[RFI] RFI/EMI MAJOR Problems
k2dp at charter.net
Thu Nov 30 00:06:27 EST 2006
I have a couple of suggestions for you.
1) Get the antenna off of the roof and out into the backyard away from the
house. You are essentially radiating back down into your house and every
wire in your attic is acting like an antenna. The further away from the
house you mount your antenna, the better off you will be.
2) Your choice of toroid material is not optimally suited for attenuation of
HF signals. According to Amidon's data sheets, #43 material has optimum
frequency attenuation between 40 mhz and 400 mhz. In general, that is above
the frequency range you are attacking. I have had good success with #77
material, which has maximum attenuation from 0.5mhz thru 50 mhz.
3) Are you using clamp on toroids or donuts in all of your applications?????
Using donuts allows you to get 10-12 wraps of cable around the ferrite
material and places a significant amount of cable "surface area" in contact
with the ferrite when compared to the use of "clamp on" ferrites. In other
words, winding a cable on a 2.5" OD (outer diameter) donut uses about 8-10
inches of cable at a minimum. In order to achieve the same amount of
supression in a cable using clamp on ferrites, you would need to clamp on
the equivalent of 8-10 inches of ferrites .
4) Get everything clean without using the linear amplifier.
5) Remember that when trying to filter various devices, such as cordless
phones, you need to filter the "wall wart" type power supply as well as the
telephone line. Place the toroid as close to the power supply connector plug
where it enters the charging base of the telephone.
6) Refer to the ARRL RFI Handbook for reference..it's very complete.
Good luck and hope this gets you started in the right direction.
St. Louis, MO
----- Original Message -----
From: "Bob Gates" <regates at hughes.net>
To: <rfi at contesting.com>
Sent: Wednesday, November 29, 2006 10:17 PM
Subject: [RFI] RFI/EMI MAJOR Problems
> Hi All,
> I wish all I had to deal with were little noises in my receiver. All of
> my little noises are in my head. I apologize if the problems I'm about to
> describe are not best suited to this forum, but I can't find one that
> seems better suited. If there is, you certainly won't hurt my feelings if
> you tell me to look elsewhere.
> My problems start when I turn on the linear, at anything over about 500w
> output. At that point I generate major TVI, to the tune of completely
> blanking out the screen. All cordless phones receive my signal S9, before
> disconnecting the phone altogether. I start tripping GFCIs in some parts
> of the house, and can even lock up my PC on one band, after listening to
> audio/cw coming through the PC speakers. I have mix 43 toroids, in
> various combinations, all through the house, to the tune of 48 of them.
> I have 8 of them forming a common mode choke at three points on my single
> antenna feed line. I have another choke on the power line for my UPS,
> which has my PC hooked through it. I've got the AC power lines for all
> the TVs and base unit for the phones wrapped w/ 12 turns around a toroid.
> And I have an 8 toroid choke on the amplifier's power line.
> Since adding all these chokes, I've gone band by band to see if one is
> worse than the other. Haven't checked 10M since I don't use it. On 15M,
> my PC locks up and sound comes through the PC speakers. TVI is not too
> bad, and minor interference on the phones. No GFCIs seem to trip. 20M is
> the only band with no problems of any kind. 40 and 80M are the most
> serious. Almost ALL of the problems I described in the second paragraph.
> Major TVI, cuts out the cordless phones, trips GFCIs. But no problem with
> the PC.
> Antenna is Butternut HF6V on the roof of our two story house, and the
> shack is on the lower level. Antenna ground is about 60' of 2x14 romex.
> Don't know what the solid wire equivalent of 3 #14 wires is offhand. But
> it terminates on the opposite side of the house from the station ground,
> clamped to an 8' ground rod driven in 7-1/2'. My station ground system
> has all major components connected to #2 stranded copper wire, about 30'
> total length, which terminates clamped to a 1/2"x8' electrical ground rod,
> driven in to within about 4" of the surface. Nothing else is connected to
> either the antenna or station ground. There is a ground wire for the
> house electrical panel that seems to be #2 stranded copper, but I can't
> tell where it's terminated underground since the ground here is a tad bit
> frozen right now. Everything in the shack connected to AC is on a
> separate circuit run directly to the panel, as is the 220V amp. Rig is a
> FT1000MP Mk 5 and the linear is an Emtron DX-3.
> Hope I haven't overwhelmed you with useless information. I would
> certainly appreciate any advice on the source of this mess, and potential
> cures. Thanks in advance.
> 73, Bob W7BJ
> dit dit
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