Light dimmer affected by 20M FT8 transmissions

[KE8WHP]

First post, hopefully I chose the right category.

Am doing FT8 and using an Alpha HOA to load the gutter for my antenna. Have made some good DX QSOs and have a near 1:1 SWR after tuning. Was getting some parisitic vibrations in parts of the house, lots of aluminum trim coil outside. Now I have a donut ferrite with six turns of RG-8X through it and a MFJ-915 RF line isolator on the coax from the radio that fixed things vibrating. Something new then popped up. Have a light dimmer in the dining room going whacko when transmitting. Have the same dimmer in the kitchen with no problems. The feed to the kitchen dimmer is via MC and the feed to the dining room light is romex that is roughly parallel for a stretch and close to the gutter being used for an antenna. I put clip on ferrites near the load center on the romex. Only running 50 watts or less, no linear amp involved.

This dimmer is not a cheapo chopper type. Its a Lutran Sunnata touch dimmer, you use it like a touch screen on the bar on it. Things are fine when the transmitter is off.

Can anyone offer a suggestion on what else I can do to fix this please? For now I am not operating HF at night, yet that is when I have the most time to sit in the shack.

Thanks for any ideas you can offer to me, I would love to get my wife happy again by fixing this.

 

[tvengr]

I would be very concerned about someone touching the downspouts while you are transmitting. RF can cause severe injuries. What precautions are you taking to keep people and animals away from the downspouts?

 

[prcguy]

Is this a wall mounted dimmer in an electrical box? Ceiling lights or plugged into a socket? I would try a ferrite choke at the input and output of the dimmer to see where it’s most vulnerable to RF. You can wrap 9 turns of appropriate size wire for the breaker like three 14ga or 12ga around an FT240-31 ferrite torrid and temporarily connect it to the dimmer hanging out of the wall. I would use three wires to include the safety ground as RF can travel from your coax to the radio chassis, power supply chassis and power supply earth ground wire Into the AC socket.

I can almost guarantee that will snuff out the problem and once you determine if the input or output side of the dimmer is the fix you can hopefully stash the torroid filter inside the wall. The choke would look something like this but more tightly wound with smaller gauge wire.



You can leave long leads on the toroid to reach from inside the wall to the dimmer and use wire nuts or terminal blocks like below.