lou franklin told you the truth,but its the fibreglass that changes the velocity factor,not the different types of metal,theres very little difference in propagation speed between copper,steel or aluminium.
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102" stainless whip
- Thread starter rwlack
- Start date
lou franklin told you the truth,but its the fibreglass that changes the velocity factor,not the different types of metal,theres very little difference in propagation speed between copper,steel or aluminium.
not in the antenna we are discussing here, which is a full size quarter wave whip.
there are many fiberglass antennas that are helical wound, but not this one.
the bone of contention here is "why" a fiberglass whip is 6" shorter than its stainless steel counterpart.
i started all this with a misinterpretation of something i had read, and tried to egg mack into debating it with me, but he wouldnt bite. LOL
i dont know what W5LZ is talking about; i never concluded what he concluded that i had concluded.
maybe he got up too early.
upon re-reading the the section of lou franklin's book, it turns out he said the reason is because copper is a better conductor than stainless steel and thats why its shorter.
whether or not thats the truth the whole truth and nothing but the truth i dont know, but maybe someone else here does?!
LC
there are many fiberglass antennas that are helical wound, but not this one.
the bone of contention here is "why" a fiberglass whip is 6" shorter than its stainless steel counterpart.
i started all this with a misinterpretation of something i had read, and tried to egg mack into debating it with me, but he wouldnt bite. LOL
i dont know what W5LZ is talking about; i never concluded what he concluded that i had concluded.
maybe he got up too early.
upon re-reading the the section of lou franklin's book, it turns out he said the reason is because copper is a better conductor than stainless steel and thats why its shorter.
whether or not thats the truth the whole truth and nothing but the truth i dont know, but maybe someone else here does?!
LC
Is that self analysis?
Nonsense,if someone is smart enough to use coax to transform impedance then they are most likely smart enough to use a cable rated high enough to do the job.
depends what type of coax and what frequency its used on if 9 feet or 18 feet has significance,at 27 mhz using cable with a .66 velocity factor the 18 foot of that coax would roughly be 3/4 wave.9 foot would be 3/8 wave.
18 feet of coax is used on some cb antennas,k40 etc to transform impedance,try replacing that 18 foot with any other length and you'll never match it.It is nothing to do with practical use.
Finally you give some sound advice,hallelujah !!!
not in the antenna we are discussing here, which is a full size quarter wave whip.
there are many fiberglass antennas that are helical wound, but not this one.
the bone of contention here is "why" a fiberglass whip is 6" shorter than its stainless steel counterpart.
i started all this with a misinterpretation of something i had read, and tried to egg mack into debating it with me, but he wouldnt bite. LOL
i dont know what W5LZ is talking about; i never concluded what he concluded that i had concluded.
maybe he got up too early.
upon re-reading the the section of lou franklin's book, it turns out he said the reason is because copper is a better conductor than stainless steel and thats why its shorter.
whether or not thats the truth the whole truth and nothing but the truth i dont know, but maybe someone else here does?!
LC
i was referring to both a 1/4 wave stainless whip and a 1/4 wave fibreglass non helically wound whip.
the reason the fibreglass one is shorter is as i stated before the fibreglass reduces the speed of wave propagation.if you surrounded the steel whip in fibreglass it would have the exact same effect of shortening the whip.
No-one knows what Doc is talking about,least of all Doc himself.
:headbang:headbang
thanks jazzsinger, that makes sense.
it does mean that lou was wrong in "understanding and repairing CB radios" though, as he stated it was because copper was a better conductor than stainless steel.
LC
it does mean that lou was wrong in "understanding and repairing CB radios" though, as he stated it was because copper was a better conductor than stainless steel.
LC
"Is that self analysis?"
Not particularly, although I do make mistakes.
"Nonsense,if someone is smart enough to use coax to transform impedance then they are most likely smart enough to use a cable rated high enough to do the job."
