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Author Topic: RF kills USB connection  (Read 1711 times)
N4EDI
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Posts: 15




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« on: September 19, 2014, 01:36:31 PM »

I have a new Dell XPS 8700 with Windows 8.1 and use Ham Radio Deluxe connected to my radio by USB cable. Every time I key up on 80 to 17 meters it kills my USB connection. I am using a Buckmaster 7 band antenna which is hung about 30 feet from my shack. I have put multiple ferrite beads on every cable attached to this computer but it has not helped. I tried turning the power down as low as it will go on my radio and it still killed the USB connection.
I hooked up my old Dell XPS 400 with Windows XP and there are no problems. It is sitting close to the new computer. Does anyone have any ideas how to keep RF out of my new computer?
Thanks
Ed
N4EDI
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KD6NIG
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Posts: 34




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« Reply #1 on: September 19, 2014, 01:55:14 PM »

I had this issue when I bought a USB connector that had multiple ports on it (2 instead of 1).

No matter what I did it would disconnect the moment I used the radio.  One was connected to the transmitting rig and the other was connected to my packet station.

I tried beads, etc, even relocating the USB to the other side of the computer, extending it out, and keeping them a few feet away from the radio.

I finally returned the dual to Amazon and instead ordered 2 single ported ones.

I hooked them up and it has worked fine without any issues.

The only noticeable difference between the two besides the fact one was a single usb with two ports is that the USB cable from the converter to the computer was a bit thicker.

I'd have to look at them to tell you the brand though, they are both the same.
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ND6P
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Posts: 93




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« Reply #2 on: September 19, 2014, 09:17:51 PM »

You might try to disconnect all cables from the computer except the one you use to connect to the radio and see if the problem goes away.  If it does, then add them back one at a time to see which one is carrying the RF.  And try removing all cables from the radio except for power, antenna, and USB to see if that helps as well.

Another trick I've tried is using a spare ac cord with the ground lug removed to power the computer to see if that helps.  If not, then put the original one back in.

And a choke on your antenna feedline where it enters the shack is important as well.

Jim/ND6P
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WX7G
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Posts: 6056




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« Reply #3 on: September 20, 2014, 08:14:09 AM »

Does the problem occur on 10 meters? Have you tried this with a dummy load? The reason I ask is to make sure the problem is caused by RF rather than some USB communication sent by the radio that corrupts the program.
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N4EDI
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Posts: 15




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« Reply #4 on: September 20, 2014, 11:48:09 AM »

It does not happen on 10 meters only 17 through 80. 40 meters seems to have the worst effect. When I key up on 40 I get 4 or 5 icons in the task bar saying trying to connect USB device or something like that the the connection is lost. I have not tried a dummy load yet. I have tried disconnecting all the cables that are not needed for my radio connection and it did not help. I have not tried the spare ac cord with the ground lug removed. I need to give that a try.
Thanks
Ed
N4EDI
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WX7G
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« Reply #5 on: September 20, 2014, 12:19:41 PM »

OK, that it does not occur on 10 meters confirms that it's an RF issue. A dummy load test is not needed.

Cutting the PC ground pin is an interesting experiment. But as the PC chassis is connected to the AC line and neutral conductors though EMI Y-capacitors the chassis is virtually shorted to the AC line conductors which are tightly coupled to the AC ground wiring in the wall.

You tried ferrite cores but are they the right kind? If they are large enough the USB cable can be looped through five or six times. This makes one core as effective as 25 or 36 cores. Fixing the problem with the other PC cables disconnected is a good idea.

Another experiment is to connect a 1/4 wavelength radial to the transceiver ground post. For 17 meters the length is 13 feet. This can reduce the RF potential on the radio chassis and result in less RF current between it and the PC.

 

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N4EDI
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Posts: 15




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« Reply #6 on: September 20, 2014, 03:28:48 PM »

The ferrites that I used are the snap on ones from Radio Shack. If these are not right what should I be using and where can I get them?
The problem computer ac is connected to a UPS battery backup. Could this be the problem?
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WX7G
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Posts: 6056




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« Reply #7 on: September 20, 2014, 08:05:41 PM »

I've used the Radio Shack ferrites and they worked with multiple turns of cable through them. The snap on ferrites from DX Engineering are worth a try.

To test whether the UPS is a problem you can plug the PC directly into the wall outlet.
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