| Author |
Message |
    
Pintail617
New member
Username: Pintail617
Post Number: 1
Registered: 2-2004
| | Posted on Saturday, April 17, 2004 - 11:43 am: | 
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My dad has 2970 in a 2000 nissan maximum, with cobra hg-a2000 magmount antenna. It has perfet swr, and works very well, except when the electric cooling fans come on. Then the radio makes an awful whine. He has tried the following products with no luck.
.5 uf 40 amp 50 volt feed thru noise filter
pyramid #ns50 heavy duty noise suppressor 35 amp.
What are some other products or options that he can use to fix this? I hope that I given enough information,if not let me know.
Thanks Pintail 617 |
Dx431
Advanced Member
Username: Dx431
Post Number: 852
Registered: 2-2002
| | Posted on Saturday, April 17, 2004 - 12:41 pm: |
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Did he connect this noise suppressor on the leads on the radio or the leads to the fan?
The noise filter should be installed on the wire leads to the fan. Always go to the source of the noise to solve the problem.
Hope this helps..... |
Pintail617
New member
Username: Pintail617
Post Number: 2
Registered: 2-2004
| | Posted on Saturday, April 17, 2004 - 3:37 pm: |
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He tried them both to leads of the fan. He has two fans on the car so he used two of them. Let me know if you have any other suggestions. |
Kc0gxz
Advanced Member
Username: Kc0gxz
Post Number: 750
Registered: 3-2003
| | Posted on Sunday, April 18, 2004 - 4:00 am: |
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Pintail617
Unhook the coax from the back of the radio and see if the fan noise goes away. If it does, that obviously means that the antenna is picking up the noise.
If it doesn't go away, then the noise is coming in through the power leads. Personally I can't think of anything else other than the good advice that Dx431 suggested. Other than maybe running the power leads of the radio directly to the battery if you haven't already.
If the noise goes away when you unhook the antenna, the problem is with the antenna and its coax. If this is the case, how about trying a real grounded antenna system. Your whole radio system SHOULD be grounded and the way you explained your system, you do NOT have a true ground at the antenna.
If you are stuck with using a magnet mounted antenna, then perhaps you should try a different brand. There are "FAR" better antennas out there that can be used with a good mag-mount. We'll talk about that later if the need arises.
But first you have to determine if the noise is coming in through the power leads or if the antenna itself is picking up the noise. Let us know what you find. Hopefully we'll get this thing figured out.
Jeff, kc0gxz. |
Pintail617
New member
Username: Pintail617
Post Number: 3
Registered: 2-2004
| | Posted on Sunday, April 18, 2004 - 3:53 pm: |
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It only happens when you unplug the antenna. He even tried the antenna on the roof, and also laid all the coax outside the car to make sure it was laying next to any other wires in the car. Can you ground a magmount??? Keep the good ideas comin. Thanks for all the help. |
Cuddlebear
Intermediate Member
Username: Cuddlebear
Post Number: 124
Registered: 3-2002
| | Posted on Sunday, April 18, 2004 - 5:02 pm: |
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I have always been told that when a mag mount is put on the metal of the car, it is grounded to the chassis already. But never having used one, I'm not entirely sure. |
Kc0gxz
Advanced Member
Username: Kc0gxz
Post Number: 758
Registered: 3-2003
| | Posted on Tuesday, April 20, 2004 - 2:11 am: |
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Pintail617
What do you mean when you said "It only happens when you unplug the antenna".
I'll try this again---
1- What happens when you unplug the antenna? Does the fan noise go away or does it "not" go away???
2- "How" and "Where" are the Noise Filters (that Dx431 suggested) installed on the fans?
3- Did your Cobra antenna come as a complete unit including the magnet or do you have the kind where you had to buy the magnet separately?
4- I think I may have asked this before but, where are the power leads of the 2970 connected to? Hopefully they are connected DIRECTLY to the battery.
5- Do you have the ANL and NB turned on?
------------------------------------
Cuddlebear--The only way you can "ground" a magnet is to pull the plastic off the bottom of it and then strip the paint off the roof where the magnet will be sitting.
Most, but not all, mag mounts that come as a antenna-coil-magnet combination are capacitance grounded. In a case such as that, there is no true ground present. Personally, I wouldn't put one of those on my grandaughters' little red wagon. I prefer a complete grounded antenna/radio system.
Jeff, kc0gxz. |
Pintail617
New member
Username: Pintail617
Post Number: 4
Registered: 2-2004
| | Posted on Tuesday, April 20, 2004 - 4:50 pm: |
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kc0gxz Here you go to your questions:
1. It goes away when antenna is unplugged.
2. Filters on inline on the wires that connect to the fan, and they are closer to the fan than the battery.
3. It is a complete unit like a Wilson 1000 magmount.
4. Directly to the battery.
5. Yes, ANL and NB are turned on.
Hope this gives you enough information. Thanks for the help.
