| Author |
Message |
    
Beeker7104
Junior Member
Username: Beeker7104
Post Number: 35
Registered: 12-2004
| | Posted on Friday, October 14, 2005 - 9:40 pm: | 
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From reading about the way coax is supposed to behave on a radio installment Why is it that the manufacturers of the proverbial coax don't change its characteristics so that it will perform as it is supposed to? From my understanding it should not matter the length of the coax because the SWR ratio shouldn't change. By Shortening the Antenna it should change....SO, Why are radios/antennas built so mis-leadingly? This understanding of coax length nad how it acts is somewhat confusing, But after reading the lengthy post I found on another site,I have a better understanding of it a little(i think). |
Hollowpoint445
Advanced Member
Username: Hollowpoint445
Post Number: 824
Registered: 6-2004
| | Posted on Saturday, October 15, 2005 - 4:23 pm: |
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Because radio waves propogate through coax just the same as they do any other medium. It would be nice if the manufacturers could change the laws of physics to make it easy for us to hook up a CB antennas - but they cannot.
In most installations the length of coax really doesn't matter much at all. Only folks who are really particular about their stations bother to measure/trim coax to 1/2 wavelength multiples. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1686
Registered: 7-2004
| | Posted on Saturday, October 15, 2005 - 6:47 pm: |
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odd multiples
sorry |
Hollowpoint445
Advanced Member
Username: Hollowpoint445
Post Number: 826
Registered: 6-2004
| | Posted on Saturday, October 15, 2005 - 7:52 pm: |
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No, just 1/2 wavelength multiples. Think about it for a minute. If a 1/2 wavelength multiple indicates a true impedance reading, then why would a full wavelength multiple have an incorrect one? It's just two 1/2 wavelength multiples.
A 1/4 wavelength piece of coax is an impedance inverter, so you would need an odd 1/4 wavelength multiple to invert impedance, but all even 1/4 wavelength multiples would show correct impedance. Another way of saying that is 1/2 wavelength multiples.
I think at one point you said you have Lou Franklin's "Understanding and Repairing CB Radios" on your bookshelf. Turn to page 314 and look at figure 8-8 and read the associated text. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1692
Registered: 7-2004
| | Posted on Saturday, October 15, 2005 - 8:24 pm: |
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OK OK, you're making me run all over the place for my books here, hollow.
YES last paragraph before 'coax characteristics' DOES state '...use a 1/2 wavelength of coax or its multiple (2/2, 3/2, 4/2, 5/2, etc.) instead...'
NOW if you go to lou's OTHER classic, 'screwdriver expert', go to page 18, myth #2, 2nd paragraph, '...anything other then an ODD multiple of a half-wavelength (1/2, 3/2, 5/2 etc.), you would observe 2 different SWR readings...'
SO, while your statement IS CORRECT, the better choice to read SWR's-AS PER LOU FRANKLIN-would be to go with ODD multiples of a 1/2 wave, so you don't see 'fictitious' readings. actually the 1st time i saw that-to use odd multiples of 1/2 wavelength coax MULTIPLIED by velocity factor-was in high school communications electronics class, in an ARRL publication, quite possibly a mid-70's amateur radio handbook, or antenna compendium...something ARRL, because that was all they used.
so yes, YOU ARE CORRECT, but for CBers, who take what they hear as law, the 'odd multiple' is probably better, or there will be tons of 'i saw 1.3 with meter here & 2 here-which is it? AHHHH!'
i've used the odd multiple since 76 or 77 without any trouble, it's as true & correct as using ANY 1/2 wavelength, it works & it's what i know, so, i shall continue to go that route |
Hollowpoint445
Advanced Member
Username: Hollowpoint445
Post Number: 831
Registered: 6-2004
| | Posted on Saturday, October 15, 2005 - 9:25 pm: |
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There is no difference between the odd multiple and the even multiple of 1/2 wavelength. 1/2 wavelength is an impedance repeater, so any 1/2 wavelength multiple would give you an accurate VSWR reading.
