Why is my SWR always changing????

[07dodgeram5.9]

It was poor contact through the trunk lid hinges. Somehow the lock was providing enough pressure to alter the stress on the hinges and make poor contact. As soon as the lid was popped up even just enough to clear the lock things went good. It would have bee MUCH easier to find if it was the other way around. LOL

Yea dvm on ohm setting would probably work pretty well on diagnosing that issue next time I would think one lead to your mount mechanism and other lead to good chassis ground/ battery negative

That is all in theory of mine

 

[07dodgeram5.9]

are you using an external swr meter? and i know this is crazy but had to deal with a newbie over it,,, he complained that one day it would quiet and he would turn volume up and said then it would blare and he would have to turn it down,,,,turned out it was just going from nonskip conditions to skip condition,, he didnt understand it yet,,,,

Lol yea I have a cheap $40 swr/power meter workman I know it's not the best but it works well as far as I can tell

 

[midnight special]

antenna ground and battery ground is 2 diferent things,,,,,, is the radio grounded?,,, check by unhooking coax if radio goes off the battery ground is coming back thru coax,,,,, could be your problem,,,,,, way to check is hook radio up to power no coax if it powers up you have battery ground,,,, now take contiuity meter and on coax unhooked from radio check for continuity from the collar of pl259 to ground ,,if you have continuity then that is good that means you antenna ground is not coming from radio but the antenna mount ground,,, i have seen many radio/antenna problems come up just from antenna not properly grounded and radio not grounded,,,,,

 

[Captain Kilowatt]

Yea dvm on ohm setting would probably work pretty well on diagnosing that issue next time I would think one lead to your mount mechanism and other lead to good chassis ground/ battery negative

That is all in theory of mine

Not nearly as simple as that. DC resistance is one thing and what may look good on an ohm meter may be totally unacceptable to RF. My Triplett 630-PLK meter got a workout that day for sure. Analog meters are far better for searching issues like that than digital meters. I have both. I have been into radio for about 38 years and worked in the broadcast industry doing service work for 22 years and that was the first time I ever saw something as odd as that. Guys I talked to said the same thing and everyone thought it should have worked better with the trunk down as the figured it would have a better ground thru the lock but this was just the opposite.

 

[Road Squawker]

... it would have a better ground thru the lock but this was just the opposite.

the lock mechanism latch has a sliding contact, just like door hinges. the contact is erratic and poor at best.

question: Does your trunk have a light that turns on when the lid is opened?

 

[Captain Kilowatt]

the lock mechanism latch has a sliding contact, just like door hinges. the contact is erratic and poor at best.

question: Does your trunk have a light that turns on when the lid is opened?

You had to be there to fully understand the meter readings and such. The latch was actually making a decent contact however the hinges were the issue. It's all irrelevant now because like I said, I HAD. My Tundra Crew Max I now have doesn't have that problem.

 

[w9cll]

Hey guys I got a Wilson 4 ft on the top of my flatbed headache rack all my connections are right and tight good ground bed is grounded to the chassis but that damn SWR changes I notice cause my receive is different all the time some days I have to turn gain up farther to hear anything some days I have to turn it down cause it's blaring and I noticed my swr is different when that happens I always check it on 1 and 40 it never goes over 1.5 but some days it's like 1.2 on both other days it's 1.5 on 40 and 1.2 on 1 and vice verse

What's going on?
It's not the radio cause it does it on all 4 of them I been working on all Cobras

Anything 2 or under is acceptable

 

[WMS]

Some good advice was given in this Thread...
Here's another point... Most people connect the SWR Meter closest to the Radio to Test... NOT the best option... Most knowledgeable people Test the SWR at the Antenna... Yeah, no one does, because that would take 2 People to do, as one's Arms are only so long... Of course, the way the Antenna is constructed too may prevent Testing at the Antenna... But the ARRL and most Antenna Guru's suggest the SWR should be Measured at the Antenna for the most Accurate Readings, as the Radio's Circuitry can act-upon the SWR Meter used nearest the Radio... The Length of Coax can also have an effect on the Actual SWR, which is another reason to Test at the Antenna...
Just something else to think about...

