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03-10-2012, 09:41 AM
 
I would try tuning your antenna some more and see if you can bring that SWR on channel 40 down. The mount does need to be grounded really well, so as long as the bolts are touching bare metal you are OK. I actually have a jumper wire running to my mount to ensure a good ground (overkill yes).
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03-11-2012, 05:14 AM
 
Quote:
Originally Posted by mr. SlippyFist View Post
I have the new antenna mounted, wires ran, and a new CB wired up. Im hearin truckers on 95, 695, and some down in the city (about 15- 20miles away). I am however getting some pretty bad interference on all channels. Im thinking its because I (stupidly) ran the coax and power wires together. As my buddy was leaving i was just testing how the voice quality was as he drove away and when he got about 200 yds away he said it got staticy(?) and I cut out. Now, i didnt sand the paint off my bumper where its mounted so do you think the antenna ground isnt strong enough to transmit as strong as it should?

I used the built in SWR meter (i guess works) and went throught the channels 1-20-40 "by the book" and after tuning got these readings.

1 - 1.2

20 - 1.3

40 - 1.8 (very close to 2)

Im thinking (after i get my paycheck) of just getting a dedicated SWR meter like Ohio said to make sure the readings are legit
Did you verify the mount to tub resistance is low? What resistance did you get?
Having good metal to metal contact is important for a antenna ground. This will help get lower SWR overall. When checking your radio with another vehicle it is best to start 100 ft or better away. If you are too close you may be swamping the other radio's input. However it you are really getting our only 200 ft there is an issue. Be sure your friends radio does not have squelch up and RF gain down because you were next to eachother to start. Be sure your SWR is below 2. Yes 1:1 is best but for one mile this will not matter. Just being below 2 is important. The RF gain and squelch only effect your radio's receive. If you have Dyna gain this is your Mic gain and could give choppy transmitting if turned up to far, but will not limit distance.

Noise receiving or transmitting - First some background noise is normal. The sun's activity is at a high and the other day sunspots and solar flairs were at a high and will be for the next year. There are other sources for noise as well.


The Noise you are receiving could be either noise coming thought the power wires or it could be transmitted noise. The source could be your jeeps electrical or the surrounding area.
First determine if it is transmitted or coming in through the power wires. RF gain at max and squelch at min. Remove your antenna from the back of the radio. Without transmitting turn the radio on and start your jeep. Any noise??
Next reconnect the antenna and engine off but radio on (assuming you wired this directly to the battery) any noise? Key in the on position. Noise?? Engine On Noise?
There may be things in your surrounding area so doing this in an open area may help. For example high tension wires or certain businesses transmit noise several hounded yards from their businesses. I drive past 2 every day. and When under high tension wires there is a buzz.

Once you find the source and fix it you could change your RF gain and squelch to normal levels. But I have my squelch less than 1/4 up and RF gain at max. I only turn RF gain down when someone is too close or transmitting too much power.



An external meter is important but is not necessary too and should not be left in the system. Leaving it in changes the impedance the radio sees.


Hope this helps.
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Last edited by JPNinPA; 03-11-2012 at 05:33 AM..
 
 
 
 
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03-11-2012, 12:00 PM
 
I don't have a multimeter on hand, but could get ahold of one tomorrow. As for the noise/interference coming through, I toyed around a little and turned on the "NB/ANL" switch and 80% of it has gone away. The RF gain is all the way up, squelch is t about 25% and my mic gain is at around 60%. Im getting PLENTY of chatter and some real comedians on ch22. Still have not been able to get through to them so im guessing the radio is not transmitting too well.


I've gotten a dedicated SWR meter and gave me some readings that were different,

1 - 1.3

20 - 1.9

40 - 1.5


My antenna is only 3ft now, mounted at the same location as the 4 ft one. Do you thing its the height of the antenna and how close it is the the front of the jeep that's giving it a high SWR? (still have my receipts to return them no problemo)
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03-11-2012, 12:30 PM
 
Are you tuning this in an open area with doors and hood closed?
If you look at the antenna you could see the wire spiraling around the fiberglass rod. There is an area that is tightly wound. As long as this is above the hood and not within a few inches it shouldn't be an issue. Anyway this will effect the SWR reading and change the way the antenna radiates. You will have good forward transmission but poor to the rear.

Your readings are the reverse of what is expected. It should be lowest in on 20 and higher at 1 and 40. Tune for a low at 20. You could run an additional ground as OhioYJ mentioned ( I have one too) to see if your mount needs an improved contact. Being this is on the bumper I would not leave the additional ground as it will likely get pulled off when wheeling or fail due to exposure.


PS You will likely hear farther signals than you can reach. Some of those guys may be running illegal outputs or be HAM type operators on lower frequencies.
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Last edited by JPNinPA; 03-11-2012 at 09:19 PM..
 
 
 
 
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03-15-2012, 10:06 PM
 
Did you ever get this sorted out?
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