I'm afraid that's one of those things that just don't follow through. Most people use coax for impedance transformation because they don't know any better. Because they "hear" that's the length to use and have no idea why it's used at all.
"depends what type of coax and what frequency its used on if 9 feet or 18 feet has significance,at 27 mhz using cable with a .66 velocity factor the 18 foot of that coax would roughly be 3/4 wave.9 foot would be 3/8 wave."
And pray tell, what significance is that 3/4 w, or 3/8 w, at 27 Mhz? They would be a 1/2 or 1/4 electrical wave at 17 - 18 Mhz though, but that's not much good at 27 Mhz. Oh, I can see where that electrical 3/4 wave might come in handy if you only needed an electrical 1/4 wave which might be too short to reach, and since an electrical 1/2 wave is sort of 'neutral'/'invisible', just an extender type of thingy at 27 Mhz.
"18 feet of coax is used on some cb antennas,k40 etc to transform impedance,try replacing that 18 foot with any other length and you'll never match it.It is nothing to do with practical use."
You might re-think that, cuz you're wrong there.
"That includes what I write too!
- 'Doc
Finally you give some sound advice,hallelujah !!!"
I'm glad you agree with me on being fallible. To bad you don't include yourself in that category.
"No-one knows what Doc is talking about,least of all Doc himself."
I agree with you on the first part of that statement, you don't know what I'm talking about. I would suggest you find out. I will partially agree with the second part of that statement, I don't know everything, and sometimes I do make mistakes, or incorrect assumptions, as I did about that 96" whip being helically wound. That doesn't change the fact that the rest of what I said was correct, just that it was mis-applied under the circumstances. That "L", "C", and resonance still holds true. Get used to it and learn how to use it, makes things a lot simpler. But then, that might not make any sense to you either...
- 'Doc
Not particularly, although I do make mistakes.
"Nonsense,if someone is smart enough to use coax to transform impedance then they are most likely smart enough to use a cable rated high enough to do the job."
I'm afraid that's one of those things that just don't follow through. Most people use coax for impedance transformation because they don't know any better. Because they "hear" that's the length to use and have no idea why it's used at all.
"depends what type of coax and what frequency its used on if 9 feet or 18 feet has significance,at 27 mhz using cable with a .66 velocity factor the 18 foot of that coax would roughly be 3/4 wave.9 foot would be 3/8 wave."
And pray tell, what significance is that 3/4 w, or 3/8 w, at 27 Mhz? They would be a 1/2 or 1/4 electrical wave at 17 - 18 Mhz though, but that's not much good at 27 Mhz. Oh, I can see where that electrical 3/4 wave might come in handy if you only needed an electrical 1/4 wave which might be too short to reach, and since an electrical 1/2 wave is sort of 'neutral'/'invisible', just an extender type of thingy at 27 Mhz.
"18 feet of coax is used on some cb antennas,k40 etc to transform impedance,try replacing that 18 foot with any other length and you'll never match it.It is nothing to do with practical use."
You might re-think that, cuz you're wrong there.
"That includes what I write too!
- 'Doc
Finally you give some sound advice,hallelujah !!!"
I'm glad you agree with me on being fallible. To bad you don't include yourself in that category.
"No-one knows what Doc is talking about,least of all Doc himself."
I agree with you on the first part of that statement, you don't know what I'm talking about. I would suggest you find out. I will partially agree with the second part of that statement, I don't know everything, and sometimes I do make mistakes, or incorrect assumptions, as I did about that 96" whip being helically wound. That doesn't change the fact that the rest of what I said was correct, just that it was mis-applied under the circumstances. That "L", "C", and resonance still holds true. Get used to it and learn how to use it, makes things a lot simpler. But then, that might not make any sense to you either...
- 'Doc
I didn't think that anyone sold the 96" fiberglass antenna anymore. I know RS still sells a very good 102" SS whip for $20.
