Joe (no callsign given) wrote:
Computers are also extremely noisy! When operating HF I never use a computer, every one I have ever had or used, adds at least 10 DB to the noise floor.
Wayne replies:
How close are your HF antennas to you computers? I don't notice an increase in the HF noise level from the computers in my house, but my HF vertical and HF dipole feedpoint are both 60 feet from the house (and even further from neighbor's houses). At the closest point the dipole's wire is less than 30 feet from two computers in the house.
Do you use CRT monitors with your computers? I found that CRT monitors generate much more RF noise than the average home computer. LCD monitors produce far less RFI. Weak-signal ham operators should NEVER use CRT monitors.
Wayne Estes W9AE Oakland, Oregon, USA, CN83ik
On Wed, 23 Jan 2008 14:23:49 -0600, Wayne Estes wrote:
Computers are also extremely noisy! When operating HF I never use a computer, every one I have ever had or used, adds at least 10 DB to the noise floor.
I use an old IBM PS/2 Server 95 (microchannel) computer w/IBM 6091-19i workstation monitor for logging. It won't run modern games, but it's the most RFI-tight computer I've ever seen.
An AM "Walkman" type of portable radio can be handy for DFing RFI. The loopstick antenna has very sharp nulls. "Calibrate" it using a signal from an AM broadcast station with known (local) location.
73
-Jim
-- Ham Radio NU0C TR7/RV7, TR6/RV6, T4XC/R4C, L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time!
HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/
On Jan 23, 2008, at 8:13 PM, Jim Shorney wrote:
On Wed, 23 Jan 2008 14:23:49 -0600, Wayne Estes wrote:
Computers are also extremely noisy! When operating HF I never use a computer, every one I have ever had or used, adds at least 10 DB to the noise floor.
I use an old IBM PS/2 Server 95 (microchannel) computer w/IBM 6091-19i workstation monitor for logging. It won't run modern games, but it's the most RFI-tight computer I've ever seen.
Metal case? The old steel PC cases are the best RFI shielding they ever had. The new plastic cases with what equates to aluminum foil on the inside, generally suck.
The metal cases are getting hard to find, but you can still buy some metal cases and put modern motherboards in them, too. Then run the station ground to the case, too.
-- Nate Duehr, WY0X nate@natetech.com
I have a couple IBM Thinkpads that have metal cases. Extremely clean! At work I recently bought a T61 Lenovo so we will have to test it. At home I have a brand new Dell Vostro 2.33GB duoCore with 2GB memory and 20-inch LCD display. I'll let you know how it compares. MY old Dell Dim 4100 PS radiates spurs on 2m. Time for some ferrite chokes.
73 Ed - KL7UW
At 08:10 PM 1/23/2008, Nate Duehr wrote:
On Jan 23, 2008, at 8:13 PM, Jim Shorney wrote:
On Wed, 23 Jan 2008 14:23:49 -0600, Wayne Estes wrote:
Computers are also extremely noisy! When operating HF I never use a computer, every one I have ever had or used, adds at least 10 DB to the noise floor.
I use an old IBM PS/2 Server 95 (microchannel) computer w/IBM 6091-19i workstation monitor for logging. It won't run modern games, but it's the most RFI-tight computer I've ever seen.
Metal case? The old steel PC cases are the best RFI shielding they ever had. The new plastic cases with what equates to aluminum foil on the inside, generally suck.
The metal cases are getting hard to find, but you can still buy some metal cases and put modern motherboards in them, too. Then run the station ground to the case, too.
-- Nate Duehr, WY0X nate@natetech.com
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
73, Ed - KL7UW ====================================== BP40IQ 50-MHz - 10-GHz www.kl7uw.com 144-EME: FT-847, mgf-1801, 4x-xpol-20, 185w DUBUS Magazine USA Rep dubususa@hotmail.com ======================================
From Joe WB9SBD
if i'm listening to a dead quiet band, and i turn on a computer, any computer, I hear the difference. weak signals WILL be masked.
My local club was operating CQ world wide DX contest just last year. State of the art systems all around. Great antennas multi monobanders all at 100 feet plus.
They had the station networked with computers, for logging duping etc. when i got there do do my shift in the contest, they all complained how dead the bands were. i got on, and in a half hour agreed that we were not hearing hardly anything. BUT
as soon as we shut down the puters, we sat on one freq and started running a pile up of JAPAN Stations, qso rate was in excess of 120 per hour minimum. we were paper logging then,
then someone turned the puters back on, for logging and duping and the qso rate immediately dropped to less than 30 per hour we were just NOT hearing them anymore,, again shut it down and the qso rate doubled if not tripled.
now everyone in our club is a believer and never runs a computer when operating on any band.
Wayne Estes wrote:
Joe (no callsign given) wrote:
Computers are also extremely noisy! When operating HF I never use a computer, every one I have ever had or used, adds at least 10 DB to the noise floor.
Wayne replies:
How close are your HF antennas to you computers? I don't notice an increase in the HF noise level from the computers in my house, but my HF vertical and HF dipole feedpoint are both 60 feet from the house (and even further from neighbor's houses). At the closest point the dipole's wire is less than 30 feet from two computers in the house.
Do you use CRT monitors with your computers? I found that CRT monitors generate much more RF noise than the average home computer. LCD monitors produce far less RFI. Weak-signal ham operators should NEVER use CRT monitors.
Wayne Estes W9AE Oakland, Oregon, USA, CN83ik
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (5)
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Edward Cole -
Jim Shorney -
Joe -
Nate Duehr -
Wayne Estes