| Author |
Message |
    
Bottle rocket (Unregistered Guest)
Unregistered guest
| | Posted on Tuesday, September 21, 2004 - 6:43 pm: | 
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I have a galaxy 949 with a k40 truck lip mount. when I am not moving my swr's are fine but when i modulate they swing up to 2.5 and when I am moving they will go higher. I have tried adusting the stinger but they will still not go down. Any suggestions |
Bruce
Senior Member
Username: Bruce
Post Number: 1602
Registered: 9-2003
| | Posted on Tuesday, September 21, 2004 - 6:55 pm: |
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now to see what your swr would be at say 80% modulation you would have to feed in a tone and adjust the swr meter for full scale then read the reflected ( swr )....... there should be little change. |
Allagator
Intermediate Member
Username: Allagator
Post Number: 456
Registered: 9-2002
| | Posted on Tuesday, September 21, 2004 - 7:43 pm: |
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or it could be in the grounding of the lip mount !! making a poor ground with the paint in the way of making a conection !!! most lip mount's wont ground very good try running a extra ground wire to the lip mount to make a better ground !!!!
but its just my to cent !!!!
Allagator |
Bruce
Senior Member
Username: Bruce
Post Number: 1604
Registered: 9-2003
| | Posted on Tuesday, September 21, 2004 - 9:13 pm: |
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COOOOOOuld be gator good thinking! |
Brewdirect
Member
Username: Brewdirect
Post Number: 54
Registered: 7-2004
| | Posted on Tuesday, September 21, 2004 - 11:14 pm: |
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What are your SWR's when not modulating? Are you readjusting the calibration for the higher output when modulating?
If you put out 4 watts and have a 1.2 SWR but then flick on an amp and run 100 watts it's necessary to readjust your calibration for the higher output.
You'll probably only be doing 12 watts at full modulation if that radio has had a tune up, but if you calibrate during modulation it should give you a better idea of what the actual SWR is.
If you can't get it lower, run a piece of ground strap from the bottom inside of the mount to the vehicle frame, or at least to a large body of metal to help in the grounding. |
That ELCO Guy (Unregistered Guest)
Unregistered guest
| | Posted on Wednesday, September 22, 2004 - 7:52 am: |
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@ BR...
Gator and Bruce are right. Hi guys.
There should be little change in SWR readings. Gator may be on to something though--grounding. Try this. scrape off the paint on the underside of the trunk where the screws that secure the mount to the trunk come into contact with the trunk. Make sure that the screws are contacting "Bare Metal" and not just the paint. Check to make sure that the metal is not rusted, greasy or dirty.
ALSO take a piece of braid from a piece of coax long enough to reach from the tunk to the Metalic Body of the vehicle and attach the ends via small self tapping screws to the trunk itself AND the metalic body of the vehicle just in case the trunk lid itself is not making good physical contact with the rest of the vehicle--you are making a bonding strap. You will probably want to do this in an inconspicious place making sure that the securing screws do not poke out the vehicle ;-).
Believe it or not, some amateur operators do this to their vehicle on all the doors, hood, trunk lid, quarter pannels and everything metal that comes in pieces (EVEN the exhaust system pipes) to the chassis of the vehicle. They bond the entire vehicle into one electrical unit. A bit overboard? Some say yes some say no ;) Does it make any difference? Some say yes some say no. I imagine it depends on the vehicle. The only way to find out is to try, ey? ;-)
One last thing to check, go over the install job on the vehicle and compare it to the instructions that came with the antenna just to be sure that the installation was done as the instructions state.
Signed
That ELCO Guy
OOOOH and PS....
Do NOT put the antenna near any computer control box that operates the vehicle. These auto makers of today do not shield their computer boards very well and the RF may make your vehicle operate unsafely--the computer board may go wacko.
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Davesmeg
Junior Member
Username: Davesmeg
Post Number: 18
Registered: 3-2004
| | Posted on Wednesday, September 22, 2004 - 4:08 pm: |
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The SWR is NOT changing when you modulate on AM.
What is changing is the ammount of reflected power. This is what your meter is detecting.
Do as Bruce says and make a continuous tone, a whistle or something, when you check the SWR next time. |
Mdiver
Intermediate Member
Username: Mdiver
Post Number: 177
Registered: 11-2003
| | Posted on Wednesday, September 22, 2004 - 9:44 pm: |
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WHO IS THAT ELCO Guy?
Steve |
Bruce
Senior Member
Username: Bruce
Post Number: 1612
Registered: 9-2003
| | Posted on Wednesday, September 22, 2004 - 10:30 pm: |
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THE SHADOW KNOWS ................... |
Tech808
Moderator
Username: Tech808
Post Number: 3657
Registered: 8-2002
| | Posted on Thursday, September 23, 2004 - 7:54 am: |
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Well I am not the Shadow but I know. 
But the Elco Guy is 100% correct as I have posted many time's before on this topic.
And the Ford Taurus is one of the worst of many vehicles for Trunk Lip Mount Antennas as it has Nylon Bushings in the trunk hinges which prevent grounding to the body of the car.
On Corncob's CEF166 new taurus I suggested he Remove the paint to bare metal where the Trunk Lip Screws tightened to the Trunk and then run a ground wire from the K-40 Trunk Lip Mount screws down thru the trunk to the frame.
Solved the Problem & works great. 
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Karatebutcher
Senior Member
Username: Karatebutcher
Post Number: 1758
Registered: 7-2002
| | Posted on Thursday, September 23, 2004 - 8:47 am: |
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he knows. ya he do |
Ca346
Senior Member
Username: Ca346
Post Number: 1035
Registered: 8-2003
| | Posted on Thursday, September 23, 2004 - 5:09 pm: |
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Well everyone has the right to remain anonymous. Maybe his Ham friends would give him some trouble about CB? You know how we dual hobbiests can be...  I sure appreciate his comments! |
