RFI-Somebody please choke me....

[FatHam]

Dovetailing on Mole's "worst RFI" thread, I've got an RFI issue that I could use some advice on.

My IC-706MkII (barefoot) turns my LCD TV on/off when I'm talking on 10M. It also kicks the fan on, on my central heat/ac on 20/40m. Just the fan, not the furnace or AC unit, so it's messing with the fan relay. The TV's the biggest problem, because when it turns it on or off, it renders the remote useless. the TV has to be unplugged from the wall and re-started for the remote to come back. How convenient <as said in my wife's best "Church Lady" voice>.

Mr. Moleculo, (who's practically a neighbor) looked at my set-up and the first thing that came to mind was my lack of a proper station grounding system. I drilled the floor right under my rigs, installed two full length ground rods and connected them to all of my radio's, tuner, electrical ground, etc... with a 2" X .060 copper strap. Didn't fix it.

Next we looked at the G5RV-jr antenna. It's 35' off the ground at it's center (20' over the roof peak in an inverted "V" installation) with it's ends roughly 6' over the roof peak. I've got a 21' air choke in the coax right at the end of the line where it connects to the ladder line. The suspected culprit here is the ladder line, which is only a couple of feet off the roof at it's feed point. I considered switching to a coax fed antenna to ditch the ladder line, but unfortunately, i'm not finding much along those lines that will work on my city sized lot. The G5RV-jr is only 52' long, has got me 7000 miles on 100W and I'm not unhappy with it other than these two RFI issues.

On to the question...
I'm going to try some chokes on the TV power and fan relay lines, but am not sure where to start, short of ordering everything I can find. Below are links to three different MFJ chokes. I was going to order the MFJ-701, but would like some guidance from some of you RFI Guru's.

MFJ Enterprises Inc.
MFJ Enterprises Inc.
MFJ Enterprises Inc.

Thanks in advance for your time and wisdom!

 

[Moleculo]

Next we looked at the G5RV-jr antenna. It's 35' off the ground at it's center (20' over the roof peak in an inverted "V" installation) with it's ends roughly 6' over the roof peak.

Remember, that ladder line that starts 6' off the roof is part of the antenna and it radiates. That radiation so close to the house is what is causing you trouble. Grounding the equipment in the shack helps with any stray RF radiation caused from equipment in the shack, but it's not going to cure what is coming into the house from the antenna itself.

About the chokes you linked to: The ones you want are made of Ferrite. Either the snap on or the cores may work; the difference is a matter of convenience. You will likely need several of them stacked together with as many turns as you can manage without overlapping to make enough impedance to eliminate the RFI behavior. Also, if I read that last MFJ link, it appears to me that the ferrite in that one is #61 mix. That might work, but wouldn't be my first choice.

Also, it would be helpful if you can determine whether or not the HVAC fan is DC or AC. If it is a DC fan, a simple .01uf or .1uf ceramic disc capacitor or two across the power leads will block the RF.

 

[Robb]

Does the RFI get worse on any particual freq?

 

[FatHam]

About the chokes you linked to: The ones you want are made of Ferrite. Either the snap on or the cores may work; the difference is a matter of convenience. You will likely need several of them stacked together with as many turns as you can manage without overlapping to make enough impedance to eliminate the RFI behavior. Also, if I read that last MFJ link, it appears to me that the ferrite in that one is #61 mix. That might work, but wouldn't be my first choice.

Sounds like a mess. lol Here's the $1,000,000 question if i'm going to have to stack them. Do they need to be as close to the cord's input to the TV as possible, or can they just go anywhere on the line? That could be a deal breaker...

Does the RFI get worse on any particual freq?

No difference, but I'm in a pretty narrow range (28.3 - 28.5) as a newbie. Mole's the only one who's done 20 & 40 on my station, so the fan's not much of an issue until I upgrade.

 

[Moleculo]

Sounds like a mess. lol Here's the $1,000,000 question if i'm going to have to stack them. Do they need to be as close to the cord's input to the TV as possible, or can they just go anywhere on the line? That could be a deal breaker...

As close to the TV as possible.

Oh yeah, I forgot to tell you: Sometimes it can just be the device itself that is the problem. Cheap and inadequate shielding within the electronic device (TV) can also be the culprit, in which case your options are pretty limited.

 

[FatHam]

A

Oh yeah, I forgot to tell you: Sometimes it can just be the device itself that is the problem. Cheap and inadequate shielding within the electronic device (TV) can also be the culprit, in which case your options are pretty limited.

Oh yeah, I forget to thank you for pushing me into HF. The wife is simply thrilled with her new "Home Automation". LMAO

Going to try the ferrite chokes tomorrow. If that doesn't stop it, i'm going to hang a cheap coax fed dipole to see if the ladder line is the source of the grief.

 

[Se7en]

my icom 706mk2g shuts off my 40" TV that is mounted to the roof in the room. my big tube box shuts off the TV and the Verizon fios tv box and wifi which is 60' in another room away...... i gave up on trying to figure it out. figured seeing how most of the stuff, TV wifi etc etc was made in china.... go figure.
also have the 3 standered copper ground rods at the base of my big stick outside.... Good Luck.