| Author |
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JMB
| | Posted on Wednesday, October 30, 2002 - 3:08 pm: | 
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I am confused, I always thought SWR stood for (S)tanding (W)ave (R)atio but I frequently see it referred to as SWR's. Is there more than one Standing Wave Ratio? |
sandbagger #106
| | Posted on Wednesday, October 30, 2002 - 5:18 pm: |
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As far as I know VSWR and SWR are one in the same.The V stands for voltage. SB #106 |
Scrapiron63
| | Posted on Wednesday, October 30, 2002 - 5:49 pm: |
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haha, funny funny. You hear all kinda stuff in and around the CB band. I think the old AM CB lingo is funny sometimes, kinda stupid, but funny, I've known CB'ers that had a 'radio' voice, it would be completly different than their normal talk. You meet them in person, and wouldn't recognize their voice. But its the wannabe hams trying to talk sideband up in the free band that gets to me. They try to 'Q-code' everything to death, and don't know what the heck they mean. I heard one today, he was QSK'ing about every 3rd word, then he was "QRT" on the side listening, huh? Guess he was 'on the side listening' twice. ha
Oh well, its mostly newbe's, after a while, most learn they can talk on the radio like in person or on the phone, don't have to 10-4 or QSK every other word, and even without echo or roger beeps. |
deadlyeyes
| | Posted on Wednesday, October 30, 2002 - 7:44 pm: |
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Re SWR....
Nope there is just one. The plural is way of saying the measurement is greater than a 1:1.
Here is what SWR is for those who do not know. Three things you have to remember. The feedpoint reactance of an anetnna can be represented as the equal of a common carbon resistor. The charastic impedance of any coax can also seen as an equal valued carbon resistor. Lastly, for the maximum amount of energy to be transferred from one stage of a circut to another stage of a circut the output of the sender and the input of the receiver must have exactly the same reactance or resistance value. If there is any difference some of the energy will be lost in the inbalance. I simplified to avoid going into too many details.
Now back to antennas and SWR. If your antenna feed point resistance is say 70 ohms. Your coax lets say has a 50 ohms resistance value. Your radio has a 50 ohm output resistor value. The energy flows freely from the radio to the coax without too much being lost to any missmatch. BUT at the antenna the resistance is 70 ohms. The resultant proper SWR between the antenna and the coax should be about (70/50):1 or between 1.4 to 1.6 : 1. Remember you also have to add on some resistance due to soldering and such, just a little bit.
May I strongly suggest you order from our good host a cross needle SWR Meter. One needle will show you your power output while the other will report the power lost to SWR which us usually indicated on the reflected needle scale. The best meter is one that measures both/gives you the option of Average and Peak power. |
Insider
| | Posted on Wednesday, October 30, 2002 - 7:48 pm: |
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Usually people pluralize SWR because it sounds nice that way.
There are actually two SWR parameters that can be measured: Voltage Standing Wave Ratio (VSWR) and Current Standing Wave Ratio (ISWR). When people talk about SWR, they are referring to the Voltage Standing Wave Ratio 99 percent of the time because most SWR bridges measure reflected voltage.
Now I'm not certain about this, but I've heard the coax lenght trick cannot fool an SWR meter that measures current. Perhaps one of the techs could comment on the validity of that. |
Taz
| | Posted on Wednesday, October 30, 2002 - 9:19 pm: |
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I use 10-4 about once a month weather I need to or not. |
bruce
| | Posted on Wednesday, October 30, 2002 - 9:29 pm: |
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Its VSWR but thats no big deal now as for coax i test mine by hooking a dummy load to it and seeing if my watt /VSWR meter reads near zero. Intresting how many peices of OLD coax is no where near 50 ohms |
HoosierCardinal
| | Posted on Thursday, October 31, 2002 - 6:43 am: |
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Amen Scrappy!
