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Road
Junior Member
Username: Road
Post Number: 12
Registered: 11-2007
| | Posted on Sunday, December 23, 2007 - 1:27 pm: | 
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Having a ground problem getting perfect swr's on the big truck.I had 1.5 swr's so I ran a ground wire from the antenna to a bolt on the mirror bracket and am getting higher swr's. If I grab the bottom of the antenna when keying the mic I get 1.1 swr's which is telling me it is a ground problem. should I try running a ground wire all the way to the neg terminal on the truck or just try grounding to a bolt on the chassis of the truck instead of the mirror bracket? Or could it be the mounting hardware? any opinions are appreciated thanks. -Road- |
Moderator136
Moderator
Username: Moderator136
Post Number: 617
Registered: 4-2005
| | Posted on Sunday, December 23, 2007 - 6:54 pm: |
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Try ground wire to chassis of the truck. Hope this helps, Let us know what you come up with?
Hal ~ Moderator136 ~ KCØSVC
CEF#136/CEF HAM#23 ~ CVC#004
Moderator136@copperelectronics.com
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Captian_radio
Intermediate Member
Username: Captian_radio
Post Number: 293
Registered: 9-2004
| | Posted on Sunday, December 23, 2007 - 11:18 pm: |
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When you touch the antenna and the swr drops it usually indicates that the antenna is to short or too long for the freq.,when you move close to the antenna like that your body is making the antenna look longer(inductive) or shorter(capacitive)with your body acting as part of the ground plane.Don't use just a piece of wire but use a piece of braid such as found if you strip away the outer insulation from a piece of RG213 coax.RF ground is different than electrical ground, as RF needs a larger surface area to flow properly.
Bob CEF451/VE1CZ
Robert L. Spicer The days of radio are just beginning!
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Streaky
Intermediate Member
Username: Streaky
Post Number: 154
Registered: 3-2006
| | Posted on Monday, December 24, 2007 - 11:20 am: |
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Try aground strap from the door to the truck chassis and make sure you have good conductivity
Streaky
CEF #805
CVC #98
The craziest station in the Canadian nation
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Road
Junior Member
Username: Road
Post Number: 13
Registered: 11-2007
| | Posted on Monday, December 24, 2007 - 5:24 pm: |
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Thanks, I appreciate the input. I will let you all know the outcome. I won't be back to work until after New Years so I will let you know then. Thanks and Merry Christmas! |
Gumball
Member
Username: Gumball
Post Number: 53
Registered: 10-2004
| | Posted on Thursday, December 27, 2007 - 1:22 am: |
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Complete the picture - ground strap from the antenna mount to mirror bracket, make sure mirror bracket has a good contact to the door, ground strap from door to chassis (hinges do not make good contacts), ground strap from chassis to frame. |
Hotwire
Senior Member
Username: Hotwire
Post Number: 2449
Registered: 1-2005
| | Posted on Sunday, December 30, 2007 - 12:44 am: |
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Anytime you change something on the antenna you MUST recalibrate the SWR meter. So if your keying the mic and the meter indicates an swr of 1.5 then you grab the antenna of course the meter reading is going to change! Does not mean anything is wrong, besides your hand grounding out the antenna. Maybe with your particular setup and vehicle with fiberglass body an SWR of 1.5 is the best. Nobody will ever know the difference in performance EVER. An SWR of 1.5 is fine, just talk! BUT if your losing sleep over it just adjust the length of the antenna until the meter makes you happy. Your at 1.5 now so no extra grounds are going to help much if at all. May even have to try a different antenna to get a better match.73
KEEP IT REAL!
Kenny
cef491(27.115lsb)
2sf491(27.555usb)
Indiana
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Lester_elm
Junior Member
Username: Lester_elm
Post Number: 11
Registered: 12-2007
| | Posted on Sunday, December 30, 2007 - 7:15 pm: |
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I agree with 'Hotwire' on this one. As a matter of fact, an SWR 2:1 is perfectly acceptable on CB (contrary to what we have all been told). Anyone on the receiving end won't be able to tell a difference in your signal whether your SWR is 1.1:1 or 2:1 on a moble setup. Now if your antenna was in the air, say 100 ft, then that would be a different story. Adjusting the antenna length is the only way of adjusting your SWR. In effect, that is what you are doing when you touch the bottom of the antenna. You are not changing the physical length, but the electrical length.
CEF #964
HAM #276
Ham Radio - Talk worldwide on a tin can and a wet noodle
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