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RFI unresolved

Feb 6th 2018, 22:46

smecca

Joined: Oct 27th 2014, 03:17
Total Topics: 0
Total Posts: 0
RFI in the shack, especially on the AC side. 40m and 80m are the worst. The upper bands are on a delta loop at 45'. 40m is a double bazooka at 30'. 80m is an inverted L at 33'. Over 30 radials, 5 ground rods spaced at 8' Cadwelded with #4 copper. Ferrite beads on all RF leads and the AC power cords. UnNun baluns and everything bonded in the shack. I even have a small Farady cage around the radio and amp. The AFCI all trip at key up. Not sure what else to try. The antennas are all right above the radio, tuner, and amp. The vertical mast is literally within 7' of the equipment. One ham said that I would never get rid of the RFI until I move the antennas away from the shack. The vertical mast is within 12' of the meter base to the house. What can be done???

BTW...... I have replaced all of my Eaton breakers. I even had them replaced in my neighbors.

This condition has worsened since I installed an amp. Not tripping my neighbors breakers. Is it possible this is an issue with RFI going back on the AC cord from the Amp (ACOM 1010)? I have 5 ferrite beads on the power cord.

I also question if my breaker panel has a good ground.

Another ham has told me that my antennas are just too close to the shack and the house.
Feb 15th 2018, 14:59

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Ferrite beads are typically ineffective at HF until you reach the equivalent of 50 beads. The most practical way of doing this is to wrap cords through FT-240-43 toroids--I find that with thin computer cables I can wrap two or three cords through one toroid. The inductance varies as the square of the turns--10 to 15 turns is the equivalent of slipping 100 to 225 beads over a wire.

One approach is simplify, and see what you can do to get a minimal station going. Then add cables until you have issues, and then fix that. This may reduce the number of variables and make the situation more manageable.

It certainly helps to get the antennas away from the shack, if that is possible. Many hams have found that it is easier to move the antenna than to fix the numerous devices that generate noise. The huge improvement in reception often offsets the small coax cable loss on transmit if your antennas have a reasonable SWR.

Zak Lau W1VT
ARRL Senior Lab Engineer
Feb 20th 2018, 09:52

smecca

Joined: Oct 27th 2014, 03:17
Total Topics: 0
Total Posts: 0
Thank you Zak. I do have some toroids but have not used them. Have you ever used the toroids on the AC power cables?

BUT...... Here is an update. I have the issue 95% or more resolved. I had to isolate the ground radials to just the shielded end of the Inverted L. In other words..... the ground radials were tied to the mast holding all of the antennas. I pulled them from the mast ground post and tied them directly to the grounded end of the antenna. I can run 500W on 80m now and there is not a single issue. This also took the ground radials off of the same ground as the equipment. There is now just a small amount of common mode on my 40m but I suspect the ugly balun will nail that.
Feb 20th 2018, 11:05

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I typically use toroids on wall warts. So far, I've not found it necessary to filter the big power cables--but you can buy special filters for them. Sometimes, careful inspection of something like a computer power supply will reveal the use of a proper filtering circuit.

http://www.morganmfg.us/radio-products/ac-line-filters-protectors/

Zak Lau W1VT
ARRL Senior Lab Engineer

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