Pintail617, Ronnie |
Cuddlebear
Intermediate Member
Username: Cuddlebear
Post Number: 128
Registered: 3-2002
| | Posted on Tuesday, April 20, 2004 - 6:20 pm: |
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KcO,
Thanks for the info. I have no personal experience with these mag mounts, so that will help me answer these questions better for people in the future.
 |
Kc0gxz
Advanced Member
Username: Kc0gxz
Post Number: 767
Registered: 3-2003
| | Posted on Tuesday, April 20, 2004 - 9:40 pm: |
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Pintail617
OK. Now we're getting somewhere.
Leaving the coax still screwed into the back of the radio, remove the whip from the coil and leave the mag/coil combination mounted on the car.
Now here is my question---with the whip removed, do you still have fan noise?
Jeff, kc0gxz. |
Pintail617
New member
Username: Pintail617
Post Number: 5
Registered: 2-2004
| | Posted on Wednesday, April 21, 2004 - 12:07 pm: |
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Yes. It does make the fan noise. What is next????? |
Kc0gxz
Advanced Member
Username: Kc0gxz
Post Number: 771
Registered: 3-2003
| | Posted on Friday, April 23, 2004 - 5:06 am: |
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Pintail617
That tells me that the coax on your Cobra antenna is bottom of the line stuff.
If you are limited to only running a magnetic type of antenna, then go with a quality brandname such as Wilson. You don't have to buy their most expensive. The Wilson 1000 is one of their best and also one of their least expensive.
OR, you can piece one together yourself. One of the big 5 to 6 inch flat mags are very good and can handle up to 6 feet of antenna. They're relatively cheap. I'm not too crazy about the 17 feet of coax that comes with some of them but it can always be changed to a much better grade. This is the problem that you are experiencing now--lousy coax.
Just because that antenna says "Cobra" on it, it doesn't mean that it's going to be a good one. Someone is just capitalizing on the Cobra name. Cobra DOES NOT make antennas.
Here's something else you may want to think about. Even if you go with a far better antenna and mag-mount combination, you may still experience some fan noise. There is no guarentee that it will go away. A good grade of coax will indeed help in your situation, but it may not eliminate it entirely. That's sometimes when you don't have a comepletely grounded system.
If you are still getting the fan noise with the whip out of the coil, that should tell you something is very wrong with your coax. There is bottom-of-the-line coax attached to that antennas' coil. I suggest you start experimenting with other antennas. Either that or take the car to a dealership and have them fix the problem with the fan.
There's one more thing that I'm curious about. If you put the cars' stereo on a distant A/M station, do you hear the fan noise in that too?
Possibly someone else on the forum can give you some suggestions also. The best suggestion I can come up with is, since you have a good grounded radio, why not run a good grounded antenna system?
As it is now, "YOU DO NOT HAVE A GROUNDED ANTENNA SYSTEM". Only your radio is grounded! And the antenna is the heart of a good communications system.
Jeff, kc0gxz. |
Pintail617
New member
Username: Pintail617
Post Number: 6
Registered: 2-2004
| | Posted on Saturday, April 24, 2004 - 10:26 am: |
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No fan whine on the fm/am radio. I will let him know about some of these options. I told him myself to go with the Wilson, but he is stubborn, I guess that is where I get it from. Thanks for all the advise. I will keep you updated with any changes. Thanks. |
Therealporkchop
Intermediate Member
Username: Therealporkchop
Post Number: 188
Registered: 11-2002
| | Posted on Sunday, April 24, 2005 - 1:58 am: |
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This is long past, but I was reading through the older post and thought I'd put my two cents in.
First you can ground a mag mount. I was told to use no longer than 9ft of ground wire. Tried it on my dumptruck which has fiberglass doors and it helped, swr and receive.
Second I had a whine coming from my alternator. I installed a filter at my radio. I hooked it to the power wire of the radio. Problem solved.
If you are getting noise from fans or alternator try getting a few ferrite cores. Unhook the positive lead from the fan, and wrap a few turns through the core. If this doesn't help, you need to make a shield for the fans/alternator to try to stop the RFI that it's causing and your antenna is picking up.
I've had the same problems and this is how I fixed mine. Hope this helps someone else, cause I am sure Pintail has cured his problem long ago. |
Al_lafon
Junior Member
Username: Al_lafon
Post Number: 28
Registered: 3-2005
| | Posted on Wednesday, May 25, 2005 - 8:38 pm: |
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Hello if i were you look into new fans if the fans
are like the ones found in computers they are very
low noise type may work in place of the stock ones. Are they two wire or three wire computer
fans have a tach wire you may not need. it can be cut out if you find one same size as yours also
look at the info on the package as you can find
some put out more air or lower noise. |
