Correct way to swr a SSB

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108EH002
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Re: Correct way to swr a SSB

Post by 108EH002 » 03 Jun 2018, 00:40

Using an Imax with no insulation between the Imax and 14 ft pole that sits on t and k brackets.The Imax/827/SGM are all different designs but none were ever insulated from the pole it was being connected to.When I had the SGM I was going to isolate it from the pole because it was a dipole,but just connected metal to metal.
Maybe the SGM might have been closer to the Imax/827 tx/rx instead of being 1 signal point down if it had been insulated.
None of the local mates who are amateurs have said to insulate antenna from pole being connected to,sure the one with the MM0 callsign would have mentioned it as he has owned an 827/Imax and uses a SGM at present ;)
You can talk worldwide on CB radio = not 10 - 15 miles,
rsgb are too far up their own @rses to admit it = snobs.

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wa10
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Re: Correct way to swr a SSB

Post by wa10 » 03 Jun 2018, 16:56

108EH002
in our multiple tests the gainmaster had a small advantage over the 827 & imax,
it is the best performing white stick i ever compared to other antennas, within needlewidths of my interceptor i10k & much broader vswr bandwith,

my new imax was way behind under the conditions we tested, probably due to lack of radials & decoupling from the mast & coax allowing common mode to spoil the pattern as w8ji tells us, in other tests we have done the imax was much closer to the gainmaster

our tests were done with nothing close to the base of the antennas,

the people that i have seen post the opposite results usually have the antenna close to buidings etc,
ihmo but i can't prove it the gainmaster does not like anything near the base of the antenna, short pole on chimney or gable end is not a place i would put a gainmaster.

i would avoid gainmasters if you intend running upwards of 200w on FM.

108EH002
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Re: Correct way to swr a SSB

Post by 108EH002 » 03 Jun 2018, 20:16

The antenna height is 28ft off the ground at present but have read the SGM likes plenty clearance to work properly.Have been thinking about changing the pole for a 20ft one,but thats as far as it has got.Thanks for sharing the info of your various antenna test results wa10 :thumbup:
You can talk worldwide on CB radio = not 10 - 15 miles,
rsgb are too far up their own @rses to admit it = snobs.

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Re: Correct way to swr a SSB

Post by Transwarp » 04 Jun 2018, 17:45

(down the mike) PEEEEEEEEEEEEP! AAAAAALOOOOOOOOHAAAAAAAAA ONE, ONE, ONE, EEEEEEEEEEEEEE-ARRRRRRRR!

Perfect swr on SSB :lol:
"Did video really kill the radio star?"

wa10
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Re: Correct way to swr a SSB

Post by wa10 » 04 Jun 2018, 21:03

Give it a go 108, higher & more in the clear the better for local work

i think w8ji explains why no radial endfeds like imax & a99 have some people swearing they are great and others just swearing at them due to noise or rfi issues or seemingly poorer performance,
he gives us a worst case scenario to make his point where cmc on the mast ( or coax ) significantly spoils the antennas pattern, talks about lucky lengths,

Does luck really play a part in how well no radial endfeds work for you ?.
imho yes it does because while you can measure the length of the coax outer braid the electrical length to ground through equipment often multiple paths of differing lengths is anybody's guess & that determines the common mode impedance & magnitude of cmc on the coax,

the same applies to masts, you can make a good length into a bad length & vise-versa by connecting it to ground or disconnecting it from ground depending on its electrical length,

i have seen improvements in signal and noise and BIG reductions in rfi by isolating a99 & imax from conductive masts, adding radials & choking the coax WHEN the user had an issue to start with,

imax or other no radial 5/8 tend to be worse for cmc than 1/2waves because they have more current at the base of the antenna than 1/2waves,

current maxima & maximum radiation is always 1/4wave from the tip of none loaded verticals & that's where a 5/8 gets its small advantage,
current maxima is 1/8wave higher above ground & obstructions, raise the 1/2wave to the same tip height and the 1/2wave has a slight advantage in low angle gain,

models from smarter guys than me & my own tests tell me a well installed or lucky a99 at the same tip height as a sirio gpe5/8 & 2000 series performs about the same,

i don't doubt the a99 & imax fishing rod haters own experiences as i have also seen the same thing in friends installs & my own tests, and i like many others have come to the wrong conclusions on why i was seeing what i was,

w8ji explains why a choke will not work if there is nowhere else such as radials for return currents to flow,

you can also cause issues by adding a choke when you had no issue to start with if you are unlucky enough for the choke to resonate the coax outer braid,
same thing with ground rods, they can reduce cmc on the mast or coax, they can also increase it depending on the electrical length of the mast/coax & ground wire,

i hope you can see why to isolate or not, to ground or not is a can of worms with no simple answer,

Do you feel lucky.

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Re: Correct way to swr a SSB

Post by 108EH002 » 04 Jun 2018, 21:48

I took the earth that runs to the ground rod off the Imax about 3 month ago,and re-connected it again at teatime today with some spare RG213 that was connected onto the bottom t and k as I had tried it connected onto the bottom bracket of the Imax before ,it does lower the received white noise as I think the fact that the antenna is on t and k brackets (not touching at ground level) but hard to tell if using it earthed is better/worse for local/dx in each different installation.The rest of the U.K. has been booming in for the last 5 hours and still is,with 26 div booming in on UKFM as I type.

Trial and error and a touch of just being lucky maybe.
You can talk worldwide on CB radio = not 10 - 15 miles,
rsgb are too far up their own @rses to admit it = snobs.

