[RFI] Zoom X6 DSL Modem loses internet connection

Roger Parsons ve3zi at yahoo.com
Fri Feb 13 19:59:40 EST 2009

I finally got DSL out in the sticks here a couple of weeks ago, and of course more than 100W killed my modem too. Winding the phone line round a toroid helped a bit but not enough - the reasons for that are well known, but it's the easy first thing to try!  I then built a simple filter, the schematic of which I got from G3PQA, but I believe it was an OK station who actually designed it. (Apologies for lack of proper credit.) As I can't put a drawing on here, I will attempt to describe it:

It is a balanced filter with two series inductors in each leg and parallel capacitors at input, output and mid point. All four inductors are 6.51uH (I used 6.8uH). The input and output capacitors are 4.53nF (I used parallel 2.2nF). The centre capacitor is 6.37nF (I used parallel 3.3nF).

I built it in a telephone connection box which gave me 8 places to fix components - no pcb. It works like a charm and I can't detect any difference in connection speed with it in or out of circuit (~5M).

Hope that helps.

73 Roger


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