Lou and/or his editor apparently got it wrong in the Screwdriver Expert's Guide. |
Outkast
Junior Member
Username: Outkast
Post Number: 31
Registered: 9-2005
| | Posted on Sunday, October 16, 2005 - 2:37 am: |
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I just think this is a debate that will go on for all time kinda like Chevy VS. Ford, no one can find trully definate answer either way, but how many people you know that measured to the exact anyways? |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1703
Registered: 7-2004
| | Posted on Sunday, October 16, 2005 - 7:19 pm: |
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lou stands by '...anything other then an ODD multiple of a half-wavelength (1/2, 3/2, 5/2 etc.), you would observe 2 different SWR readings...'-DEPENDING ON WHERE YOU PLACE THE SWR METER, at the transceiver, at the antenna or at a 1/4 wave or 1/2 wave point away from either...
but, hey, my SWRs are 1.0:1 on nearly 15 channels using 1/2 wave(27.2 mHz) x 84% velocity factor of 9913 coax. did coax length matter? who knows, that was the only length i tried
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Hollowpoint445
Advanced Member
Username: Hollowpoint445
Post Number: 833
Registered: 6-2004
| | Posted on Monday, October 17, 2005 - 9:00 am: |
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It's interesting that he offers no reason for odd multiples of 1/2 wavelength in the Screwdriver Expert's Guide, and in Understanding and Repairing CBs (a MUCH more thorough and technical book) he doesn't even mention odd multiples.
He does write that "Since this pattern repeats itself regularly every 1/2 wavelength, this coax length is and impedance repeater."
Why use another 11' or more of coax if you don't need it?
Outkast - It's not an opinion or preference like Chevy vs. Ford. There is an actual scientific answer - 1/2 wavelength multiples repeat the impedance of the antenna to the radio end of the coax.
People argue about coax length because often they're promoting one point of view or another, and both have their merits. The truth is that coax length DOES effect the VSWR the radio sees. The worse the antenna match the more difference it makes. If you want the radio to see the antenna impedance you should use 1/2 wavelength multiples of coax. |
Airplane1
Advanced Member
Username: Airplane1
Post Number: 592
Registered: 5-2004
| | Posted on Monday, October 17, 2005 - 9:11 am: |
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What if you use a few inch piece of coax and hook an anilizer to your antenna. will that give you a accurate reading?
then just hook up what ever length of coax to connect your radio to antenna. |
Hollowpoint445
Advanced Member
Username: Hollowpoint445
Post Number: 835
Registered: 6-2004
| | Posted on Monday, October 17, 2005 - 9:19 am: |
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Airplane1 - If the antenna is perfectly matched the length of coax doesn't matter. Using a short piece of coax to match the antenna is fine. |
Chad
Advanced Member
Username: Chad
Post Number: 509
Registered: 11-2004
| | Posted on Monday, October 17, 2005 - 12:15 pm: |
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I'm happy when the coax makes it to the antenna.... Lon was not happy (I presume) when the coax made it to the antenna but not the rig  |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1722
Registered: 7-2004
| | Posted on Monday, October 17, 2005 - 4:50 pm: |
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actually, hollowpoint, HE DOES give explanation in the screwdriver experts guide, the last paragraph on page 18 states,
'back to that coax length:all you really need to know is that an odd multiple of a 1/2 wave length will indicate approximately the same SWr at both ends of your system; i.e., whatever 'impedance' exists at the antenna will show up at the CB, where it is transformed electronically into a specific SWR number....problem:if you end up with an odd multiple of a 1/4 wavelength(true physical length, velocity factor included) you may NOT get an accurate reading at the CB end. such a coax length inverts the antenna reading. for example, a 25 ohm antenna might indicate something much higher then the 50 ohm coax and CB, as shown on your SWR meter. and if the antenna were higher then 50 ohms, it would reflect a lower then 50 ohm reading at the CB end where you placed the swr meter. so that is why cutting the coax will NOT really change the actual SWR that exists AT THE ANTENNA.'
the key words are 'may' and 'can', not neccessarily DO and WILL. these phenomena can be witnessed when you show GOOD swr's, but HIGH reflect. how & why did that happen? sometimes from placement, sometimes actually 'reflect' from an object, even rf feeding back from an amp thru TOO SHORT OF A PIECE of coax between amp & radio. other times, the LENGTH OF THE COAX FROM OUTPUT TO ANTENNA is doing exactly what lou states above, & it can do it both ways-showing 'good' when really bad, & showing 'bad' when really good.
do these problems arise EVERY SINGLE time? NO. sometimes, rerouting coax, or moving the actual placement of a piece changes & corrects everyhting.
if you are placing a CB directly to a non tuneable antenna(102" whip), you are stuck with what you got, when you are ading amps, etc, it is best to make sure you have as little reflect as possible.
