date:10 dec 2008
ATt Uverse RFI (another fix)

[]I fashioned a choke with 9 bifilar turns 
> of wire on a FT 240-43 core and placed it inside the outside service 
> box. It was apretty tight fit, but I found room. 
> 
> We just got done testing on 160, 80, & 40 meter with power levels up 
> to the legal limit. No problems were observed so far. 
> 
> My antenna is about 60 feet or so from the neighbors. 
> 

[] RFI, although only on 160. Here's the story in a nutshell. The FT 243-43 
> choke kept me out on all bands except 160 when running more than about 400 
> watts. 
> 
> 
> I tried choking all the lines in and out of the modem and receivers (Type 
> 31 ferrite). Still had the problem on 160. Yesterday morning ATT came 
> out, changed out all the CAT 5 cable with shielded Cat 5 cable. ATT will 
> use the shielded CAT5 cable from the service drop to the modem, at no 
> extra charge. They refer to this run of cable as the "Home Run". Still I 
> had the problem on 160. So now I am thinking that somehow I am getting 
> into the telephone lines going down the poles on my road. 
> 
> They called in a line tech and he checked the line at the drop from my 
> neighbors pole to his house. There were signs of RF there (lots of FEC 
> errors). They were about ready to just say well there's nothing they can 
> do. At that point I mentioned I had an old overhead drop to my house which 
> is disconnected on my end (I use cable TV and Vonage). The line tech came 
> over to look at my pole and sure enough the old overhead drop was still 
> connected at the pole. He disconnected the old overhead drop at the pole 
> end. His equipment was now showing a decrease in errors by a factor of 
> 100. 
> 
> So I took off all the chokes on the lines into the modem, and receivers, 
> and the one at the service drop. Now I could run almost a KW on 160. Put 
> the choke back on at the service drop into the house, and now I could run 
> the legal limit on 160 without a problem. I tested it, with a bit over the 
> legal limit just to make sure. HiHi 
> 
> After the ATT guys left, I went over and paced off the length of my old 
> overhead drop, and guess what, almost a perfect 1/4 wave on 160 ! (about 
> 120 feet, give or take) The old overhead drop was looking like an antenna, 
> and then propagating into the telephone wire bundle (as common mode 
> currents), then coupling with my neighbors twisted pair and and then 
> running into his house. 
> 
> The attached photos show the choke that I put into my neighbors service 
> box. The ATT tech was saying that VDSL signals like solid wire as oppose 
> to stranded wire. I'm not real sure about that claim (his explanation 
> seemed a bit lame), but as I had some solid wire to wind the choke, I 
> decided why tempt fate. I am sure that a bit smaller core (available in 
> 1.9 and 1.4 inch cores) of type 43 material would work and be easier to 
> squeeze into the service entrance box. There are 10 bifilar turns on the 
> choke. 
> 
> I am 99.9 % sure the problem is finally solved, but I will give it a week 
> before I declare it a complete success. 
> 
> 73 
> Roger W8RJ