|[AMRadio] RE:Telephone Wiring RFI Treatment|
W4AWM at aol.com
W4AWM at aol.com
Sun Dec 17 14:39:23 EST 2006
The hum on your phone line is most likely caused by a ground somewhere in the
system. If you have revently installed wiring, there should be a test jack
where the lines come in from outside. Disconnect the plastic plyg from this
jack which isolates your inside telephone wiring. Plug a separate phone into
this jack and listen. If the hum is there, the problem is outside your home and
you shoule call the phone company for service.
If it disappears, the problem is inside your house. If you are paying for
inside wiring service which you shoule be able to detirmnine from your bill, the
phone company service will fix it for free. If you are not paying for
service, you will have to find it yourself or pay the price to the phone company to
find the problem for you which is not exactly cheap.
If you want to find it yourself, oner thing to check is the wall outlets.
Remove them from the wall and determine if there is a greenish blue oxide on the
connector. This sometimes happens when the connector gets damp from
condensation or a leak in the insulation somewhere. If you find this problem, do not
bother trying to clean the connector. The problem will return soon. It is
better to just replace it with a new one.
As far as RFI, there is a very good filter sold by an outfit that advertises
in QST. They are expensive and you will probably need one for each phone, bit
my experience is that they will solve most problems.
You can also go the ferrite bead route on the leads behind the wall or try
with one of the larger ferrite units that snaps apart and you then wrap several
turns of the cable from the wall to the phone around it and snap it closed.
This also work in some instances and are far cheaper that the filters I first
Good luck and let us know what you find.
73 and Top of the Season to you,
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