I agree with both of these suggestions. CAT5 makes great telephone
cable if you use one pair per line. The only thing I would change is to
use even more turns on the ferrite choke(s) and I would place them close
to the phones that are ringing. FWIW, modern wired phones are notorious
for RFI. This is another problem that can often be solved or minimized
by the use of a UHF wireless system, in this case, a base station and
multiple "walk around" handsets. We've been using a Panasonic system for
about five years, and another system with fewer handsets for years
before that.
All it takes to install a system like this is to plug the base station
into one of the wired outlets. Most are powered from the telephone line
or a wall wart. The model we bought at Costco uses one of the handsets
plugged into the base station for battery backup. With this RFI problem,
I'd plug it in with as little wiring as possible to where the wired line
enters the home and disconnect other wiring from it (doing so in manner
that it can easily be restored). And I would put a choke one the line to
that base station. The wall wart is probably an SMPS that will create
RFI, so should be replaced by an old linear supply.
In doing the research for telephone chokes/filters that I incorporated
into RFI-Ham, I obtained several popular filters that were built and
sold by hams and measured them. The results are shown in Fig 28 on page
19. All of these filters are common mode chokes, and all have choking Z
greater than 10,000 ohms across the bands they cover. One has a choking
Z greater than 20,000 ohms on the AM BC band.
73, Jim K9YC
On 11/19/2017 9:19 AM, Dave Hachadorian wrote:
If ALL of the phones are ringing, I suspect the Comcast box is telling them to
ring. I would try a good K9YC 80 meter choke on the phone line right where it
comes out of the Comcast box. Then I would also try one of those same chokes
on the power supply going to the Comcast box.
On 11/19/2017 8:52 AM, Augie "Gus" Hansen wrote:
Hi Steve,
If any phones in his home have extension cables they are likely using
parallel wires, not twisted pair. Replacing such extensions with
quality UTP cable goes a long way toward curing this type of RFI.
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