RFI issues causing USB devices to uninstall on PC

5.11 Tactical

Maybe someone can answer this for me.

I am currently running a president grant 2 via a horizontal dipole in the attic for a little bit of Dx'ing.

I am running standard power on USB of 11 to 12Watts.

The issue I have the rig is beside my PC and when I key up on SSB and transmit it causes some wired USB accessories to uninstall and reinstall on the machine about 5 feet away, like the keyboard and a cable connecting my iPad.

I have ferrite cores on all cables on the CB including the Coax and my SWR is flat on 10/11/12 metres.

Is there any filters I can use to stop the RFI interfering with my PC ( I have moved the rig to the other room but it continues to occur) and I have a second Grant 2 and the same issues and both are brand new.

Any ideas what I need ?

Fuzzy Clam

Its the proximity of the antenna, not the cb, that's the problem.
Ferrites on the cb cables are unlikely to help, although one on the coax can help sometimes.
Its the cables on the PC and associated devices that need rfi suppression.
I've had a lot of success wrapping 8 to 10 turns on a type 43 ferrite ring, but that was eliminate lower frequency, you wouldn't need that many turns.

micko45

Perhaps the feed line is radiating all the way back to the radio, do you have a balun/choke on the dipole? Did you buy it or home-brew it?

I have a similar issue. I built a new antenna recently for 80m/40m, and my usb keyboard removes its self from the pc when i go over 15w. So I plan to get 20' of RG58 and wrap it around a 4 or 6" pipe so to create a rf choke.

http://www.hamuniverse.com/balun.html

Currently I'm waiting for rg58 to arrive.

PauloMN

I agree on the balun point above. If you don't have one, get one.

Also indoor TX antennas are always asking for trouble imo. Even up in the attic, you are probably filling the whole mains circuit in your house with RF which won't help. If there's anyway to get the antenna outside, you should do that.

5.11 Tactical

Thanks for the info lads.

I put ferrite clamps on the PC on all the cables (Overkill) but it has stopped.

I am running a homebrew 1/2 horizontal dipole in the attic as local restrictions about antennas and dishes prevent me from putting them up.

So a compromise antenna, but I am looking at other internal options.

Currently studying for my amateur radio exam for the new year and makng different antennas.

In regards to the balun, anyone have any suggestions about a commerically available one, I know I can make one but I am a beginner so will try down the line.

Again all thanks for the info and 73's

5.11 Tactical

micko45 wrote: »

Perhaps the feed line is radiating all the way back to the radio, do you have a balun/choke on the dipole? Did you buy it or home-brew it?

I have a similar issue. I built a new antenna recently for 80m/40m, and my usb keyboard removes its self from the pc when i go over 15w. So I plan to get 20' of RG58 and wrap it around a 4 or 6" pipe so to create a rf choke.

http://www.hamuniverse.com/balun.html

Currently I'm waiting for rg58 to arrive.

Thats exactly was happening to me (put the ferrite clamp on the cable and it was gone...I used a 5mm clamp)

thelordgod

An rf choke made of 20ft of coax wrapped around a bit of sewer pipe of a flower pit will do the trick as micko has said. All you need to do is have an extra 20ft on the feedline and wind it into the plastic former. No connectors are needed. Yes there is a little loss but I doubt you would notice it.

humaxf1

As others have said, I wouldn't purchase a choke balun (yea, I know - more of an Un-Un) or LINE ISOLATOR as they are sometimes known as <bit of snake oil advertising there>

They are a complete rip-off and you can save a few quid from making your own. Also, ensure the aerial is as resonant as you can get it - i.e, lowest SWR for the frequency +/- a few khz where you operate the most.

5.11 Tactical

Thanks for the all the info guys.

Made myself an ugly balun and all cables also now have feritte clamps fitted.