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Swr vs ohms

Conner, my old radio mentor from back in late 1960, a retired Army Master Sargent that spent most of his Army career teaching communications use to always remind me the same thing you are commenting on here.

Thanks for the excellent advice.
 
phantom309 said:
View attachment 18890 View attachment 18891 View attachment 18892

Ok, real life. This is the readings of my setup in my semi.

Sirio performer 5000 antenna, on a factory antenna stud, and factory coax, I am talking on a galaxy 99v2.

I am not allowed to change the coax cable or stud per company regulations.

The analyzer is extremely touchy to dial in a frequency but I got it as close to ch 1 ch 19 and ch 40 as it would allow me to go without going insane.

Looking at the pictures what should I do if anything?
Click to expand...

I would leave your setup alone 309.

If I understand any of this business...what you may have here is a condition the happens due to a feed line being included in the mix of your antenna system. So, if you could check your antenna setup at the feed point, and it was setup correctly or close, we might expect to see about 36 ohms at resonance...just like M0GVZ is suggesting.

And if you don't, then you will see some feed point transformation and instead...the results you are getting.

Either way you are close, not perfect, but close...and that is probably what matters.

I say all the time: We're just lucky that Mother Nature doesn't require our antenna systems to be perfect in order to work our radio.
 
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Marconi said:
I would leave your setup alone 309.

If I understand any of this business...what you may have here is a condition the happens due to a feed line being included in the mix of your antenna system. So, if you could check your antenna setup at the feed point, and it was setup correctly or close, we might expect to see about 36 ohms at resonance...just like M0GVZ is suggesting.

And if you don't, then you will see some feed point transformation and instead...the results you are getting.

Either way you are close, not perfect, but close...and that is probably what matters.

I say all the time: We're just lucky that Mother Nature doesn't require our antenna systems to be perfect in order to work our radio.
Click to expand...


Thank you marconi, I was surprised to see it set as well as it did.
 
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phantom309 said:
Thank you marconi, I was surprised to see it set as well as it did.
Click to expand...
It looks good to me too, even though it is not perfect...it is close.

Just remember you are using a feed line which can create a whole new set of worms according to what many claim is a very similar setup to yours, but they report a totally different and sometimes terrible results.

I have asked myself this question for years...how does this happen?

When I build an Eznec model of my 1/4 wave Marconi 4x and a 102" whip and a 3 x 102" radials, a suitable ground plane attached that looks like a starduster,
I see the following PDF kind of setup below:

It is noted in the PDF what this SWR bandwidth curve looks like at the end of a 68.5' run of .76 VF RG8U coax. My SWR meter, noted on the report, shows a low 1.10:1 SWR...just a little bit above 0 on the meter, but this is not a mobile setup.

However, if I had done this test using my VA1 at the feed point, I would expect maybe my match still might not show perfect, but through the feed line it is as good as it gets. So feed line and its length matters...when we talk about being perfect. Notice the very good bandwidth too.

309 to me, having a perfect match is about like what you see on your setup, and I say you are good to go.
 

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Beetle said:
Nothing you do is going to make any difference detectable on the other end of the QSO. It might change some of the numbers, but as long as you're keeping within that span of frequencies you're good to go.

You reached the point of diminishing returns a lot earlier.
Click to expand...


Actually I got lucky, put antenna on, trimmed twice and was done. Took less then 5 minutes total.
 
I got a buddy coming over with a mfj analyzer tomorrow.
What am I shooting for?
lowest X at 50ohms and 1.1?I'd like to test right at the base on the imax, get the best reading at say 27.350 with the rings and thats it? just throw on the coax and I'm good?

This is the best? (pretend it says 27.355)

2015002.jpg
 
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357 said:
I got a buddy coming over with a mfj analyzer tomorrow.
What am I shooting for?
lowest X at 50ohms and 1.1?I'd like to test right at the base on the imax, get the best reading at say 27.350 with the rings and thats it? just throw on the coax and I'm good?
Click to expand...

357, If you can reach the base of the Imax at installed height, would be the best results, but if you have to lower the antenna to reach the feed point...you might see a bit/a lot of change in the match.

IMO, I don't think you will see much difference, but I'm waiting for your report.

I checked a .625 wave with 4 x 104" horizontal radials at 36' feet and the match
64.98 Ohms resistance -259 Ohms reactance, with SWR = 22.664

At 12' feet the match was
70.86 Ohms resistance -263 Ohms reactance with SWR = 21.616

BTW my model did not include a matching device. Not much difference here, but you mileage may vary.
 
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phantom309 said:
View attachment 18890 View attachment 18891 View attachment 18892

Ok, real life. This is the readings of my setup in my semi.

