SWR vs Resonance

I'll look into the Stryker. On a unrelated note.Just plugged up an old Logitech PC speaker to my Cobra and I can't tell the difference between it and the heavy duty Wilson speaker. Needless to say. Im about to brave the cold and return this dang thing.

 

I had a Stryker before I traded it for the mirage not a expert like these guys but with just basic tuning it was better than most in the trk stop

 

Most likely the only diff is the ohm rateing on the two speakers...Both should be either 4 or 8 ohm but i dont remember which..Only problem is power draw and that will only be slight..

 

That's true and some of them make a really nice-big profit $$$ better to do research and order it on the web...

 

All quite interesting--and true! This is one of the beefs I've had with the CB "legend" of coax length being a cure-all. To those who say, "set SWR and hope for the best", I ask how you know that you are actually getting the best performance from your antenna? Just because the SWR is "low" it doesn't tell you if you are really getting the best signal out there. You could have a broad banded antenna with a low SWR and it is actually a poor performer over all! SWR is good. Everything "looks" good, the antenna "loads" up and the radio seems happy! What you might have is......a 'dummy load' on a stick! Take a 50 ohm, 10-20 watt resistor and solder it across a PL 259. Screw it into the back of your set. The radio will "load" all day long and be as happy as can be. Never mind nobody can hear you, but the rig sure is content! THAT is a traditional "dummy load".
Same way with antennas that are broadbanded (to get them 'extree channels'). They can be a sloppy radiator and a lousy performer. And you have no way of knowing if you are really getting all you can from your system. That's why the analyzer is so good because it tells you what your system really is doing. This matching, or feedpoint impedance can be very important. That's why you should tune/trim the antenna, not the coax. Like the coax voodoo, it shows (pretends) there's a 50 match (a measure of resistance). The radio doesn't care if there's a good signal--or no signal at all, but it cares if there is a mismatch. If there's a mismatch, this translates as heat instead of signal, and Mr. Heat loves to devour finals!!!

You can also think of it as "resistance": Something that "resists" a flow or a property. Picture a garden hose. Turn it on and let it flow thru the open end. Now take your thumb and "stop up" the end! This creates a resistance, or a back up. Stop it up enough to prevent the flow, and if there's enough pressure, POP! You get a leak or a busted hose! In the antenna system, when something is resisted, that is where heat comes in. Some resistance (impedance) is good. Too much creates heat. Make enough resistance, you can get things HOT, or even set something on fire! You ain't supposed to let the smoke out of your radio; its too hard to put back in!


In an antenna, there are 3 resistances: (expressed as ohms) Radiation resistance, COIL resistance, and FEEDPOINT resistance--or IMPEDANCE. As mentioned the radio likes to "see" an impedance of around 50 ohms; it doesn't care where it gets it from. Let's say radiation resistance is 10 ohms, coil resistance (you know, those big things truckers think makes 'em get out so) at 15 ohms, and the feedpoint impedance is 25 ohms--or thereabouts. Add it up. 50 ohms! That's not to say that its gonna come out exactly like that; its just an example to show how it works. In some cases, matching is not needed, especially at 27 MHZ. If so, well and good!
But this illustrates the argument FOR those big coil antennas-----NOT because they "get out better", but because of their size and turns spacing helps things out as opposed to one of those "fire stick" things where the coil is wound tightly around a small form. Cut one open and observe that coil made of thin wire. What does it remind you of? Makes me think of that HEATER I have under my desk to warm me feets!!! If it were possible on big rigs, ya know what would be the BEST all-round antenna? The 102" whip!!!! But we often must compromise using a coil to get the overall height down.

So if you are a stickler for "gittin' out", I wouldn't downplay the analyzer. Simply setting the antenna for the lowest SWR doesn't tell the whole story. However, OTH if, like one poster said, one is merely interested in talking and hearing 3-5 miles down the road, then by all means, set that and don't worry about it. If your "technician"(?) trims your coax and you are satisfied, hey, don't sweat it. Just don't put a whole lot of power in it if you ain't sure! POP!!!!!! (sniff sniff! I smell something burnin'!)

 

I have often said her swr is not a big deal...It is to a degree inportant but the GITTIN me out further inportant...
To much bs out there and to many tellin and repeatin what they hear and not know..
As good as it is to have a aa,that still doesnt tell all thats needed....I know all to well that an aa is only part of the set up....I know very little >-< << <------- thats how much i know but i do know its no where enough..My aa sez my radio is happy but because i dont know enuf theory my set up suxs dog poo...So now im changeing stuff and gettin a lil help here and there....Instead of a 5-8 miles i expect to stleast double it..Im determined to find a way without rippin apart the truck i dont own...Company doesnt want me doin all kids of stuff so im limited what i can do..

 

Gadfly's comment about the 50-ohm resistor brings to mind an article that ran in an April issue of the old S9 Magazine back in the mid-60s, describing the "Vampire Bat Antenna". This was when all things Batman were first becoming popular, and the article described the antenna with terms like "fantastic" (look up the dictionary definition), "perfect matching", "low-noise", "no-TVI", and my favorite.."the FCC would love to see all CB'ers using one." The construction details consisted of a bat-shaped piece of plastic with a big ole' 50-ohm resistor hooked across the feed point where the co-ax attached. Lots of guys suckered into building them.

 

God I remember that, the follow up letters were funny to read.

 

My dad used to call himself da batman on the radio...lol