SO while 1/2 wavelength multiples is 100% correct, odd multiples thereof just helps to get TRUE swr readings...
NOW, if beeker HAD any hair, he'd be yanking it out RIGHT now.  |
Hollowpoint445
Advanced Member
Username: Hollowpoint445
Post Number: 837
Registered: 6-2004
| | Posted on Monday, October 17, 2005 - 9:45 pm: |
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Patzerozero - Your quote didn't explain why an ODD MULTIPLE of 1/2 wavelength was necessary instead of just a multiple of 1/2 wavelength.
Again I quote:
"Since this pattern repeats itself regularly every 1/2 wavelength, this coax length is an impedance repeater."
So if the impedance is repeated every 1/2 wavelength, then why use odd multiples? |
Outkast
Junior Member
Username: Outkast
Post Number: 39
Registered: 9-2005
| | Posted on Tuesday, October 18, 2005 - 3:29 am: |
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I was looking at a SWR/Antenna analyzer and found a little tid bit of information that I thought is kinda intresting. This is quoted directly from the Vectronics SWR-584B manual:
6) If SWR changes with coaxial line length, line placement or line grounding (Any distance from the antenna) changes, the feedline has one or more of the following:
a.) The feedline is carrying common mode current and radiating.
b.) The feedline is not 50 ohm line.
c.) The feedline has high loss.
Makes sense to me!!!
Outkast
CEF 650 |
Outkast
Junior Member
Username: Outkast
Post Number: 40
Registered: 9-2005
| | Posted on Tuesday, October 18, 2005 - 3:41 am: |
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By the way Pat a 102" can be tunned, its just a B**** and if you go to far its not like you can put some back on, you just clip it down tell you have the desired SWR and then crimp a new ball on top.
Outkast
CEF 650 |
Thehobo
Junior Member
Username: Thehobo
Post Number: 20
Registered: 2-2004
| | Posted on Tuesday, October 18, 2005 - 12:45 pm: |
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???s, if using a piece of coax that is rated at say, 1000 watts, (mini 8 ), is this at the rms or the peak wattage?? if at rms, then mini 8 v, which claims will take 2000, it wood hold a 1000 watt amp ok?? this is in a mobil with a short run of coax!! huummm.. lol..
thehobo
274150 am
monitor ch. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1727
Registered: 7-2004
| | Posted on Tuesday, October 18, 2005 - 4:11 pm: |
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yes, i know that outkast, but for 'ease of installation', tuneable by adjustable tip or stinger was what i was referring to...
i do not have time to look for where it can be found, but it has something to do with:'from an electrical standpoint, 1/2 wavelength and 2/2 and 4/2 and 6/2 etc wavelength are the same. 1/2, 3/2, 5/2 are not the same.' and while yes impedance is repeated every 1/2 wavelength, something happens on the full/even wavelengths, that does not on NON FULL WAVELENGTH ELECTRICAL LENGTHS...i know that is from lou franklin as well as amateur radio handbook. i only looked briefly, & really don't have time to look further right now.
from a 'basic' installation standpoint, the differences are probably not detectable, somebody who is looking to coax the last milliwatt from his radio, the least amount of line loss from super connectors on super hardline, or just happens to have an installation using multiple cables with multiple add ons showing fluky SWR readings, this would be a point to examine.
also correct outkast, regarding an antenna analyzer. and, it as well will show the TRUE R, Z, I of the coax no matter what the length, it is the SWR meter which will show false or incorrect readings, which is why a reflect meter is more useful in touchy situations (if an analyzer is not available). hence an SWR reading of 1.2:1 and reflect shown exceeding 50%. the reflect reading is correct, the SWR reading is NOT.
all said & done, use a brand/type of cable with THE BEST SHIELD POSSIBLE and LEAST AMOUNT OF LOSS POSSIBLE at the required length. 833 stated recently the pros of using 'double shielded' coax...KEEP YOUR SIGNAL IN THE COAX SO IT DOES NOT RADIATE TIL IT GETS TO THE ANTENNA, as well as keeping junk out... |
Hollowpoint445
Advanced Member
Username: Hollowpoint445
Post Number: 839
Registered: 6-2004
| | Posted on Tuesday, October 18, 2005 - 7:02 pm: |
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"The cure for suspicious SWR readings is to measure the antenna itself where practical. Base antennas use standard coax sockets but mobiles don't, so this isn't always possible. Use a 1/2-wavelength of coax or it's multiple (2/2, 3/2, 4/2, 5/2 etc.) instead. Such a length repeats whatever impedance actually exists at the antenna, while a 1/4-wavelength feedline inverts it."
