Seems I'm not the only one to have PC noise problems.
Sounds like you do not have a screened cable. Or if you do, the noise
is apparently on the screening braid. Have you tried disconnecting the
screening braid at one end only of the cable, so you do not have an
earth loop ?? I have never had much luck with ferrites, even though I
have them on most of my PC leads. I also have a small stock of ferrite
sleeves that were used on commercial data cables. Unfortunately, the
makers code numbers give no clue as to the RF performance, and I cannot
detect any useful effect from using them. They look good ...
Most of my noise problems came from the monitor, which is necessarily
close to the rig (very small shack). The only solution (not 100%
effective on 30m) has been to acquire a fully metal jacketed
surplus monitor designed for use in very close proximity (stacked
sideways and vertically) with other monitors. Well worth the $75 I paid
for it.
Another prolific noise source may be the PC AC power supply outlet which
supplies the monitor. Some (usually older) rice box PSUs come with
minimal to zero filtering. Properly filtered outlets nake a big
difference..
John G3JAG
On 18-Dec-99 Anthony Bowyer wrote:
>
>
> If, while tuning your Pegasus, you've heard a
> strange signal that sounds like a child's ray gun or a
> sound effect from a bad sci-fi movie, I found out what
> it is. I initially thought it was a birdie, but I
> found out that it's a signal being generated from the
> RS-232 port in the PC that connects to the Pegasus. I
> put a couple of split ferrite chokes on each end of
> the cable and that attenuated the signal, but not as
> much as I'd like. Like most newer motherboards, the
> serial ports are on the motherboard. In my case, there
> are headers on the board, and a piece of ribbon cable
> connects the header to the RS-232 connectors mounted
> on the back of the case. I wound as much of the ribbon
> cable as i could around a toridal core, about 3/4" in
> diameter (they came from old diskless workstations, so
> I'm not sure of their characteristics), and that
> attenuated about 98% of the signal. I can only hear it
> very-very faintly on a few freqs when there are no
> signals.
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E-Mail: John - G3JAG <patents@dx0man.prestel.co.uk>
To: <tentec@contesting.com>
Date: 18-Dec-99
Time: 15:20:41
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