Qualtek makes a neat little filter designed to replace the power input
connector on a noisy supply. It fit into mine - one of those with the
jumpered filtering components - and completely suppressed any audible
noise. According to the schematic on the side, it consists of 2 x 2.5
mH indutors, one in series with each leg, a 2200 pF cap shunting the
line input and 0.1uF capacitors from each leg to ground on the load
side. Their part number is 858-03/007, and I got mine at Mouser.
73, Pete N4ZR
The World Contest Station Database, atwww.conteststations.com
The Reverse Beacon Network athttp://reversebeacon.net, blog at
reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000 and
arcluster.reversebeacon.net, port 7000
On 7/4/2012 12:14 PM, Jim Brown wrote:
> On 7/4/2012 6:10 AM, Bill Cromwell wrote:
>> Next I'll be getting my hands on some ferrite core materials and looking to
>> see just how far I can reduce the noise.
> When faced with a noisy computer, the first thing I'd try (other than
> replacing the noisy supply) would be a multi-turn choke on the power
> cable, optimized (number of turns and core) for the band(s) where you're
> hearing the most noise. If noise remained, I'd next tackle the video
> cable and the printer cable. Use the graphs in Appendix One of
> http://audiosystemsgroup.com/RFI-Ham.pdf as a guide to picking the cores
> and winding the chokes.
>
> Do your fellow hams another favor -- post the brand names and/or vendors
> of both the noisy power supply and the one that fixed your problem (if
> it does). :)
>
> 73, Jim K9YC
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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