Sounds logical. Agree or disagree?

[Road Squawker]

...Look at a 5/8 wave antenna. It's not resonant so some kind of matching device has to be used. That matching device is making the antenna work but not really fooling anything....

Gee, I dunno what you mean by "work"


All that the matching device is doing is allowing the exciter to deliver its power to the load.

it doesn't matter (within reason) what the SWR is, ALL the transmitters power will be radiated.

 

[543_Dallas]

Gee, I dunno what you mean by "work"


All that the matching device is doing is allowing the exciter to deliver its power to the load.

it doesn't matter (within reason) what the SWR is, ALL the transmitters power will be radiated.

What I mean is the system as a whole works more efficiently due to the matching device. Are you really that dense or just a prick?

 

[bob85]

Tallman,
my comments are not aimed at anybody on the forum, I was responding to the thread,

The writer of the article seems to not know his impedance transformation from vswr or what causes coax to radiate and he's fooled by tuners,

you don't need to read anything more technical than the instruction manual for mfj analyzers to find the truth,


The saying is something I read in another discussion, I guess its worded to provoke but it's true,
"vswr meters make you stupid" is another

If it makes somebody question or challenge the saying = good

If it gets somebody mad because its not what they believed or been posting and telling their locals for years they may go look for the truth = good,

If it makes somebody think hmmm I don't know what they are talking about but I'm going to look it up = good

If it makes people who have read a book smile = good

 

[Tallman]

Tallman,
my comments are not aimed at anybody on the forum, I was responding to the thread,

The writer of the article seems to not know his impedance transformation from vswr or what causes coax to radiate and he's fooled by tuners,

Okey Dokey. I just took it personal. No harm no foul?

 

[bob85]

No problem here Tallman, you see how it works, it made you go look for and post info,
you probably won't forget it,

lets look at mfj MFJ say about swr and coax length,

4. Feedline and SWR:
If all is well, feedline length won't have much impact on SWR readings.
You should be able to add or remove cable or measure SWR at any point along the way with little change.
It's normal to see a small SWR drop when adding cable or an increase when removing it because of resistive loss.
But, if you see big SWR changes when altering feedline length, repositioning the cable, or grounding the shield at any point, suspect a problem.

5. Radiating Feedlines:
Common-Mode RF Current flowing along the outer surface of the coax shield is always be a prime suspect when you see erratic SWR changes.
It happens when the feedline becomes part of the antenna element and radiates RF (hence the sensitivity to cable length, positioning, and grounding).
With a radiating feed, it's virtually impossible to measure the antenna's actual resonant frequency or SWR because the load presented by the feedline alters these parameters unpredictably.

 

[N0NB]

While MFJ gets a lot of flak, some of it deserved, in this case they got it right. For the frequency range that most are likely to use an analyzer the part about adding or subtracting feedline is largely true. As we get into the upper UHF range where losses become considerable due to line attenuation, the line loss needs to be taken into account in order to accurately determine the VSWR at the antenna feedpoint. I've dealt with this in 900 MHz RFID readers that run low power where even a seemingly modest amount of reflected power in the hut is a sign of a serious problem with the line or antenna and the reader fails.

 

[bob85]

What we need is a saying that will help MFJ remember how many nuts & bolts go into each piece of kit & nuts bolts screws washers and pieces of swarf thrown in as ballast don't count,

like walt says,
to know the vswr at the feedpoint you only need know the loss per unit length of your coax at your frequency, distance from meter to load, vswr @ the meter.

 

[Captain Kilowatt]

While MFJ gets a lot of flak, some of it deserved, in this case they got it right. For the frequency range that most are likely to use an analyzer the part about adding or subtracting feedline is largely true. As we get into the upper UHF range where losses become considerable due to line attenuation, the line loss needs to be taken into account in order to accurately determine the VSWR at the antenna feedpoint. I've dealt with this in 900 MHz RFID readers that run low power where even a seemingly modest amount of reflected power in the hut is a sign of a serious problem with the line or antenna and the reader fails.

That reminds me of the time I connected a 960 MHz transmitter to a roll of RG-58 which was open circuit on the other end just to prove a point to someone. The power meter said all was fine with 20 watts forward and negligible reflected but the TX range was only to the other side of the building. LOL

 

[Road Squawker]

What I mean is the system as a whole .... Are you really that dense or just a prick?

Ah yes,............. the "system as a whole...." concept,.........
thats right up there with the "fools the transmitter" concept too

 

[543_Dallas]

Ah yes,............. the "system as a whole...." concept,.........
thats right up there with the "fools the transmitter" concept too

How so? The transmitter can deliver full output because it is working into a 50 ohm load. VSWR on the coax is low because the matching device is at the antenna end, this means coax loss is kept to a minimum. Wouldn't you say the whole system is working well? It doesn't matter what I say or how I say it to you because you will find some way to manipulate it.

If you aren't just trying to be an ass please enlighten the fools with your knowledge. That would be much more useful than your usual condescending bullshit and arguing semantics with people you feel are below you. Maybe you're compensating for something. I'm sure I used some improper terms in this post, and I expect you to make the necessary corrections and have it on my desk by noon.