On Wed, 14 Jan 2004 00:48:03 -0700, "diddo"
wrote:

Everytime I turn on my Pentium-4 PC, my shortwave signal gets completely
buried behind the noise. Beside shutting off the computer, what can I do to
eliminate this noise?

Thanks

The usual culprit is the monitor. Most of the Big ones are class
A,not Class B, and I have never seen a Class monitor that actually
operated within the Class A FCC limits (and I've been out on a test
range many times). The other possible source is the switching power
supply, but most of them are very heavily shielded if the computer is
class B. (All laptops are class B, and in theory anything designed for
home use is class B).

Everything else operates at clock frequencies far beyond the HF
bands.

CRT monitors however user a very high power saw tooth to drive the
sweep, and you can think of it as a very messy 100Khz calibrator. Most
are on the order of 100Khz, and the wave form is very rich in
harmonics (do a fourier analysis on a saw tooth), and the output of
the Horizontal osicillator is usually tens of watts, so even if the
harmonics in the SW band are 50 db down, that is a lot of power next
to a shortwae that is trying to receive nanowatts.

So get yourself an LCD display.