Ianf406

I could link THOUSANDS of pages that disagree with you like this one-
https://books.google.com/books?id=wU...20myth&f=false
This one...
http://www.qsl.net/v73ns/swr.html
This one... Which is pure SCIENCE
http://techchannel.att.com/play-vide...-Wave-Behavior
Some more...
http://forums.radioreference.com/cb-...vs-signal.html
http://www.thetruckersreport.com/tru...x-coil.135556/
http://www.radiomods.co.nz/coaxlength.html

But hey, to each their own. People still think you cant eat before you swim, cracking your knuckles will give you arthritis, toads give you warts, gum takes 7 years to digest, and carrots improve your vision science and all. You want to have a coil of extra cable in your Jeep? Go for it. My setup works fine without it.

Fred/N0AZZ

With that type of antenna 18' of coax is not required because of the way its loaded you can cut it. Let us know what you find out.


The one thing you failed to link to were any Amateur Radio or ref. concerning antennas the same theory applies to them all not just a CB. CB generated more myth's than anything for sure by people who knew very little about radio in general. I know I bought my first CB in 1974 and picked up many of those myths in those years, later to be debunked by study and 3 yrs of collage electronics theory and adv. math late in life for the love of a hobby one I embrace a lot and try to help others with to enter into.

toasterknight

As a licensed radio operator myself I have to second Fred's argument. Feed line length has no effect on swr. Unless it is frayed and grounding out on something.

Bugout4x4

Don't know if he was right or not? but my old radio and computer guru friend who worked on and designed communications for the Government and Military explained to me one time that a feed line should be cut in increments of the wave it will be used for. If the wave is 36' ft then it should be cut in divisions of this length, Matched at 36', Half wave length at 18' or quarter at 9 ft or even just trimmed in 3' and 1.5 ft increments for optimal output performance as long as it was an even division of the wave length. Now this guy knew what he was all about with everything else he did. He worked for IBM when they had the huge mainframe computer, 22" hard drive disks and tape drives. He helped design and set up the computer monitoring systems for Edison's Laughlin power plant when they built it.


I have trouble thinking he would have steered me wrong about this importance?

Fred/N0AZZ

No not quite correct some antennas do require that length of coax my 102" whip with a 6" spring "Does" need that coax length to load for it to make a 1/4 wl this only applies to mobile installs. At home use ground radials cut to length to make the length come out properly on HF vertical antennas. I have some coax that are 50' up to 250' in length from antenna to the shack.


Bugout 4x4 was correct on the math on that one.

Ianf406

Hey fred, I meant no disrespect or anything. You have been working with them longer than ive been alive. All i know is that in my personal experience, the quality of the pieces used matters more than the length of cable. Everything I've ever read or been taught about wave lengths with any scientific backing has been contrary to the 18' thing.

I will say that when we do the annual 4x4 cb tune up, we have noticed that a SWR Meter is fairly inacurate and prefer to use a analyzer... even moving the cable inside the vehichle will drastically change the reading on the meter. Using the analyzer, I have found that length of coax matters little. Mounting location, quality connections/coax and a tuned tip make all the difference.

I told mythbusters to give this one a crack.. doubt they will but would be interesting haha

Fred/N0AZZ

I understand completely and bought into a lot of things back in the 70's about CB and antennas found out in later years not to be true.


I also use an Antenna Analyzer for all measurements but it depends on the impedance of the antenna and type. Mounting position has a great deal to do with overall performance of the antenna and radio.

SeriousOffroad

Update?

crawler487

Sorry guys this weekend was a disaster of broken vehicles in my family so I didn't get a chance to finish the antenna. I plan to get to it tomorrow. Sorry for the delay.

crabmushrooms5

Another thing to note, that shoulder washer should be inserted with the inner lip pointed downward. Took me from swr off the charts to less than ~1.5 when I put mine on my truck. I guess I wasn't paying close enough attention when I put it together

crawler487

Alright. I had a chance today to look into it and do everything that everyone said was wrong or I at least needed to check. This includes wrapping the extra cable in a figure 8 and tied in the middle, I checked that washer and its installed correctly now, I also made sure my antenna mount had a clear path to ground... and as of now I have a higher swr in channel 1 than I do in channel 40. Around 3.5 on channel 40 and about 3.9 on channel 1. From what I understand, that means that there is either a short or the antenna is too short. I did check for a short throughout the Coax and there isn't, but it was reading about .5 ohms on the center pin of the coax(from the radio end to the antenna end) on my fluke multimeter. So I'm not really sure where to go. Let me know what you guys think. Thanks!

toasterknight

How much adjustment do you have in the antenna left over?

crawler487

None, I had it all the way out.

toasterknight

Try moving it in. It may help. Worst case it makes it worse and you figure something else.

crawler487

I thought the exact same thing earlier lol and nothing changed.