Computer Noise Poll

tgstewart at tgstewart at
Tue Jan 14 10:46:26 EST 1997

I recently assembled a new computer from parts, using an IBM P150+ (Pentium
clone) processor and discoverd to my horror that it is generating huge
amounts of RF in the ham bands, particularly on 160 meters.  By huge I'm
talking about S9 +10 garbage on 160 in several places, with antennas a
couple hundred feet away and the computer/shack in the basement!  By
process of elimination (ie unpluging almost everything), I've narrowed it
down to the motherboard and/or processor.  My 486/66 by comparison is quiet
as a church mouse, even with the case open, and a 386DX25 is relatively
quiet as well.

So I'd like to hear from all contesters using Pentium/Pentium clone
(Cyrix/IBM)  machines and let me know if you have significant interference
or not, the make/model of your motherboard, the type of processor you are
using, and clock speed.

73, Tyler K3MM

>From bhorn at (Bruce Horn)  Tue Jan 14 16:40:31 1997
From: bhorn at (Bruce Horn) (Bruce Horn)
Date: Tue, 14 Jan 1997 08:40:31 -0800
Subject: Contest Calendar 97.1
Message-ID: <v02140b00af00f6f49c5d@[]>

                              CONTEST CALENDAR
                         January 13, 1997 Edition (97.1)

Please send corrections and additions directly to me.  I will post an
updated calendar on a monthly basis.  Thanks to K6ZZ, PA3BFM, VE2PIJ,
NL7TB and N4MIO for contest info.

An HTML version of the calendar is available on request, or the most recent
calendar may soon be found at:

73 de Bruce, WA7BNM   (bhorn at

The contest calendar is divided into two sections:
  1) CONTEST CALENDAR: Calendar showing dates and times of scheduled
  2) CONTEST LOG SUBMITTAL DEADLINES: Deadlines and addresses for
                       submitting logs for contests that have
                       already occurred or whose deadline will pass
                       before the next issue of the calendar.

Please note that you may not be able to operate during all of the total
hours of the contests listed below. Total operating time may also vary
by entry category. See individual contest rules for allowed operating

January, 1997

  North Amer. QSO Party, Phone   1800Z, Jan 18 to 0600Z, Jan 19
  ARRL January VHF Sweepstakes   1900Z, Jan 18 to 0400Z, Jan 20
  CQ 160-Meter Contest, CW       2200Z, Jan 24 to 1600Z, Jan 26
  REF Contest, CW                0600Z, Jan 25 to 1800Z, Jan 26
  UBA Contest, Phone             1300Z, Jan 25 to 1300Z, Jan 26

February 1997

  Delaware QSO Party             1700Z, Feb 1 to 0500Z, Feb 2 and
                                   1300Z, Feb 2 to 0100Z, Feb 3
  North American Sprint, Phone   0000Z-0359Z, Feb 2
  IDRA WW RTTY WPX Contest       0000Z, Feb 8 to 2400Z, Feb 9
  Dutch PACC Contest             1200Z, Feb 8 to 1200Z, Feb 9
  Asia-Pacific Sprint (CW)       1230Z-1430Z, Feb 8
  YL-OM Contest, Phone           1400Z, Feb 8 to 0200Z, Feb 10
  RSGB 1.8 MHz Contest, CW       2100Z, Feb 8 to 0100Z, Feb 9
  North American Sprint, CW      0000Z-0359Z, Feb 9
  ARRL Inter. DX Contest, CW     0000Z, Feb 15 to 2400Z, Feb 16
  CQ 160-Meter Contest, Phone    2200Z, Feb 21 to 1600Z, Feb 23
  North Carolina QSO Party       1200Z-2359Z, Feb 22 and
                                   1200-2359Z, Feb 23
  REF Contest, SSB               0600Z, Feb 22 to 1800Z, Feb 23
  UBA Contest, CW                1300Z, Feb 22 to 1300Z, Feb 23
  YL-OM Contest, CW              1400Z, Feb 22 to 0200Z, Feb 24
  RSGB 7 MHz DX Contest, CW      1500Z, Feb 22 to 0900Z, Feb 23

March 1997

  ARRL Inter. DX Contest, Phone  0000Z, Mar 1 to 2400Z, Mar 2
  RSGB Commonwealth Contest,CW   1200Z, Mar 8 to 1200Z, Mar 9
  Wisconsin QSO Party            1800Z, Mar 9 to 0100Z, Mar 10
  Bermuda Contest                0001Z, Mar 15 to 2400Z, Mar 16
  BARTG WW RTTY Contest          0200Z, Mar 15 to 0200Z, Mar 17
  Russian DX Contest             1200Z, Mar 15 to 1200Z, Mar 16
  Virginia QSO Party             1800Z, Mar 15 to 0500Z, Mar 16 and
                                   1100Z, Mar 16 to 0200Z, Mar 17
  Alaska QSO Party               0000Z, Mar 22 to 2400Z, Mar 23
  CQWW WPX Contest, Phone        0000Z, Mar 29 to 2400Z, Mar 30

