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what is your vswr at the antenna?
- Thread starter bob85
- Start date
Hey, I've been wanting to do the double-male pl259 thing at the feed point of my mobile antenna, which has a through-the-roof mount. I went into a trusted CB shop, and he said to never do that, that I should have at least a foot of coax between the meter and the antenna. He wouldn't elaborate. What's the deal?
I suppose. I tell you what, I'm very close to taking the Ronco approach to radio. Set it and forget it, although I've never been that type of person. Lol
Only thing I can think of is the strain you would apply to the meter jack if you bumped it at all. No other reason I can possibly think of.
I don't think road squarker fixed anything. I think the lesson in this is to not pay too close attention to your SWR because in most cases, it does not translate to much.
I reckon Bob85 is full of shit. There are not enough parameters to calculate anything. This could be a low and insulting blow against CBers. I could be wrong about this, he may very well believe in his own bullshit. Be aware of people spreading crap, and don't fold to people just because they claim to know more than yourself.
Road Squawker, what I said is correct. Why do you pretend to be some kind of aficionado, the feed line impedance has nothing to do with the fundamentals of standing wave ratio that I was pointing out. Please refrain from crossing out my posts in the future.
I'm going to go out on a limb here, The VSWR at the antenna is irrelevant.
The VSWR at the back of the transmitter is the only thing that counts.
Low VSWR does not mean the antenna is resonant. The VSWR is only important for the protection of the transmitter finals.
If you want to test for resonance use a field strength meter at 100', Make an adjustment and check to see if the RF level has increased or decreased.(Poor method)
If you have an antenna analyzer you can better tell what is going on.(Best method)
The VSWR at the back of the transmitter is the only thing that counts.
Low VSWR does not mean the antenna is resonant. The VSWR is only important for the protection of the transmitter finals.
If you want to test for resonance use a field strength meter at 100', Make an adjustment and check to see if the RF level has increased or decreased.(Poor method)
If you have an antenna analyzer you can better tell what is going on.(Best method)
So you reckon Bob85 is "full of shit"? Why, because he gave a scenario and asked a question about it? Where is the crap in asking a question? Or were you referring to another post that you didn't quote?
A word of advice, Bob85 is one of the most knowledgeable people on this forum. He doesn't post often, and typically when he does it is in response to the higher level tech conversations. If you are going to claim what he is saying is BS, you need more than just words.
If you truly believe he is wrong about something demonstrate it. Explain why he is wrong, otherwise you have nothing but claims with no backing.
The DB
A lot of people just assume resonance means the best performance, and I see where it appears to make sense (at first glance). I have seen with my own eyes, using a remote spectrum analyzer receiver (so I am not close enough to change the reading) and comparing that to VNA measurements taken at the antenna's feed point, that it is just not the case.
The DB
Resonance used to mean a 50 ohm impedance, in 99 % of the cases it is not. The 1/4 wave CB antenna is between 25 to 35 ohms and is still reactive. Could be capacitive or inductive depending on the surrounding ground plane.
You solve it, either yourself or Bob. Give the answer with the method and calculations.