Stinger length

[frmboybuck]

Does anyone have the general stinger length for a single coil 10K with a 12" shaft? If not, how about overall tuned length?

 

[jessejamesdallas]

The stingers that come with the Single Coil 10K's are 63"...And you will need to trim some off to tune the antenna...After the antenna is tuned, the "Over-All" height can vary from 65" to 75" (or taller)...Just depends on where you mount the antenna, and the coax length and type.

 

[BOOTY MONSTER]

how does coax length affect antenna tuning length ?

 

[Marconi]

how does coax length affect antenna tuning length ?

BM, this has been my experience. If the antenna is tuned perfectly at resonance and shows no reactance, then you will not likely have any transformation in the system and the feed line will appear transparent to the system. Of course the connectors have to be perfect too.

In most cases this does not happen and the feed line will be somewhat reactive. A lot depends on the amount of reactance at your choice of frequency (center) and then the feed line will become a part of the radiating system and then to some degree the longer the line the longer the radiator will appear and the lower the frequency. I am not sure if this condition is linear curve (/)or takes the form of a sinus curve (~).

Line theory is complicated and there is more to this issue, but that is my short story.

 

[jessejamesdallas]

BM...Example...If you tune your antenna say using RG 58 coax, then later decide to change out the coax to something like LMR 400, and you cut the new coax to the exact same length as you had before, then if your using a Antenna Analyzer, you will see that your SWR has changed, (it will probably read differently on a regular SWR Meter too, but I always use a Analyzer, so that's what I'm basing this on) and you will need to re-tune the antenna...IMO, this is because the velocity factor of the two coaxes is different, and the resistance has changed so the same length of coax is not going to give you the same reading...

 

[Marconi]

Hey JJD, that kind of makes the calculator that you post in another thread for how long your feed line needs to be just another CB BS story, right? This is also not what frmboybuck asked about any way. BM injected this idea.

 

[mackmobile43]

Does anyone have the general stinger length for a single coil 10K with a 12" shaft? If not, how about overall tuned length?

I have that setup on my car with a tri-magmount but I don't have access to my car for a few days but when I do I will get that measurement for you.

I have one hanging in the garage from a mirror mount setup from a semi-truck I used to operate and the stinger length from it is 51'' total length which includes what is inside the top section which is 6 or 7'' give or take.

Without knowing your setup it would be hard to guess if possible at all but those are the numbers I have.

 

[frmboybuck]

Thanks guys....this is on a 379 mirror mount.

 

[jessejamesdallas]

Hey JJD, that kind of makes the calculator that you post in another thread for how long your feed line needs to be just another CB BS story, right? This is also not what frmboybuck asked about any way. BM injected this idea.

Shhhhhhhhh.............that was suppose to be a secret.

 

[mackmobile43]

Thanks guys....this is on a 379 mirror mount.

My measurement should get you in the ball park, just cut it a bit longer and go from there, like my pappy always use to say "he cut it twice and it was still too damn short"

 

[BOOTY MONSTER]

BM, this has been my experience. If the antenna is tuned perfectly at resonance and shows no reactance, then you will not likely have any transformation in the system and the feed line will appear transparent to the system. Of course the connectors have to be perfect too.

In most cases this does not happen and the feed line will be somewhat reactive. A lot depends on the amount of reactance at your choice of frequency (center) and then the feed line will become a part of the radiating system and then to some degree the longer the line the longer the radiator will appear and the lower the frequency. I am not sure if this condition is linear curve (/)or takes the form of a sinus curve (~).

Line theory is complicated and there is more to this issue, but that is my short story.

so with a less than perfectly tuned antenna the coax can become part of the antennas radiating system and throws the vswr off .... correct ? assuming properly constructed coax .

that makes sense . seems related to how some amps have to have a certian coax length because they are not properly tuned to a 50 ohm load . both examples of coax length affecting vswr fecause or a less than perfect vswr/ohm impedance at the end .
but it does clash with coax length supposedly suppose to not affect vswr .

 

[W5LZ]

Booty M',
"but it does clash with coax length supposedly suppose to not affect vswr"

Ah, but that not affecting SWR because of length has a 'catch' to it. That catch is that the load/antenna on the end of that coax is resonant and properly matched to the feed line's impedance. If the antenna's right, feed line length just doesn't matter.

Hang on, it get's even better!
Because reactance changes with frequency, if that reactance is chosen correctly and put in the right place, the further you get away from a resonant frequency, those changing reactances can make the whole thing -appear- to still be resonant and impedance matched. One particular antenna type that comes to mind very quickly that takes advantage of that is a 'Bazooka', and there are others that are common on the CB market, the one's that appear to have a low SWR from daylight to dark, broadbanded like the devil! Why? Cuz they are -not- being 'measured' with a fool proof meter. Think about it...
- 'Doc