 

[fourstringburn]

Some good advice was given in this Thread...
Here's another point... Most people connect the SWR Meter closest to the Radio to Test... NOT the best option... Most knowledgeable people Test the SWR at the Antenna... Yeah, no one does, because that would take 2 People to do, as one's Arms are only so long... Of course, the way the Antenna is constructed too may prevent Testing at the Antenna... But the ARRL and most Antenna Guru's suggest the SWR should be Measured at the Antenna for the most Accurate Readings, as the Radio's Circuitry can act-upon the SWR Meter used nearest the Radio...
Just something else to think about...

Correct! But not always practical due to limitations as you stated.

Best and easiest way is to use an antenna analyzer with a short jumper at the antenna feed point to tune the antenna first, Then external SWR meters are fine to have at a convenient location for monitoring.There shouldn't be much difference in readings if coax is good with good connectors and installed properly.

If there are any good CB shops left worth their salts, they should have an antenna analyzer to do antenna checks.

 

[The DB]

Some good advice was given in this Thread...
Here's another point... Most people connect the SWR Meter closest to the Radio to Test... NOT the best option... Most knowledgeable people Test the SWR at the Antenna... Yeah, no one does, because that would take 2 People to do, as one's Arms are only so long... Of course, the way the Antenna is constructed too may prevent Testing at the Antenna... But the ARRL and most Antenna Guru's suggest the SWR should be Measured at the Antenna for the most Accurate Readings,

So far so good, but not always feasible. Honestly a HT unit with an antenna adapter output is useful for this...

as the Radio's Circuitry can act-upon the SWR Meter used nearest the Radio...

Here is where you went wrong. The radio will have no effect on SWR. SWR meters simply compare the voltage (actually most use current, same results so no biggie) going in one direction, and compare to the voltage (or current) going in the other direction. Changing the components in the radio can change the voltage or current output, but they will not affect the ratio of forward to reflected power. I've actually done an experiment that has confirmed this in the past (there is a thread on this forum somewhere about it).

The Length of Coax can also have an effect on the actual SWR, which is another reason to Test at the Antenna...
Just something else to think about...

And back to the good info. Coax will make SWR appear to be better than it is. 100' of RG-58 can make a 4.5:1 SWR appear to be lower than 1.5:1 SWR, numbers come from a direct measurement in the past (another old thread somewhere on this forum, even older than the last one I mentioned...). Higher quality coax takes more length for a similar effect. If adding a few feet of coax makes your SWR go up, or significantly change in any direction then you have a problem somewhere that need to be dealt with.


The DB

 

[WMS]

If you're using Cheap Coax with little Shielding such as most that is used in Mobile Installations, the Signal leaving the Coax through the Shield I imagine will act upon the Meter... Throw an Amplifier in the Mix... What happens then ? Ever hear of Stray RF ?
Glad to hear you've done a Test... Your Test, Your Result(s), others' Results may Vary... Where were the Test results revealed ? In QST Magazine or other ? The ARRL Handbook ? Or just this, Forum ?
I don't intend to argue... I trust the ARRL and Bill Orr's work more, no offense... Unless you can refer me to a Book you have Authored on the Subject that has been Critiqued by your Peers... ???
If a Particular Coax length made any Difference, the Cable Company would be using it... I am not buying Coax length has anything to do with anything... One Manufacturer's RG-8 is not the same as any others RG-8...
There are TOO MANY Variables to consider in regards to ANY Test... Was your Test done in a Laboratory Environment ? Using Laboratory Grade Test Equipment ? Please provide Photos...
Everyone will do as He / She pleases when it comes to Radio, regardless...

I always have a good Laugh when I read, " I did a Test "... Your Test... Your Result(s)... NOT Everyone's Results would be the same...

Back to the Good Info... Whatever works for you is Good...

 

[The DB]

Glad to hear you've done a Test... Your Test, Your Result(s), others' Results may Vary... Where were the Test results revealed ? In QST Magazine or other ? The ARRL Handbook ? Or just this, Forum ?

This and a few other forums, although they were years ago. Feel free to dig them up. A lot of good information in them, and if you go back far enough you can see the growth that resulted from of my study of "Generally Accepted Antenna Theory" (as opposed to that guys antenna theory) over time.

I don't intend to argue... I trust the ARRL and Bill Orr's work more, no offense... Unless you can refer me to a Book you have Authored on the Subject that has been Critiqued by your Peers... ???

