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Author Topic: Getting into computer and speaker  (Read 5168 times)
KD0LAV
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Posts: 78




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« on: October 06, 2013, 06:01:23 AM »

Have an OCF Windom, newly installed that is only about 5 ft off the roof of the house.  When transmitting on 40M the computer monitor will shut off or at least go blank and I come thru the computers speaker.  Am running a Kenwood 590 with no power.  When using the hexbeam I don't have this problem.  Have checked 20M on the Windom and the same thing happens.

Am a relatively new ham and RFI is not something I am familiar with before the Windom.
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K5LXP
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« Reply #1 on: October 06, 2013, 08:15:11 AM »

This sounds like basic fundamental overload.  Hard to tell from the description if the incident energy is from the proximity of the antenna, or your feedline.  OCF's by their nature will have feedline radiation, somewhat less with a current balun.

First thing I would do is the standard interference level assessment.  Find out what bands, and what power levels cause the problem.  Then you can make a change, such as adding a choke balun, reorient the antenna, EMI mitigation on the affected equipment, etc.  Re-run the test to see if the interference still happens, and at what levels.  If it takes more power than before to cause the problem, you're on the right track.  If it's the same you know you need to try something different.

This is an iterative process and there's usually no magic bullet solution.  The solution may be a combination of changes to the antenna and the affected equipment.  Keep after it and you can usually lick it.

Mark K5LXP
Albuquerque, NM
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W7VO
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« Reply #2 on: October 15, 2013, 04:59:46 PM »

Am running a Kenwood 590 with no power. 

That is quite a feat to have RFI problems with no power!  Grin

K5LXP is right. Time to start wrapping leads up with ferrite beads and donuts. Make sure you have a 1:1 balun on the antenna to keep RF off the feedline. I had terrible problems here on 80M with my computer mouse freezing up and cured it by wrapping the USB mouse cable several times through a ferrite donut right at the computer connection.

Good luck!

Mike, W7VO
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WX7G
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« Reply #3 on: October 15, 2013, 05:25:59 PM »

DX Engineering stocks snap-on ferrite core kits.
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KD0LAV
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Posts: 78




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« Reply #4 on: October 15, 2013, 05:46:24 PM »

I know this is going to show my ignorance having never been around baluns before.  I assumes the cylinder at the antenna feedpoint was a balun.  Am I wrong in assuming that?
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K9IUQ
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« Reply #5 on: October 17, 2013, 05:15:18 AM »

Am a relatively new ham and RFI is not something I am familiar with before the Windom.

Windoms are well known for RFI problems in the shack. There are better all around antennas to use.

DX Engineering stocks snap-on ferrite core kits.

Yep, DXE has some really good ferrite core kits. They work. I had much RFI problems with a Flexradio 5K a couple of years ago. I put ferrites on everything in the shack including my German Shepherds tail. It worked, no more RFI and it cost me $100 worth of ferrites but the GS Dog did not like it much.

I got rid of the Flexradio and put all the ferrites on the shelf. No more RFI problems and my GSD is much happier.

Stan
« Last Edit: October 17, 2013, 05:17:45 AM by K9IUQ » Logged
KD0LAV
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« Reply #6 on: October 18, 2013, 05:50:51 PM »

Stan,  What would you recommend?  I have limited space and power lines across the back of the yard.
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N1UK
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« Reply #7 on: October 30, 2013, 10:09:54 AM »

What about a dipole or fan dipole if you want to go resonant. Also try and get it higher off your roof ie further away from the shack


Mark N1UK
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