Lou Franklin p314 Understanding and Repairing CB Radios |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1733
Registered: 7-2004
| | Posted on Wednesday, October 19, 2005 - 5:57 pm: |
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so maybe lou drinks |
Hollowpoint445
Advanced Member
Username: Hollowpoint445
Post Number: 842
Registered: 6-2004
| | Posted on Wednesday, October 19, 2005 - 8:43 pm: |
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As I said earlier, either he or his editor made a mistake with the Screwdriver Expert's Guide. While what was published was true, it wasn't 100% accurate. |
Tech8541
Moderator
Username: Tech8541
Post Number: 258
Registered: 12-2003
| | Posted on Tuesday, January 17, 2006 - 9:28 am: |
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both a 1/2 and a full wavelength repeats impedance. the difference is the odd multiples of a 1/2 wave cause voltages and currents to be 180* out of phase with the load (input to antenna). only a full wavelength and its multiples repeats everything. even then it is not exact due to changes introduced by the coax, but for all purposes it can be considered exact. |
Al_lafon
Intermediate Member
Username: Al_lafon
Post Number: 169
Registered: 3-2005
| | Posted on Wednesday, January 18, 2006 - 12:08 pm: |
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Man you guys make far to big a mess over SWR
i've never had this problems you have. If your
antenna is made right to start with it'll be
just find. Never buy off brand odd ball junk. |
Sinker
Intermediate Member
Username: Sinker
Post Number: 365
Registered: 8-2005
| | Posted on Wednesday, January 18, 2006 - 6:06 pm: |
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Well now my head hurts and I am really screwed up on this entire Coax deal. Was making some jumpers out of 213 and it seems like the cheapest stuff I have ever seen or touched. Anyway having a ton of problems getting everything right with my second radio. All is good till I add the jumpers and put the amp in line then everything goes south except for the SWR and Reflected Power which goes UP. |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1169
Registered: 7-2004
| | Posted on Wednesday, January 18, 2006 - 6:22 pm: |
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Sinker--The SWRs from antenna to radio are
fine? Correct? (Nothing in-line).
If so, your system is correct./ It shouldn't
matter what type of coax your using for
jumpers. You may have to play with jumper
length. I always just used 3 ft jumpers and
never had a problem.
How high is your SWRS with nothing in-line?
How high is SWRS with jumpers and other equipment in-line? |
Wildrat
Advanced Member
Username: Wildrat
Post Number: 683
Registered: 12-2003
| | Posted on Wednesday, January 18, 2006 - 6:47 pm: |
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Don't worry about all this coax stuff, make your jumpers to whatever length you need. Make sure you have a good hot soldering iron. Take a small file or sand paper and gently file or sand the area where you see the shield thru the holes. This will make the solder stick a little better. I also put flux on the area before I start to solder. Make sure you don't have any strands shorting you out before soldering. Those connectors when using 213 or any .5 dia. coax can be frustrating to get right, but the thing is if it's not pretty like you want it, take the conn. off cut off the messed up part and start again. After awhile you will get the hang of it. I don't know if any of this will help ya Sinker but just remember me and Starface are just a phone call away. You have my email add. and I ck my mail often during the day so if you have a question I may be able to help.
Mark |
Sinker
Intermediate Member
Username: Sinker
Post Number: 366
Registered: 8-2005
| | Posted on Wednesday, January 18, 2006 - 7:52 pm: |
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Road Warrior-
Channel 1 / 26.965 = 1.1:1
Channel 40 / 27.405 = 1.0:1
With amp in-line and on The reading at the radio still remains as that above but between the amp and antenna gets crazy at the following:
Channel 1 / 26.965 = 1.7:1
Channel 40 / 27.405 = 1.1:1
As you can see Channel 1 goes WAY up and scares me to use the amp any longer. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 2282
Registered: 7-2004
| | Posted on Wednesday, January 18, 2006 - 8:47 pm: |
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if radio output is variable, try turning it DOWN & see if & where swr goes back down to 1.1:1. if it's only say 50-100 watts off of a 400 watt dead key, it won't make much if any difference. PEP will not be affected by lowered carrier.
adding 50 watts to my dead key & they jump 1.1:1 to 2:1, like hitting a switch. back down & reflect disappears.
try LONGER jumper from radio to amp. 3' & my swr's are HIGH, 6' they are useable, 9' they don't move from amp off to on. reflect with 9' is 1-2%.
