power does the amp produce when keyed but unmodulated?
 
something is definatley not right there a 102 is not that broadbanded of an antenna it should be higher on both ends of the band. get an antenna anlyzer or try putting yout meter at the antenna end and recheck that swr. could be the length of coax your using is fooling your meter into seeing a swr reading that low at the radio end.

or if it is that good of a match maybe its just your radio needs to be retuned. turn off the amp see if it still sound the same.???

492 x (Velocity Factor) / Frequency (MHz) to get the right length of coax to get a real readiing at your radio.

so if your using rg8/u 492*.80/27.2050 =14.467 feet
that is for channel 20 middle of the 11 meter band it wont change but a couple inches on 40 and ch1 so just use the middle of the band length. look on the side of your coax for the exact type of coax you have then use the chart on this link to get the propper velocity factor for the formula.

http://www.freewebs.com/skunkworks/coax1.htm

here is a link that will explain what im talking

so its either the coax giving you a false reading or your radio need tuned up.
 
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Not so FLNative.....My whip on my pickup is under 2.0:1 from 24.900-28.500. CB band is flat as an arrow. Whips are fairly broadbanded
Buck
 
CDX197 said:
4 pill box(375 peak watts)
Click to expand...
:eek: what kind of amp is it? I am getting a 4 pill and im going to drive my 2 pill with it and it should give out close to 1000 watts. That just dont sound right if thats your swing out of a 4 pill!
Click to expand...

Your going to drive your 2 pill with your 4 pill? You can try that, but I don't think you will have much luck. Try using that 2 pill to drive that 4 pill. It might work better.
 
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Elkin Rg 8/u is whats on the coax and its 21 feet long.
My key with the box on is 60 watts swinging to 375.
i dont even know what kind of box it is as it has no name on it but i have had it for over 3 years and it has always worked well,maybe i should take my radio for a check up.
 
ok regardles of wr i would increase the carrier on radio to till you see about 90-95 watt carrier out of that box. wich would give you a 1 to 4 swing. wich is were you want to be. even though i run mine on am at 1 to 2 or 1 to 3.

375w/4 = 93.75watts
 
Do you need 21' of coax?? From amp to antenna??
If not go with less...1.2 for an swr is great...1.4 in my eyes max
but thats just me...(for normal purpouses)
What is the insulator material of that coax? Foam?
Ok..then find out the velocity factor of that coax...
Then do the equasion listed above for the length you need to run...
And get an ohm meter say like a DMM and check to exactly a 50 ohm reading...
Hope this helps:)

AM POWER
 
To answer the original question very simply, no, SWR can't be too low. It can be too high. And, an swr of something around 1.5:1 isn't a problem especially with the average 102" whip (in fact, it's pretty good).
It's not uncommon for an antenna to ~not~ be a 50 ohm load. A 102" whip is typically something around 25-30 ohms, so unless you do some impedance matching you will not see better than about 1.5:1, if that good. Is that a problem? No, it isn't, don't worry about it.
Can SWR make a radio sound like it's not supposed to? Well, if it's bad enough, it can make one sound sort of weak (less power getting to the antenna). But normally SWR doesn't change the 'sound' of a radio. I'd suggest looking else where for that kind of a problem.
- 'Doc

PS - For those worrying about the length of 50 ohm coax feeding an antenna, I'd also suggest you check the 'turn signal fluid' for proper levels...
 
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If you're putting out 350 watts and you still sound "weak" at fairly close range, I'd say check the mic first, and then the radio. Oh yeah, and don't forget the simple stuff, like making sure you don't have the mic gain too low.
 

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