Sirio performer 5000 antenna, on a factory antenna stud, and factory coax, I am talking on a galaxy 99v2.

I am not allowed to change the coax cable or stud per company regulations.

The analyzer is extremely touchy to dial in a frequency but I got it as close to ch 1 ch 19 and ch 40 as it would allow me to go without going insane.

Looking at the pictures what should I do if anything?
Click to expand...
phantom309 said:
View attachment 18890 View attachment 18891 View attachment 18892

Ok, real life. This is the readings of my setup in my semi.

Sirio performer 5000 antenna, on a factory antenna stud, and factory coax, I am talking on a galaxy 99v2.

I am not allowed to change the coax cable or stud per company regulations.

The analyzer is extremely touchy to dial in a frequency but I got it as close to ch 1 ch 19 and ch 40 as it would allow me to go without going insane.

Looking at the pictures what should I do if anything?
Click to expand...
 
go take a pill man !! I took my sirio out of the box put it together and had almost identical numbers ... best talking antenna I have ever owned .. swr stays way good from ch1 to ch42.. don't look a gift horse in the mouth ... go forth and play !! 73's XXX
 
Some antennas are harder to tune than others and every install is different. Get X to 0 and then work on the impedance and VSWR. Like Marconi said, use the analyzer at the feedpoint or as close to it as possible for best results. A 12" or shorter coax jumper or really directly connect to the feedpoint is your best bet. And don't worry so mkch about the VSWR as long as it's not bad. Get X to 0 and R to or as close to 50 as possible like the reading above you posted. You might not get a perfect VSWR, it won't make a difference if you get the other numbers right. 1.0-1.5 VSWR reading will be just fine. Take your time and also have as many hands to help you as possible!! And be safe. Stay away from any power lines!!! Good luck and again, just take your time. JMHO's!!
 
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Beetle said:
Nothing you do is going to make any difference detectable on the other end of the QSO. It might change some of the numbers, but as long as you're keeping within that span of frequencies you're good to go.
Click to expand...

Just a warning that given than he's managed to show X=0 then you're right but if you are just measuring the SWR, a 1:1 doesn't mean its working well and it could be working very bad compared to what it should. Its easy to demonstrate a poor RF ground using a lightbulb.

Get a table lamp and disconnect the neutral wire from the mains plug. Plug the light in, turn it on. You'll see it still lights up but with a very dim light. An antenna with a poor RF ground is the radio equivalent of this light. Unfortunately you can still achieve 1:1 with such a set up but as the light bulb only glows dimly your transmitted signal will also be weaker than it should and so will received signals. Because people manage to make contacts on setups with poor RF grounds as far as they're concerned it works.
 
222DBFL said:
Some antennas are harder to tune than others and every install is different. Get X to 0 and then work on the impedance and VSWR. Like Marconi said, use the analyzer at the feedpoint or as close to it as possible for best results. A 12" or shorter coax jumper or really directly connect to the feedpoint is your best bet. And don't worry so mkch about the VSWR as long as it's not bad. Get X to 0 and R to or as close to 50 as possible like the reading above you posted. You might not get a perfect VSWR, it won't make a difference if you get the other numbers right. 1.0-1.5 VSWR reading will be just fine. Take your time and also have as many hands to help you as possible!! And be safe. Stay away from any power lines!!! Good luck and again, just take your time. JMHO's!!
Click to expand...
222DBFL said:
Some antennas are harder to tune than others and every install is different. Get X to 0 and then work on the impedance and VSWR. Like Marconi said, use the analyzer at the feedpoint or as close to it as possible for best results. A 12" or shorter coax jumper or really directly connect to the feedpoint is your best bet. And don't worry so mkch about the VSWR as long as it's not bad. Get X to 0 and R to or as close to 50 as possible like the reading above you posted. You might not get a perfect VSWR, it won't make a difference if you get the other numbers right. 1.0-1.5 VSWR reading will be just fine. Take your time and also have as many hands to help you as possible!! And be safe. Stay away from any power lines!!! Good luck and again, just take your time. JMHO's!!
Click to expand...
so ch 19 or 27.185 mhz is the center of the cb universe.. that is as we all know approx. 36.2 feet without splitting rfch ...your 12 foot preference is a multiple of that .. most antennas tend to stay with 18 foot leads as we all also know .. any multiple 36 feet is better than hacking of a willie nille hunk of coax to tailor the fit to the given installation is not as tidy as a cut to fit pieces but sho nuff adjusts a lot better ..I myself prefer to deal in .5 wave lengths and fine tune with 1- 3 foot jumpers as well as stinger length.. trial and error. the swr's are good. finals tend to last along time and installs talk very well ..JMHO .. XXX
 

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