Why is all this crap even being posted in the ¨Amateur¨ antenna section. Put it in the CB section with the rest of the ¨well I read me on the in-teer-net¨ comments. Leave this section for those who actually know about or want to learn about electronic principles, and don´t just talk out of their rear.
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I would imagine very few people use coax for impedance transformation,A) because they don't understand how or why it works and B) most just use an atu because its simpler,although not necessarily better.Those that do use it are generally smart enough to figure out the limitations of the transmission line they use.
an electrical 1/2 wave isn't neutral or invisible,its an impedance repeater,3/4 wave or 3/8 wave would both transform impedance to varying degrees.
You sure about that?
Oh i'm very fallible.
Gobbledygook.
You'll notice i didn't mention your reference to a coil/helical winding's purpose being to tune out reactance,and not making up the missing length,because i agreed with you.UNBELIEVABLY.
i'm well aware of how to use L, C, reactance and resonance,despite what you may or may not think,not all cb'ers are dumb in much the same way not all amateurs are smart.
Incidentally have you got your head round how a vswr meter works yet? It doesn't measure impedance.
Yeah amateurs all know about electronic princples and none talk from their rear,quality
I take it you've never read eham,where there is more bullshit typed than on any cb forum on the net?
jazzsinger.
"Incidentally have you got your head round how a vswr meter works yet? It doesn't measure impedance."
Contrary to what you might think, I do know that it isn't impedance that is being compared, but voltage or current depending on the design of that meter. The thing is, that voltage or current does follow the changes in impedance, otherwise, why bother measuring that voltage or current? So, in effect, you are 'measuring'/'comparing' impedances.
Have YOU gotten your mind around that yet? And it can be either a 'VSWR' or 'ISWR' meter. That 'ISWR' meter isn't seen very often though.
And since I think I've finally figured out why you are making these comments, I'm finished playing your game, you aren't worth the trouble.
- 'Doc
"Incidentally have you got your head round how a vswr meter works yet? It doesn't measure impedance."
Contrary to what you might think, I do know that it isn't impedance that is being compared, but voltage or current depending on the design of that meter. The thing is, that voltage or current does follow the changes in impedance, otherwise, why bother measuring that voltage or current? So, in effect, you are 'measuring'/'comparing' impedances.
Have YOU gotten your mind around that yet? And it can be either a 'VSWR' or 'ISWR' meter. That 'ISWR' meter isn't seen very often though.
And since I think I've finally figured out why you are making these comments, I'm finished playing your game, you aren't worth the trouble.
- 'Doc
nursecosmo,
i dont even know where to start with your post. LMAO
first of all, your post offers ABSOLUTELY NOTHING of substance to this discussion. This alone makes you a hypocrite.
what else would you call someone who posts about "crap being spewed" while offering nothing more than thinly veiled insults?
secondly, exactly how is a discussion about 1/4 wave mobile antennas made of different materials not relevant to amateur radio?
or did you simply form your opinion based upon the title of the thread?
third, it is obvious that you didnt bother reading the previous posts in this thread before posting your opinion.
well, either that or you just skimmed through them because you didnt understand what was being discussed.
to answer your question about why this thread is in the amateur antenna section, (which i wouldnt have to do if you had read the first few posts)
the OP was new to the forum and was not familiar with the correct place to post certain topics, and the moderators of this forum do not draw a "perceived intelligence" line between the CB and amateur sections of this forum as you seem to.
your reference to CB'ers hearing something on the internet and posting it also holds no merit, as the misinformation that started this discussion on antenna materials came from a book that is otherwise full of valuable radio knowledge.
the saddest thing is that you have been brainwashed into thinking that insulting CB operators somehow makes you sound more intelligent. LOL
i am very aware of where this brainwashing comes from.
it comes from talking to too many insecure ham ops.
after all, you cant be an elitist if you have no one to talk down to/ about.
ok, i feel that you have been satisfactorily trounced. please respond if you would like another.