2x8 setup in my blazer with several jumpers, all needed to be 9' because of lengths needed to reach. never had any high reflect problems. |
Jameslarson
Intermediate Member
Username: Jameslarson
Post Number: 100
Registered: 4-2006
| | Posted on Wednesday, May 03, 2006 - 9:00 pm: |
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Pat, what do you mean when you say "the swr may be low, but the reflect is 50%". i thought they were one and the same. Please help, because When i check my SWR it is real low and good, but how do i check for reflection? I thought I was supposed to use the FWD switch to calibrate the FWD, and then switch over to REF to read my SWR's (Which are good). Help. |
Tech237
Moderator
Username: Tech237
Post Number: 323
Registered: 4-2004
| | Posted on Thursday, May 04, 2006 - 9:09 am: |
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SWR is a factor of pwer which in turn is a factor of votlage and resistance and/or current. Basic Ohms law.
If the power increases, your SWR reading will change. That is one reason any decnet radio and or antenna tuner manual will state something to the effect of after tuning at low power check and fine tune at full power levels.
Years ago I used to teach Marine radio, both boaters and a rescue group, and I used to teach them to tune the antenna initially on receive by tuning for the highest received noise/signal. This put the antenna/tuner combination in the ballpark and any powered tuning was then kept to a minimal. This was both nicer on the radio and to other users on the frequency. |
Tech833
Moderator
Username: Tech833
Post Number: 1341
Registered: 8-2002
| | Posted on Thursday, May 04, 2006 - 10:40 am: |
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I feel it is time to chime in.
Let me set the record straight. Coax length DOES affect the readings you see, but not the actual load. Let me explain.
Assuming your antenna has a perfect 50 ohm, j0 feedpoint load, then you will se that same load at the other end of any length of coax. To your radio, coax cable looks like a bunch of inductors in series with capacitors in parallel all the way through. Sorta like a low pass filter with the rolloff somewhere in the GHz. range. Since there are inductors in series, their resistance changes depending on the impedance at the ends. If the impedance was raised greatly on the ends, the coax 'looks' like the inductors get bigger (more turns and higher Q) and if the impedance drops on the ends, the inductors appear smaller (less turns, lower Q). This affects the rotation of the wave.
Assuming we have our perfect load at the opposite end, this is not an issue. Change the antenna feedpoint reactance by several ohms and the rotation becomes a critical factor which amplifies (exponentially) the reactance seen on the radio end. You might have 50 ohms, j+5 at the antenna, but after just 50 feet of coax, at 30 MHz., it will look something like 50 ohms, j+20. Now, change the coax length to 25 feet and it looks like 50 ohms, j-5. In the world of SWR, you just changed your SWR from 1.5:1 to less than 1.3:1 by changing the coax length. Also, you could make your transmitter happy by changing the load from capacitive to slightly inductive. Transmitters get real hot when feeding capacitive loads, but will tolerate a greatly inductive load more easily.
This really isn't a big issue if you only operate one frequency. However, if you operate over a range of frequencies, then it becomes more and more important. As AM stations begin to implement IBOC (HD broadcasting), rotation becomes a make-or-break factor in our antenna systems. Used to be, all we cared about was getting the impedance and reactance correct. Now, the rotation becomes an equally important factor. Why? Bandwidth and linearity over a wide frequency range! Especially in a directional array.
