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rock jack
| | Posted on Monday, September 08, 2003 - 3:24 am: | 
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Just a few questions? One, what good is grounding a antenna? Two, does grounding help with TVI? Three, does grounding help with static on your radio? Four, what are some good ideas to get a good ground? |
radiodude
| | Posted on Monday, September 08, 2003 - 7:53 am: |
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I think this may help you
1. The Antenna is 90% of the system operation, this includes the coax and connectors.
2. Grounding on your Basestation:
a) Use 2 of 8-foot ground rods driven into the earth about 8-feet apart.
b)Using clamps attach #4 or #6 copper wire
(7-strand or less) to the rods or 3/8 copper tubing.
c) Attach this wire to the radioand power
supply, filters etc.
d) Do not use "braided" wire or coax "shield" wire as a ground cable.
e) Grounding is very important for all transmitters, whether they are 5 or 100 watts.
3. Low Pass filters in the antenna coax line.
Are used to eliminate TV Interference.
Must be grounded as above.
4. Mobiles,
a) Antenna placed on the roof is best !
b) Antenna that is 9-feet for CB is best on mobiles !
c) Antenna of 3.5 to 4 feet is the smallest you should use.
d) Mirror mounted antennas are not good, because there is no ground plane under the antenna !
e) Antenna mounted on side of front hood, well forward from metal windshield posts are good !
f) Antenna mounted down the side of vehicle beside metal won't work well on transmit.
g) Match and tune required on all antennas
or the radio will transmit out poorly !!
h) Ignition Noise: Popping sound while receiving: -keep antenna back and away from the motor. -bond the hood to the firewall with wire straps (two sides) -turn of the ANL (automatic noise limiter) or NB (noise blanker) on the radio.
i) Alternator Noise in receiver:
-"whiring" sound in the receiver.
-rewire radio directly to the battery (add fuse to +12 volt wire and ground wire at battery.) -cut and add filter to +12 volt wire. (capacitor and inductor filter)
j) Noise from windshield wiper, fuel pump, heater motors: -cut and add filter (capacitor and inductor) to the wires from the motors at each motor.
5. Basestations:
a) Antenna of 9-feet (1/4 wave) requires 4 of horizontal 9-foot ground planes (grounded to coax shield)
b) Antenna of 18-feet (1/2 wave) does not require ground planes.
1/2 wave antenna has 3-db gain (double power and receive) as compared to 1/4 wave antenna.
c) All antennas have to be at least 1/2 wave (18 feet) away from all metal verticle surfaces and wire objects.
This metal can be below the antenna but not above the coax feed point on the antenna.
d) Yagi antennas will give a large increase in signal strength.
Because they are directional, they will require a rotor to point the antenna in the correct direction.
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Rfman100
| | Posted on Sunday, September 14, 2003 - 1:38 pm: |
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What if you live in an apartment bulding
and you do not have a backyard with dirt.
with an atenna stick out of your window?
And all you have is a radiator or water pipes?
How do you ground? |
Bruce
| | Posted on Sunday, September 14, 2003 - 2:18 pm: |
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to the pipe |
Tech833
| | Posted on Wednesday, September 17, 2003 - 1:27 pm: |
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Water pipes make good grounds. Not perfect, but good. |
Crafter
| | Posted on Wednesday, September 17, 2003 - 4:27 pm: |
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Water pipes do give you good ground, warning though pay attention Natural gas pipes should not be used. |
Reno
| | Posted on Saturday, September 20, 2003 - 11:36 pm: |
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Hello Rock jack. Grounding can be a very contravesial subject. First of all grounding your antenna is a good idea for aluminum antenna's to protect your house against lightning.There are some very good lightnig arrestors on the market for coax installations. As far as helping with TVI grounding can do some harm. Remember your cable,telephone and house wiring is also grounded. So if you ground your coax or radio to the same ground and you already have a problem with TVI it could make it worse. Remember the earth is not some substance that just magicly obsorbs magnetic waves. I would like to suggest to you to obtain a ARRL hand book. It has a lot of information on TVI and proper staion grounding. Hope this was some help for you,,,Reno |
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