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Author Topic: 15m on amplifier shuts my PC off haha - Suggestions?  (Read 4039 times)
KK4YDR
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Posts: 673




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« on: February 21, 2016, 04:46:50 PM »

So when ever I use more than around 200 watts, I can do legal limit, on 21mhz (15m) my PC will shutdown on me. Actually it will just crash to a black screen. All other frequencies are fine.

This happens on my 80m loop. I get NO stray rf in the shack, I have done everything to properly eliminate stray RF. I feed my antennas (160m loop and 80m loop) with ladder line to a balanced line tuner, Palstar BT1500A.

I know that there are subsystems in PCs that function on different frequencies for instance. 48mhz is most USB controllers.

With ferrite chokes I have eliminated much of the RF coming from my antenna, penetrating my house, and making my speakers talk to me, amongst other things. However I do not know what fix may exist for a PC to shield it from RF. My antenna basically surrounds my lot, all 600 foot of it and my house is in the middle. So when I do a 1500 watt keydown I am right in the loops donut of radiation.

Any suggestions or do I just throw the towel in and live with working 15 meters barefoot?
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W1VT
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« Reply #1 on: February 21, 2016, 04:57:24 PM »

Do you have a 15 turn RF choke on every single wire going to the PC?  Every wire could be a culprit, so you really want a choke on every wire.

Zack W1VT
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KK4YDR
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« Reply #2 on: February 21, 2016, 05:29:39 PM »

I will choke every wire going into the PC then. They are probably just acting like antennae.

Not sure what you mean about 15 turn RF choke. If you imply I can get 15 turns per choke per wire that is NOT going to happen. Some of these cables are only 3 feet long and are extended almost fully.
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W1VT
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« Reply #3 on: February 21, 2016, 05:49:18 PM »

The impedance of a choke varies with the square of the turns ratio.  A few turns may not be effective at HF.

http://www.karinya.net/g3txq/chokes/
Here is a graph of some optimized chokes

Zack W1VT
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K3DCW
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« Reply #4 on: February 21, 2016, 06:56:33 PM »

So when ever I use more than around 200 watts, I can do legal limit, on 21mhz (15m) my PC will shutdown on me. Actually it will just crash to a black screen. All other frequencies are fine.

Does "crash to a black screen" mean that the actual computer shuts off, or just your monitor? 

I had problems in the past (even at 100w) with monitors that used touch controls (Samsung seemed to be the worse) on the front. Replaced them at the time with LG monitors using actual buttons and the problems went away.
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Hamming it up on OS X!
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KK4YDR
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Posts: 673




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« Reply #5 on: February 22, 2016, 01:08:23 AM »

The impedance of a choke varies with the square of the turns ratio.  A few turns may not be effective at HF.

http://www.karinya.net/g3txq/chokes/
Here is a graph of some optimized chokes

Zack W1VT

I use 8 turns through 31 mix split beads mobile. But there isn't enough physical cabling of my keyboard mouse, audio, video, etc.. that can make 15 successful turns through a bead. I find that about 5 turns on average in my house tends to work decent for some stuff. I will stuff as many turns as I can and see what happens.

Does "crash to a black screen" mean that the actual computer shuts off, or just your monitor? 

Yeah it's not my monitor. When I restart my PC I get specific error codes that let me know what happened. I am going to split bead all the input cables and see what happens. Past that point I guess I will just have to shut my PC off and paper log my high power 15 meter QSOs whenever I work that band.
« Last Edit: February 22, 2016, 01:11:05 AM by KK4YDR » Logged
K8AC
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Posts: 1897




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« Reply #6 on: February 22, 2016, 05:58:23 AM »

After properly choking all lines going into the PC, look carefully at your PC case.  A good one will have conductive seals on all removable panels.  There will be metal to metal contact between the removable panel and the case.  If the case is all plastic, there's not much you can do except to replace it with a good all-metal case. 
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KK4YDR
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« Reply #7 on: February 22, 2016, 10:44:09 AM »

After properly choking all lines going into the PC, look carefully at your PC case.  A good one will have conductive seals on all removable panels.  There will be metal to metal contact between the removable panel and the case.  If the case is all plastic, there's not much you can do except to replace it with a good all-metal case. 

Ahh yeah good point. Kind of like a faraday(spell?) cage.
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