LF
Quoting James Moritz <[email protected]>:
> On receive, it is something of a problem on 500kHz - positioning a loop
> antenna within about 10m of the phone wire and modem reveals a high level of
> white noise-like QRM. Unplugging the modem makes this dissapear. winding the
> incoming phone wire onto a ferrite core to produce a common-mode choke
> yields about 10dB noise reduction.
I thought I should comment on this since I have fought the same battle with a
very similar experience. I also made a few additional changes that clearly made
a difference as well:
1. Common mode choke at the ADSL modem phone line inlet
2. Common mode choke at the power inlet of the ADSL modem
3. Changed the old 15 metre untwisted, 5-wire in-house telephone cable to CAT5
(any twisted pair type would probably work)
All of the above yielded a noticeable improvement. Improvements were made in the
listed order. Choking off the outgoing ethernet CAT5 from the ADSL modem did not
provide any noticeable improvement.
The ADSL modem/router in my case is a Cisco 837.
BR
Paul-Henrik / OH1LSQ
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