I should write a book, I've been told. I hate typing or I would. |
Bruce
Senior Member
Username: Bruce
Post Number: 3798
Registered: 9-2003
| | Posted on Thursday, May 04, 2006 - 9:53 am: |
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The lengh of coax will change the SWR reading on your meter HOWEVER not the real SWR .... |
Jameslarson
Intermediate Member
Username: Jameslarson
Post Number: 103
Registered: 4-2006
| | Posted on Thursday, May 04, 2006 - 4:27 pm: |
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OK, so let's say the SWR between my radio and amp is 3:1, but the SWR between the amp and antenna is 1:5. This is OK? Also, seeing that the SWR between the radio and amp is 3:1, am I now losing about 25% power from my radio to my amp (Instead of 4 watts let's say, am I only giving the amp 3 watts because the SWR between the radio and amp is 3:1 25%, even though the SWR from the amp to antenna is 1:5)? Thanks. |
Tech833
Moderator
Username: Tech833
Post Number: 1343
Registered: 8-2002
| | Posted on Thursday, May 04, 2006 - 8:52 pm: |
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If your SWR into the amp is high, it has nothing to do with your antenna. The amp's input tuning network needs to be adjusted. It is important to balance the input load on a class C amplifier so that the output tracks with the input in a linear fashion. In other words, what you feed is what comes out, only more of it. If not, you will get lot sof distortion in your signal, and maybe even produce spurs and TVI.
I have to assume you are doing this on ham frequencies, not CB since that is illegal on CB. So, since you are using a ham radio, if your radio has a built-in tuner (most ham HF radios do), it is a good idea to use that tuner to make your radio load match the amp input load until you can get around to fixing the amp's tuned input network. |
Jameslarson
Intermediate Member
Username: Jameslarson
Post Number: 105
Registered: 4-2006
| | Posted on Thursday, May 04, 2006 - 10:02 pm: |
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Well, for theoretical reasons, let's assume it is being used on 11 meter. The SWR's from the amp to the antenna is fine. The SWR from the radio to the amp is 3:1. Am I now only inputting 3 watts instead of 4 watts (because as we know,a 3:1 loses 25% of power). Should I put like a maco match box between the radio and amp? Of course this is for only theoretical conversations. Thanks. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1519
Registered: 9-2004
| | Posted on Friday, May 05, 2006 - 12:13 am: |
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what 833 is saying is that there is an impedance mismatch between the radio and the amp.
say the radio is putting out 50 ohms, and the amps input is not 50 ohms.
yes, some of the power coming out of the radio is being reflected back into it.
do not put a match box in line. it will only fool you into thinking you've fixed the problem.
what you need to do is find out if your amp has variable input tuning. (most CB amps dont)
it will be a trimmer cap on the input side of the amp.
some also have output tuning so you can tweak the SWR coming out of the amp too.
if your amp does not have the input tuning adjustable, try going to the "modifications" section, under "amplifiers" and go to the thread titled, "amp mods 101"
ask Georgeodjungle if you can add variable tuning to your particular amp.
it would entail removing a cap, and replacing it with a varable cap.
good luck,
matt |
Tech833
Moderator
Username: Tech833
Post Number: 1346
Registered: 8-2002
| | Posted on Friday, May 05, 2006 - 9:50 am: |
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"Well, for theoretical reasons, let's assume it is being used on 11 meter. "
Then I must respectfully withdraw from this conversation. |
Jameslarson
Intermediate Member
Username: Jameslarson
Post Number: 108
Registered: 4-2006
| | Posted on Friday, May 05, 2006 - 10:15 am: |
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My mistake. I should have wrote "informative" reasons. OR "educational" reasons. or "Scientific" reasons. Thanks. |
Dale
Intermediate Member
Username: Dale
Post Number: 362
Registered: 12-2002
| | Posted on Friday, May 05, 2006 - 11:02 am: |
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well some say coax lenth matters some say it doesnt .if it doesnt then why are jumpers sold in 3ft lenths3,6,9,12,ect .assuming that it does
matter then a fullwave lenth is 36ft ,and 1/4 of that would be 9ft 1/2 would be 18ft,ect so if i
was told 2 get coax in 1/4 muliples it would be
in mutles of 9ft.or if i was told 1/2wavelenths
i would need 18ft.im not saying coax lenth matters or not but im was wondering about if i got the wavelenths correct.ive never worried about coax lenth before but after readibng these
posts im begining 2 wonder as ive had swr issues in the past but been able 2 correct at the antenna.im sorry as im stupid in this area
dale/cef426 |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1526
Registered: 9-2004
| | Posted on Saturday, May 06, 2006 - 11:12 pm: |
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tech833, HAS to withdraw from any conversation that could be construed as him giving illegal advice.
its not only his ethics, he has signed papers saying that he wont.
he is very highly regarded in the broadcast industry and cant afford to take part in these shady conversaions.
as for his opinion of people using amps on CB; well, i'll leave that for him to say!
so dont take it personally, he's upholding his license.
now, ask him anything you want about antennas!!!
matt |
