On 2/3/2012 3:29 PM, Frank Davis wrote: > My own mitigation techniques involved placing a number of 2.4" #31 toroids on > the power cable for the modem and also the VDSL CAT5 cable that feeds the > modem .... I was successful in stopping my line from crashing but only if I > limited my ACOM1010 to 500W out on 160/80/40m.
The difference between 500W and 700W is only 1.5dB, so if it's clean at 500W, it should not take much to make it clean at 700W! > The BellAliant technician told me that placing the ferrites on the CAT5 > feeding the modem caused a significant number ( hundreds of '000's on a > continual basis.) of FEC (forward error correction) events to begin happening > on my line. That does not make sense unless the CAT5 was mechanically distorted by the winding. That would disturb the impedance at bit, but a LOT of errors doesn't make sense to me. The ferrites form a common mode choke, which the differential circuit should not see. > I was not aware of these errors as they did not present themselves on the > TV screens. The service provider did not like these errors on the line and > wanted to eliminate them. Today the techs visited again and placed a new 3 > pair shielded drop wire from the pole to my house. Was it twisted pairs? Twisting is what matters. CAT5/6/7 is very good twisted pair. > After much investigation and trial and error he installed a TII Network > Technologies filter/splitter > (http://www.tiinetworktechnologies.com/repository/datasheetlibrary/NYMDS086-0411.pdf) > at the point where the drop wire enters the wiring closet a few meters from > the shack area. > > He referred to it as a "business filter" meaning it is generally used in > business locations were internet access maybe required at a specific > workstation and not others. It splits the line between POTS and Internet . > Only after this filter was placed did the RFI stop and the line would stay up > when I run 700W from the amp. There are still ferrites on the power cord to > the modem but not on the CAT5 cable to the modem. The techs explanation was > that this robust filter was "blocking" stray RF induced into the house > telephone wiring and CAT5 drops coming back from various parts of the house > to the common terminal block in the wiring closet. Deduced from a couple of > hours of isolating various feeds etc. There is a lot of wire as each room > in the house has a CAT5 cable and a telephone drop and RG6 cable. Good move. 73, Jim K9YC _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