LC
i dont even know where to start with your post. LMAO
first of all, your post offers ABSOLUTELY NOTHING of substance to this discussion. This alone makes you a hypocrite.
what else would you call someone who posts about "crap being spewed" while offering nothing more than thinly veiled insults?
secondly, exactly how is a discussion about 1/4 wave mobile antennas made of different materials not relevant to amateur radio?
or did you simply form your opinion based upon the title of the thread?
third, it is obvious that you didnt bother reading the previous posts in this thread before posting your opinion.
well, either that or you just skimmed through them because you didnt understand what was being discussed.
to answer your question about why this thread is in the amateur antenna section, (which i wouldnt have to do if you had read the first few posts)
the OP was new to the forum and was not familiar with the correct place to post certain topics, and the moderators of this forum do not draw a "perceived intelligence" line between the CB and amateur sections of this forum as you seem to.
your reference to CB'ers hearing something on the internet and posting it also holds no merit, as the misinformation that started this discussion on antenna materials came from a book that is otherwise full of valuable radio knowledge.
the saddest thing is that you have been brainwashed into thinking that insulting CB operators somehow makes you sound more intelligent. LOL
i am very aware of where this brainwashing comes from.
it comes from talking to too many insecure ham ops.
after all, you cant be an elitist if you have no one to talk down to/ about.
ok, i feel that you have been satisfactorily trounced. please respond if you would like another.
LC
OK Guys, Lets all get off the Insult train, and back on the Antenna subject at hand....Please.
These Questions can Apply to several HF Frequency's as well as 27 Mhz, 102/109" SS whips have been used for years for 10, 11, 12, meters...and so on. Cut it down for higher frequency's , add length for lower frequency's.
73
Jeff
These Questions can Apply to several HF Frequency's as well as 27 Mhz, 102/109" SS whips have been used for years for 10, 11, 12, meters...and so on. Cut it down for higher frequency's , add length for lower frequency's.
73
Jeff
loosecannon: You are right to fault me for making any derogatory remarks about CBers in general and I apologize for that ( I was in a particularly bad mood, which is no excuse.). There seems to be just as much BS coming from licensed hams in this thread as anyone.
On the matter of coax length to adjust VSWR; yes it can adjust VSWR at the transmitter on a mismatched antenna. Should the antenna impedance be matched to the transmitter this way? No.
On the matter of antenna length of a fiberglass vs SS whip; I am not familiar with that particular antenna, but none of the fiberglass antennas I have ever seen have a copper ¨wire¨ running up through the glass. Rather, they have a copper ¨strip¨ partially wrapped around a fiberglass center rod, then covered with shrink wrap. If both antennas have the same electrical length, the difference in physical length occurs mostly because of the difference in radiator length/width ratio between the wide strip and narrow whip.
There is a very small VF factor difference between the SS and copper radiators, but not enough to account for a 6% difference. While there is a significant difference between these metals when used as feed-lines, when compared as radiators, there is not much difference. The fiberglass used used in the above mentioned antenna is not in a very intimate contact with the radiator and so does not have an appreciable effect on the VF.
On the matter of coax length to adjust VSWR; yes it can adjust VSWR at the transmitter on a mismatched antenna. Should the antenna impedance be matched to the transmitter this way? No.
On the matter of antenna length of a fiberglass vs SS whip; I am not familiar with that particular antenna, but none of the fiberglass antennas I have ever seen have a copper ¨wire¨ running up through the glass. Rather, they have a copper ¨strip¨ partially wrapped around a fiberglass center rod, then covered with shrink wrap. If both antennas have the same electrical length, the difference in physical length occurs mostly because of the difference in radiator length/width ratio between the wide strip and narrow whip.
There is a very small VF factor difference between the SS and copper radiators, but not enough to account for a 6% difference. While there is a significant difference between these metals when used as feed-lines, when compared as radiators, there is not much difference. The fiberglass used used in the above mentioned antenna is not in a very intimate contact with the radiator and so does not have an appreciable effect on the VF.
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