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Author Topic: 40 meter RFI in DSL model  (Read 106 times)

K0WA

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40 meter RFI in DSL model
« on: April 30, 2020, 06:21:27 PM »

DSL  modem from ATT shuts down just on 40 meters at power over 500 watts.  Have choke off the phone line with a T240 31 toroid.  I would like to choke one ethernet line going to the shack.  Is there some beads that would work for 7 mhz?  Others,  i can use another toroid.  I am also wondering if it is coming through the wall wart too.  Any recommendations or experiencr?
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W6MK

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Re: 40 meter RFI in DSL model
« Reply #1 on: April 30, 2020, 08:30:26 PM »

Antenna location and feed line setup? Common mode choking in antenna system?
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W9IQ

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Re: 40 meter RFI in DSL model
« Reply #2 on: May 01, 2020, 03:35:08 AM »

Type 31 material is quite good for a 40 meter choke. You can also use type 77 or 75 with nearly equal effectiveness on 40 meters. If you need suppression below 40 meters, then the type 77 or 75 will generally be superior.

If you suspect the wall wart, simply put a choke on its output cord as well. There is no downside to trying it.

As always, if you can put a few turns of the wire on the toroid or large bead, you will generally get a more effective choke.

Make certain you have a good common mode choke on your antenna coax cable as well. It is always better to choke things off at the source.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

W1VT

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Re: 40 meter RFI in DSL model
« Reply #3 on: May 01, 2020, 11:15:22 AM »

If the wires are thin enough, I wrap them all through the same toroid.
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