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whats your ball for? ANSWERED

Fordum

Fordum

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Ok folks, here is one for you. I just got through explaining this to a friend of mine down in the swamps. The river level finally went down enough for us to get to our camp, so I will be in the swamp for the next few weekends.

Anyway, here is a question for all you young whippersnappers. ( I have always wanted to use that phrase. I'm not quite old enough for it yet, but I'm working on it.)

What is the purpose of the ball or knob on the end of your am/fm antenna?
I suppose it is partally to keep it from putting someone's eye out, but it actually serves a necessary purpose beyond that. In fact, without it, your radio will not work as good, and maybe not at all.
If there are any old ham radio people here, they might know the answer, but otherwise I doubt anyone here has heard of this.
Give me your best guesses, and I will post the answer tomorrow after I get out of the swamp. Plus show you a cool way to demostrate what I am saying is true. Well, some of you will be able to do the demo, others will have to wait a few months.

J.
 
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Not sure what its for but when it take a hit of lightning its toast.

In my particular episode, the lighting traveled down the antenna, smoked the radio, map sensor, computer and put 6 small holes in the right front tire.

The little ball was the first victim on its path.

I'd be interested in the answer as well.
 
Fordum said:
Ok folks, here is one for you. I just got through explaining this to a friend of mine down in the swamps. The river level finally went down enough for us to get to our camp, so I will be in the swamp for the next few weekends.

Anyway, here is a question for all you young whippersnappers. ( I have always wanted to use that phrase. I'm not quite old enough for it yet, but I'm working on it.)

What is the purpose of the ball or knob on the end of your am/fm antenna?
I suppose it is partally to keep it from putting someone's eye out, but it actually serves a necessary purpose beyond that. In fact, without it, your radio will not work as good, and maybe not at all.
If there are any old ham radio people here, they might know the answer, but otherwise I doubt anyone here has heard of this.
Give me your best guesses, and I will post the answer tomorrow after I get out of the swamp. Plus show you a cool way to demostrate what I am saying is true. Well, some of you will be able to do the demo, others will have to wait a few months.

J.
Click to expand...

I'm no expert but isn't it to prevent the radio from shorting while on? as in preventing it from touching metal such as the car or other object?
:dunno:
 
im gonna guess it has to do with receiving the signal..

antennas catch the radio waves, but it seems to me that a straight pole is only going to catch waves from side to side, while the ball on the top lets them grab from all angles?
 
I never really thought about it, but I'm assuming its a similar deal as with electricity, where more current can be stored. Whereas a sharp point allows for a rapid discharge because no electricity can be stored (thats why stun guns have pointed metal pins).
Is it something of that nature?
 
I don't want to ruin your thread since I cheated and googled it but it's quite interesting! :)
 
I've always heard it is to keep it standing up straight. You know when you drive down the road, the antenna spins in a circular or figure 8 motion. My Dad and Grandpa were hunting and Dad's little .17 jammed. Grandpa pulled the antenna off Dad's old LUV truck and popped that little ball off the antenna so they could remove the hung up bullet. Dad said on the way home, the antenna was laying back and not spinning. Since the ball was lost to the grass, he bought a new antenna for it and we still have the old one in the gun cabinet.
 
I know my dad (ham radio guru) has told me this before, but I don't remember:doah: I guess a phone call is in order.

EDIT Ok, I know the answer
 
Nothing electrical, it's purely mechanical. Acts as a vibration damper -- as mentioned, to keep the antenna from flailing around and breaking.

-- A
 
mainly to help dissipate any static electrical charges generated as the antenna is moving thought the air.

The ball at the tip of an antenna is a "corona ball"
 
Right, but from the wrong angle.<G>.
Static electricity will "leak off" into the atmosphere at a lower voltage from a small surface area than from a large one. That ball on the end of the antenna made sure that it would take a higher voltage to bleed off there than somewhere else on the car.

That is why a Van d Graff generator has that big ball on top. To let the charge build up higher.
While a car builds up a charge moving through dry air, it builds up even more from the tires rolling on a dry surface.
Ever notice how some cars will shock the sh*t out of you when you go to get out on cold dry days and others won't?

Most of the time you can blame the tires. Some makes and models have a greater amount of carbon black and other partially conductive stuff in them that lets the charge bleed off faster than others.

Back in the old AM days, this kind of stuff was really important. In fact, they used to sell graphite to put inside the tires to try to cut down on static buildup.
I never was sure how effective that was.

Anyway, since everyone was using AM, any static that got close to the antenna caused the radio to become useless.
A favorite trick among hams was to slip up and cut the little ball off the antenna when the owner was not around.
The resulting sharp point would cause the naturally occurring static electricity to discharge through the top of the antenna instead of whatever sharp place it normally did. This caused tons of static and weird howling sounds and pretty much shut down any radio listening.

Since FM naturally filters out any voltage spikes and Am type noise, that is not noticable much anymore. However it is still there and can cause an FM radio to not be as sensitive as it would normally be.

If you want to see how much charge is built up, there is a little trick you can do.
BE CAREFUL, its not too dangerous, but if you let the wire get too long, it can get under a tire and get snatched out

All you need is an insulated wire that you can strip the ends back on and let hang out through the door jamb. One end should be stripped back pretty far, and should be allowed to drag along the pavement. The other end should be placed a small distance from a ground in the cab.

Make sure it is not close to any electronics equipment, since several hundred volts will be on the wire.
Drive along a dry pavement at night and watch for the sparks. I have gotten almost an inch long blue-white spark on cold winter nights.
And yes, it will give you a jolt if you reach down to adjust it without stopping like I did.
BTW, if you are someone you know is getting shocked when they get out of the car, and you do not want to install some kind of static discharge thingy, tell them to hold a piece of metal in their hand and touch it to the door handle or whatever part of the car that shocks them.
It is not the static charge rushing into them that stings, its the little spark its self when it hits their finger. If they use a key or some kind of metal to take the spark, they will not feel the shock.
Cheaper than buying new tires.....

J.
 
I remember when the fuel delivery trucks had a piece of chain bolted to the frame and dragging on the ground to bleed off static electricity. It must not have been too important as I've not seen them for years.
 
driney said:
I remember when the fuel delivery trucks had a piece of chain bolted to the frame and dragging on the ground to bleed off static electricity. It must not have been too important as I've not seen them for years.
Click to expand...

I remember that too. Better tire technology now?
 
Most natural gas vehicles still have a hanging rubber/metal strip as a ground.

All the CNG busses around here have them.
 
we've had a few fires here at work from static electricity caused from transfering solvents and not having the hoses grounded. We also had a huge filter catch fire, when the solids were being shoveled out with a stainless steel shovel, and they scraped the stainless steel filter screen in the bottom of the filter housing. The solids were washed with a solvent, then dried with nitrogen for 6 hours prior to being shoveled. So just be sure you ground any liquid transfer you have going on. Even from a gas can to a lawn mower, there is a chance of static build up.
 
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