102' whip tunning

kc0iv · May 29, 2010

Carolina Thunder said: ↑

I know that,you know that and most other people know that but since i use a MFJ digital SWR meter to tune my antennas......i will just go along with what it says and shows that the 21 feet of coax brings the SWR down to below 1.5. when 18 foot is always over 2.0 no matter what i do. I still wonder is the length of the coax some how changes the wavelength when used with the steel whip and that's why the SWR comes down but i don't know. Antenna theory has never been one of my strong points.

Oh and I'm of the mindset that the length of coax does not matter as long as it is done in 3 feet increments ( 18 ft to 21 ft and so on ) that's the way i have done it for years and have yet to have an excessive reflection problem and i measure that by using a bird meter with a 5 watt slug turned backwards. If there is any reflected power coming back into your radio i promise you will see it with a bird
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1. The frequency of our CB signal is 27.4 MHz (somewhere around the middle of the CB band).
2. The wavelength (in feet) of our CB signal is 36 feet.
3. A half wavelength is 18' and a quarter wavelength is 9' (or 108").

Where people get in trouble is they don't account for the velocity factor of the coax. As an example that 18 foot coax people tell you to use does not take into account of the velocity factor. Looking at Belden RG8X Coaxial Cable it has a velocity factor of 0.66. If you take the 1/2 wavelength you have a figure of 11.9 feet.

Now about SWR meters and even Watt meters. To use it properly you should have a coax cable that matches the meter impedance. And have a length equal to 1/2 wavelength times the velocity factor of the cable.

I would recommend anyone wanting to know the true facts is get an "ARRL Antenna Book" or William I. Orr (W6SAI) antenna handbook. One can all so go the the public library. Most have the "ARRL Antenna Book".

I would also recommend http://www.stu-offroad.com/misc/myth-1.htm for a more detail look at the coax myth.

Another good site is http://www.shadowstorm.com/cb/CB_Myths_Exploded.html

Yet another http://www.signalengineering.com/ultimate/coax_basics.html I like this site.

Doing a google search will show many more CB myths on coax and antennas.

Leon
(kc0iv)

WA4GCH · May 30, 2010

kc0iv said: ↑

Isn't the 12avq a base loaded triband antenna with a tapped feed coil?

BTW seems like an expensive way to create a ground plane.

And if I recall the CAABC23 is a 5/8 wave antenna which would also require a matching network.

Leon
(kc0iv)
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The 12avq is a 1/4 wave end fed that requires a ground plane system and mine is more than 20 foot off the ground. The HAMSTICKS were not cheap but how else do you get a self supporting groundplane that high up ?

CAABC23 is (3) 5/8 waves stacked 14 foot tall on 146 mhz it has its own ground plane.

BTW I use a noise bridge to set the 12avq on each band the SWR tracked the noise bridge just fine .....

SoulSeeker · May 30, 2010

After I got my kl-203 the out put wattage is around 70 watts for whatever reason it lost 30 watts, is this good for that amp on my uniden 520xl, I got some mix reviews from drivers giving me feedback some said that in their watt meter I wasn't coming in big and others said I was, but overall the responses were positive, they told me I sounded like a big radio despite the fact it is a small radio, I was averaging 3-5 miles solid like sounding like a big radio in the city, at night I was getting 5-10 miles, towards the 10 mile range it was getting fuzzy all this was in the city.

I hope 70 watts is good compared to 10 watts I had before, all this is connected to my lil wil, I will take this set up on a highway trip and post the info up.

I appreciate everybody typing their knowledge.

SoulSeeker · May 30, 2010

Big_m said: ↑

SS, a few people in here have givin you some of the best info in the world. They gave the pure truth about your antennas. 102" v.s. the lil' Wil. About your 1.1, -1.5 match. We have nothing to gain by lying to you. But your CB shop guy sure does. He's trying to get your money. I been on the radio since 1968. I've learned how to tune & peak them, and antennas. Fixed some, broke some. I install them mobile & base. All of my radios get out pretty good. Are they the best in the world NO! But they can be heard several miles away. Sometimes much more.

And I know that some others have said facts that you don't seem to want to hear. Try what was said to you by the many posters. And then you will have a very good sounding station. Run whatever makes you happy. Remember the Sun comes up every morning in the east. And it sets in the west. And it won't change just for us. Neither will the laws of 2-way radio & antennas. Things like your lil' wil gets out like your 102" whip. It just can't happen. No matter what CB guy told you it could. The 102" is the perfect 1/4 wave CB antenna weather the SWR is 1:1 or 1:5. Others are not. So will come close. But you will pay BIGGER bucks for them.

You have your radio, your amp, and antenna. You got the power to reach out and touch someone. Now go out and enjoy them.

Also look for a Good & Honest CB shop near you! Ask around. Ditch the CB crook!!!
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Ok well when I'm visiting the part of the map where you stay then I'll stop by and get a radio from you, I think then I will take all doubts I have and get a radio from somebody that will be honest, I think that sounds good to me what do you think.

SoulSeeker · May 31, 2010

I took my new amp on the road from Houston to San Antonio it wasn't bad I think it was better than before, but one thing is I can get out farther, but I can't receive that well.

I was talking to a driver he said after 3 miles I couldn't hear him, but he told me that I was still coming in loud and clear, but on my side it was big time fuzzy, but I think his system wasn't well set, because he told me he had a cheap cobra that wasn't working well and his swr was high, but he said for that small radio it sounded really good and clear.

Is there anything I can do to receive better besides mounting my 102'.

SoulSeeker · Jun 1, 2010

For example if I get a one of those CB that come from the factory with like 100 watts and I decide to put my kl-203 100 watt amp, will that do anything to the CB that comes with the 100 watts, will that add more amps at all.

Thanks For Reading

squirrellsgnwild · Jun 1, 2010

if you are to us a amp with a high powered radio you will burn up the radio.

SoulSeeker · Jun 1, 2010

squirrellsgnwild said: ↑

if you are to us a amp with a high powered radio you will burn up the radio.
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So it's better to have a low powered radio with a high power amp so it can work better.

High power radio with equal amp in/out put will burn radio.

If you got a high power radio can you still use a high power amp.

Big_m · Jun 1, 2010

SoulSeeker said: ↑

For example if I get a one of those CB that come from the factory with like 100 watts and I decide to put my kl-203 100 watt amp, will that do anything to the CB that comes with the 100 watts, will that add more amps at all.

Thanks For Reading
Click to expand...

Yes it will do something! SOMETHING WILL DIE!!! If you what more power out. You'll have to spend more money.

Big_m · Jun 1, 2010

SoulSeeker said: ↑

Ok well when I'm visiting the part of the map where you stay then I'll stop by and get a radio from you, I think then I will take all doubts I have and get a radio from somebody that will be honest, I think that sounds good to me what do you think.
Click to expand...

I'm not a radio shop or sales person. But I've helped some people install nice set-ups. But you can learn like I and so many others here have. It's very easy to do.

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