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Re: Correct way to swr a SSB

Post by wa10 » 04 Jun 2018, 22:00

you should have bought a lottery ticket at teatime :lol:

108EH002
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Re: Correct way to swr a SSB

Post by 108EH002 » 04 Jun 2018, 22:10

Odds of winning UK lottery about 14 million to 1,odds of me mucking about/experimenting 50/50 as it might improve but might be worse.....glad I earthed my antenna again as local noise at night is brutal......but sitting far lower now ;)
You can talk worldwide on CB radio = not 10 - 15 miles,
rsgb are too far up their own @rses to admit it = snobs.

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Re: Correct way to swr a SSB

Post by wa10 » 04 Jun 2018, 22:51

You got lucky, it could have gone the other way, did you do a before & after signal check with a reliable buddy or just looking at the noise level ?

Been playing with the software ch25 posted tweaking coax length in mm to find 1/2wave & 1/4wave with different loads,
10x the resolution of my analyser & 1000x + the resolution of a typical vswr meter .

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Re: Correct way to swr a SSB

Post by 108EH002 » 05 Jun 2018, 00:39

Before and after tests,no one noticed much difference only really the width of a needle to one local 10 mile away and flickering the next light on some lcd meters compared to my usual signal,only really earthed antenna to lower noise,as the tx signal is fine with the B300PS ;)
You can talk worldwide on CB radio = not 10 - 15 miles,
rsgb are too far up their own @rses to admit it = snobs.

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wa10
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Re: Correct way to swr a SSB

Post by wa10 » 05 Jun 2018, 09:59

A needlewidth & flashing the next bar is a change, if you get less noise too you got lucky,

i have used my multimeters connected across the s-meter or backing the rf gain down on unidens to put the signal close to the knee of the diode feeding the s-meter to exaggerate small changes in signal,,

when you see many needlewidths change or s-points between antennas its very likely other factors like cmc or height of current maxima over earth & obstructions or signals close to the knee of the diode that is making most of the difference on the meter.

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Re: Correct way to swr a SSB

Post by 108EH002 » 10 Jun 2018, 00:22

Lucky = experimenting with materials not supplied in the new antenna box like earth wires/groundplane radials that can maybe change the performance of a vertical CB antenna for the better.

" I wonder what will happen to my antenna if I try this " = if you choose the wrong way to enhance your
antenna,it could just be the fact you are actually thick as mince = that's unlucky.

It must be frustrating for some of the intelligent radio user's that some IQ0's are good at being lucky eh.
You can talk worldwide on CB radio = not 10 - 15 miles,
rsgb are too far up their own @rses to admit it = snobs.

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Re: Correct way to swr a SSB

Post by wa10 » 10 Jun 2018, 12:34

Experimenting is what radio is all about to me, i have cured multiple peoples rfi/cmc issues, made unusable imax & a99's into useable decent performers with no lip biting processor killing rfi,

having owned & compared most of the best cb antennas available since the mid 70's,
for many years i believed that a good 5/8 beats a starduster m400 & m800 or astroplane, a sigma4 beats any 5/8, an old style vector tuned correctly beats everything apart from a BIG-MAC,

when cb forums came about i met folk making claims about a99's been total **** fishing rods, i wanted to know why peoples results were so variable,

with the help of smart folk with software and many more comparison tests i now realize that my old tests were drawing me to the wrong conclusions, it made me buy antennas to test again that i had previously believed as not so good,

some people make blanket statements such as adding radials lowers the takeoff angle, others will tell you they tried radials and saw no change,
they can both be correct and both be wrong,

i have a local friend right now taking his new imax down because he is sick of it, says its ****, a static monster, he hates it, others love them,
it depends on how bad your cmc was to start with, it boils down to w8ji's lucky lengths & height of current maxima,

how many people would believe that when both are correctly installed an inexpensive starduster or dipole at the same tip height can have more low angle gain than any 5/8 or .64wave even the most expensive ones, or that a 1/2wave j-pole on the same mast should have an advantage over the most costly superdooper 5/8waves,

who would believe that an a99 at the same tip height as a sirio 2012 has about the same performance,

most of the differences in cb vertical antenna performance is due to other factors like cmc & height of current maxima not that one is a 1/2wave or any other wave, & yes luck plays its part.

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Re: Correct way to swr a SSB

Post by 108EH002 » 10 Jun 2018, 13:42

^^ What he said ^^
You can talk worldwide on CB radio = not 10 - 15 miles,
rsgb are too far up their own @rses to admit it = snobs.

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Re: Correct way to swr a SSB

Post by spyder3 » 12 Jun 2018, 18:07

What mode should I used whilst swr of the radio is undertaken: FM

Where is best to start in frequencies to swr: Close to your favorite frequency.

Should I swr the antenna with radio output power set at lowest level first: Yes. Usually 5-10 watts

Should I use the radios built in meter: No. Not accurate.

Use my known to be accurate cb swr meter I can put inline: You can put Inline your favorite SWR as DAIWA, Kenwood etc if it can handled the transmitting FM power. In SSB it’s useless, nobody measured SWR in SSB mode. Also if you put linear between SWR meter and antenna you cannot get correct measurements. That’s not covered in this topic. You do not need to know why at this point.

If their is anything I having considered please advise me so I may do things correctly please:
Build a chart Frequency / SWR to see your antenna limit. That’s protect you of burning your radio or linear if you jump too high or too low.
If cable between radio and antenna is very long the best place to put SWR meter is closer to aerial not to your transmitter
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