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PA2AGA > HDDIG 23.08.00 01:06l 145 Lines 5251 Bytes #999 (0) @ EU
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To : HDDIG@EU
Date: Wed, 23 Aug 00 00:44:43 MET
Message-Id: <hd_2000_228B>
From: pa2aga@pe1mvx.ampr.org
To: hd_broadcast@pa2aga.ampr.org
X-BBS-Msg-Type: B
> regular harmonics) leads me to believe that it is the monitor. Try changing
> the refresh rate and you may verify this. I had the same problem and this
was
> the cure.
>
> 73,
> K2OG
------------------------------
Date: Mon, 21 Aug 2000 23:47:06 -0700
From: "Greg D." <gregd@jps.net>
Subject: PSK31 reception killed by RFI from PC...
Ok, this sounds just like my situation... Here's what I've found:
P-III 667, Asus motherboard. The chassis is all metal, but it doesn't
matter if the side panels are on or off! The noise is very broad band,
but does peak frequently across the bands. It tapers off above 15
meters, but I can hear it even up into the VHF range.
It's not the monitor, and it's not the motherboard, CPU, video, sound,
etc.
cards. It's the power supply!
I confirmed this by plugging the computer into a different circuit in
the
house via an extension cord. Lower noise. Then I got a couple of line
RFI filters (not surge supressors - they're for a different problem),
and
that helped more, but going from S7 to S5 still leaves me with an S4
size
problem.
The previous computer was an old P90 system from HP, which was totally
quiet. I also have a P200 clone in the same room (same wall plug too),
and it's pretty quiet too, so it's not impossible to do this right.
It looks like I need to get a new power supply. ATX format, 250 watts.
The current unit is from Transworld. Any suggestions for a good QUIET
brand?
Greg.
Steve Kallal wrote:
>
> I am trying to get a PSK31 setup going at home. I am able to get reasonable
> copy with a Sony Vaio laptop, but it belongs to my company and they want it
> back. My desktop machine is definitely not FCC type accepted. It uses a
> SuperMicro main board with a PIII 550 MHz CPU. I assembled it myself with
> generic parts from a local comptuer store. When ever I turn the desktop PC
> on, my receiver on 20 meters get several S units of noise covering all but
> the strongest signals. When I disconnect the antenna the noise disappears
> completely. The rig is around the room from the computer, about 6 to 8 feet
> or so. The antenna is located on the my apartment balcony at least 15 to 20
> feet away.
>
> My gut feeling is that the PC is not worth the trouble of trying to clean
> up. Perhaps I should try other PCs or find an older Pentium type laptop.
> Would buying a name brand PC with some sort of FCC type acceptance help.
> Does anyone have any suggestions? I am open to ideas.
>
> Steve Kallal KB9XU
> skallal@pacbell.net
------------------------------
Date: Tue, 22 Aug 2000 10:40:12 GMT
From: hamish@cloud.net.au (Hamish Moffatt VK3SB)
Subject: PSK31 reception killed by RFI from PC...
Greg D. <gregd@jps.net> wrote:
> It looks like I need to get a new power supply. ATX format, 250 watts.
> The current unit is from Transworld. Any suggestions for a good QUIET
> brand?
I had terrible power supply noise here; 80m was completely unusable.
The thing even whined audibly when switched off (stand by really).
I replaced it with another one from the clone shop and it's been fine.
Just lucky I guess. The new one seems to have variable fan speed,
which is an added bonus.
Hamish
--
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>
------------------------------
Date: Sun, 13 Aug 2000 14:52:27 GMT
From: Marc Passy <laikaservices@yahoo.com>
Subject: Stupid Question
Bob Lewis wrote:
>
> > A couple of documents made a real point of differentiating
> > between the data rate between the computer/TNC and the
> > TNC to the radio, as if they could ever be effectively different
>
> They usually are different. The TNC to Radio baud rate may be 1200
> baud while the TNC to Computer (serial port) baud rate is usually much
> higher (9600, 19.2, etc). The serial port uses a handshake (hardware
> or software) to control the flow of data from the computer and prevent
> the buffers in the TNC from overflowing. A higher baud rate is used on
> the serial port in order to quickly fill up a packet during file
> transfers so it can get transmitted by the TNC. That improves the
> throughput. The total throughput is limited by the radio side though.
> The throughput for 1200 baud is less than 1200 baud because of the
> packet overhead (addressing, CRC check, etc). The more "real data" you
> can stuff into a packet, the more efficient it is.
So, in other words, the instantaneous datarate from Computer to TNC
should be higher that the radio DR, but the long term, effective
datarate will be dictated by the radio side, right?
--
To reply, remove two pounds of spam-proofing.
My Opinions are all my own. Nobody else, especially the
people I work for, wants to claim them.
"At the core of the risk-free society is a self-indulgent failure of
nerve."
Edwin "Buzz" Aldrin, 1999
------------------------------
End of Ham-Digital Digest V2000 #228
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