Thank you Jim. I happen to have a few #31 cores, 2.4in OD. At the
computer end of the ethernet cable I began threading the cable through
the core and made some observations along the way as I measured the
birdie at 14015KHz on the S meter of my ICOM IC-7800:
turns 0, S-meter reading S 8.5
turns 1, S-meter reading S 8.5
turns 2, S-meter reading S 7.5
turns 3, S-meter reading S6
turns 4, S-meter reading S4
turns 5, S-meter reading S2
turns 6, S-meter reading S2
turns 7, S-meter reading S1
turns 8, S-meter reading no S-meter movement, barely audible
There appears to be a similar reduction in birdie level on the other
bands. The birdies are not gone but they are now at a level I can live
with. Wonder if I could get away from them completely by installing a
wireless card in the Dell Inspirion?
Out of curiosity I switched the cable ends and found that putting the 8
turns at the router raised the S-meter reading from no movement to S7.
Evidently the computer is the source of the birdies. So I switched the
cable back to having the 8 turns at the computer.
A second #31 core with 5 turns at the router made no discernible
difference in either S-meter reading or to my ear.
73,
Steve K8JQ
On 6/26/2012 10:24 AM, Jim Brown wrote:
> On 6/26/2012 7:16 AM, Steve wrote:
>> Anyone ran into this kind of thing before? Advice as to how to rid
>> myself of these unwanted signals?
> It's the Ethernet stuff related to the router. The cables are acting as
> transmitting antennas, your ham antennas are receiving the noise. The
> solution is multi-turn ferrite chokes on each of those cables. Five
> turns on a #43 or #31 core will make a nice dent in the noise. See
> http://audiosystemsgroup.com/RFI-Ham.pdf for details, and for part
> numbers and vendors for suitable ferrite cores. EVERY cable can radiate
> the noise, including the power cables, so every cable should be choked.
>
> 73, Jim Brown K9YC
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>
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