I never hardley use AM talk or lingo on the CB and on SSB i just talk like i do when im on the phone or in person (but i try to watch the 4 letter words!LOL) |
123upmichigan
| | Posted on Thursday, October 31, 2002 - 11:34 am: |
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qrt and standing bye. what a pet peeve!lol every q code list i have ever looked at stated that standing bye was qsx. not every person i hear in dx is sayin i'll be qrt and standing bye.. now how can they be standing bye if they are off the air? I have been complaining to people for it just about every night. well take it easy 123
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Kb5lpa
| | Posted on Friday, November 01, 2002 - 10:34 am: |
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I agree with HoosierCardinal....talk just like you do in person. No need to say things originally intended for cw on voice. It is amusing, though, to hear "QRT and standing by." Visions of a guy standing by a radio that he just turned off(!) always seem to make me laugh.
73 de KB5LPA |
Galileo
| | Posted on Friday, November 01, 2002 - 9:12 pm: |
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I like the guys that say QSL, at the end of every transmission.......Hahahaha...Cracks me up..... |
bruce
| | Posted on Friday, November 01, 2002 - 9:19 pm: |
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MY pet peve 73's 88's or as good RST 599 on FM and the never fails Your 5 BY 9 ?????
RST (Readabilty Strength Tone) A CW relic from the days of spark gap USELESS on Am or ssb
And 88 not 88's 73 not 73's.... Realy im not being picky another CW left over.
Bruce |
Marconi
| | Posted on Saturday, November 02, 2002 - 1:12 am: |
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Hey Bruce, you said the following: "Its VSWR but thats no big deal now as for coax i test mine by hooking a dummy load to it and seeing if my watt /VSWR meter reads near zero. Intresting how many peices of OLD coax is no where near 50 ohms."
That may be true, but you might also be surprised how many dummy loads aren't 50 ohms either. Among the several DL's that I have, only one shows 50 ohms over a good portion of the bandwidth it is supposed to cover when hooked up directly to my analyzer with no jumper. On the other hand, this one also shows some reactance that you would think should not be there.
I have a 52 ohm load that reads about 46 ohms when hooked up directly, with no lead, and it shows no reactance over the entire frequency range of my analyzer, but it is not right on the 52 ohm mark. I figure I can compensate for that error.
I understand that the more resistors there are that make up to 50 ohms, the better the chances of getting a true 50 ohm reading, but the many resistors can present reactance problems by the many little connections to some extent, so there you go.
I am not too sure how well this can be detected with just an SWR meter. You should see what happens when you start testing different lenghts of line using an analyzer and a dummy load. I am not sure what a high dollar testing device would show, but that is what I found using my little Autek.
Marconi |
Marconi
| | Posted on Saturday, November 02, 2002 - 1:20 am: |
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Try this CB Sideband language on for a little irritation. A fella in Europe is always saying "Cheer's & Beer's" about every 10 words.
How do you like that one, good buddy? How did we get off on this topic?
Hello Tom.
Marconi |
bruce
| | Posted on Saturday, November 02, 2002 - 7:05 am: |
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Marconi your right but i only comented on the silly use of 3's 8's as for dummy loads sure they may not be flat one reason haveing access to very good equptment at work gives me the chance to check my own stuff. As a rule old coax ....and even some cheep new stuff is not 50 ohms now not only do you have the antenna going away from 50 ohm as you move away from resonance. I had axsess to a time domain meter one time and a 50 foot peice of coax was a nightmare it would vari from 45-65 ohms depending where you were so i but several rolls and tested them before using that run for my 220 mhz beams. At work we use THOUSANDS of feet of LMR-400 cable on our 460 meg repeaters and it has worked out very well untill our new repeater room is built our repeater is 800 foot from the antenna and we have a number of them. That cable for cost has worked very well but not to say other cable might not work well too.
Bruce |
Bigbob
| | Posted on Saturday, November 02, 2002 - 6:14 pm: |
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Man you guys are wall to wall and tree top tall,10-4 good buddy? oh my gawd that was awful,yeck.Hey marconi why don't you loan xlaxx your analyser,but first show him how to use it,then he could figure out his problem. |
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