None of my test results have ever disagreed with the ARRL Antenna Book series, and I have (and read cover to cover) all but three books in said series. If anything they confirmed said book series accuracy. I have not read Bill Orr's works so I have no comment on said books, although I have heard good things about them.

There are TOO MANY Variables to consider in regards to ANY Test... Was your Test done in a Laboratory Environment ? Using Laboratory Grade Test Equipment ? Please provide Photos...

I did provide photos of the VNA test results with both tests, along with several that documented the processes I used. The VNA is an AIM 4170c, the best piece of test equipment I could afford at the time, and according to direct comparisons done by engineers, comparable to HP lab equipment of the day.

Everyone will do as He / She pleases when it comes to Radio, regardless...

No argument here, some people want to believe certain things irregardless of reality.

I always have a good Laugh when I read, " I did a Test "... Your Test... Your Result(s)... NOT Everyone's Results would be the same...

For me, it depends on who did the test, what steps they took, what concerns they and others had about the process the equipment used and the results, namely the results are in line with what I can confirm through said books. When it comes to "experience" I have yet to produce a result that said books haven't been able to explain. If what I tested didn't match with what I expected, I want to know why. The why is everything to me, for it leads to understanding.

Just a note, my collection of antenna books includes engineering level textbooks. If you dig around enough on these forums you will find some quotes from them. I'm sure more will be posted, although, in general, the ARRL series of antenna books is written in a way that is a lot easier for most people to understand when explaining something or defending a position...


The DB

 

[WMS]

You started it with saying, I was wrong... You chose to discredit me for no reason...You CANNOT prove anything I said, was wrong... No one can... There is no Right or Wrong as everyone's Equipment varies... You can believe anything you want...
The only difference between Right and Wrong is a matter of one's Opinion...
Throw an Antenna Tuner inline and one can fool any meter to read anything...
If saying I was wrong makes you feel better, great...

Why people chase Rainbows, I'll never know... ALL My Radios work and I am the one who works on them and that is Good enough for me...
No, I am not a Licensed HAM as I do not like the HAM Superiority Complex...

I don't need / want a License, it's ONLY Radio...

 

[Captain Kilowatt]

If you're using Cheap Coax with little Shielding such as most that is used in Mobile Installations, the Signal leaving the Coax through the Shield I imagine will act upon the Meter... Throw an Amplifier in the Mix... What happens then ? Ever hear of Stray RF ?
Glad to hear you've done a Test... Your Test, Your Result(s), others' Results may Vary... Where were the Test results revealed ? In QST Magazine or other ? The ARRL Handbook ? Or just this, Forum ?
I don't intend to argue... I trust the ARRL and Bill Orr's work more, no offense... Unless you can refer me to a Book you have Authored on the Subject that has been Critiqued by your Peers... ???
If a Particular Coax length made any Difference, the Cable Company would be using it... I am not buying Coax length has anything to do with anything... One Manufacturer's RG-8 is not the same as any others RG-8...
There are TOO MANY Variables to consider in regards to ANY Test... Was your Test done in a Laboratory Environment ? Using Laboratory Grade Test Equipment ? Please provide Photos...
Everyone will do as He / She pleases when it comes to Radio, regardless...

I always have a good Laugh when I read, " I did a Test "... Your Test... Your Result(s)... NOT Everyone's Results would be the same...

Back to the Good Info... Whatever works for you is Good...

Stray RF will not affect an SWR meter. You even say "I imagine" so you yourself are not even sure yet you purport it to be the truth.

 

[Captain Kilowatt]

You started it with saying, I was wrong... You chose to discredit me for no reason...You CANNOT prove anything I said, was wrong... No one can... There is no Right or Wrong as everyone's Equipment varies... You can believe anything you want...
The only difference between Right and Wrong is a matter of one's Opinion...
Throw an Antenna Tuner inline and one can fool any meter to read anything...
If saying I was wrong makes you feel better, great...

Why people chase Rainbows, I'll never know... ALL My Radios work and I am the one who works on them and that is Good enough for me...
No, I am not a Licensed HAM as I do not like the HAM Superiority Complex...

I don't need / want a License, it's ONLY Radio...

Another one that thinks like that. It is apparent however that you DO have a superiority complex even if it is not the perceived HAM type.