April 1997

  SP DX Contest, CW              1500Z, Apr 5 to 2300Z, Apr 6
  EA RTTY Contest                1600Z, Apr 5 to 1600Z, Apr 6
  Holyland DX Contest            1800Z, Apr 5 to 1800Z, Apr 6
  Japan Int.DX Contest, 20-10m   2300Z, Apr 11 to 2300Z, Apr 13
  UBA HF 80m Contest             0700Z-1100Z, Apr 13
  ARRL 144-MHz Spring Sprint     1900-2300 local, Apr 14
  YU DX Contest                  1200Z, Apr 19 to 1200Z, Apr 20
  SP DX RTTY Contest             1200Z, Apr 19 to 2400Z, Apr 20
  EU Spring Sprint, SSB          1500Z-1859Z, Apr 19
  ARRL 222-MHz Spring Sprint     1900-2300 local, Apr 22
  Hevetia Contest                1300Z, Apr 26 to 1300Z, Apr 27
  Ontario QSO Party              1800Z, Apr 26 to 1800Z, Apr 27
  ARRL 432-MHz Spring Sprint     1900-2300 local, Apr 30

May 1997

  Texas QSO Party                1400Z, May 3 to 2200Z, May 4
  ARI International DX Contest   2000Z, May 3 to 2000Z, May 4
  FISTS CW Club Spring Sprint    1700Z-2100Z, May 10
  ARRL 902/1296/2304 Sprg Sprnt  1900-2300 local, May 10
  EU Spring Sprint, CW           1500Z-1859Z, May 17
  ARRL 50-MHz Spring Sprint      2300Z, May 17 to 0300Z, May 18
  CQ WW WPX Contest, CW          0000Z, May 24 to 2400Z, May 25

June 1997

  IARU Reg 1 Field Day, CW       1500Z, Jun 7 to 1500Z, Jun 8
  TOEC WW Grid Contest, SSB      1200Z, Jun 14 to 1200Z, Jun 15
  Asia-Pacific Sprint (SSB)      1230Z-1430Z, Jun 14
  ARRL June VHF QSO Party        1800Z, Jun 14 to 0300Z, Jun 16
  All Asian DX Contest, CW       0000Z, Jun 21 to 2400Z, Jun 22
  SMIRK QSO Party                0000Z, Jun 21 to 2400Z, Jun 22
  ARRL Field Day                 1800Z, Jun 28 to 2100Z, Jun 29

July 1997

  RAC Canada Day Contest         0000Z-2400Z, Jul 1
  Venezuelan Ind.Day Contest,SSB 0000Z, Jul 5 to 2400Z, Jul 6
  IARU HF World Championship     1200Z, Jul 12 to 1200Z, Jul 13
  CQ Worldwide VHF Contest       1800Z, Jul 12 to 2100Z, Jul 13
  Colombian Indep. Contest       0000Z-2400Z, Jul 19
  SEANET WW DX Contest, CW       0001Z, Jul 19 to 2359Z, Jul 20
  South Pacific 160m Contest     0500Z-2359Z, Jul 19
  Venezuelan Ind.Day Contest,CW  0000Z, Jul 26 to 2400Z, Jul 27
  IOTA Contest                   1200Z, Jul 26 to 1200Z, Jul 27

August 1997

  European HF Championship       1000Z-2200Z, Aug 2
  North Amer. QSO Party, CW      1800Z, Aug 2 to 0600Z, Aug 3
  ARRL UHF Contest               1800Z, Aug 2 to 1800Z, Aug 3
  WAE DX Contest, CW             0000Z, Aug 9 to 2400Z, Aug 10
  SARTG WW RTTY Contest          0000Z, Aug 16 to 1600Z, Aug 17
  SEANET WW DX Contest, SSB      0000Z, Aug 16 to 2359Z, Aug 17
  Keyman's Club of Japan Contest 1200Z, Aug 16 to 1200Z, Aug 17
  W/VE Islands Contest           1700Z, Aug 16 to 2300Z, Aug 17
  North Amer. QSO Party, Phone   1800Z, Aug 16 to 0600Z, Aug 17
  ARRL 10 GHz Cumul. Contest     0800-2000 local time, Aug 17 and Aug 18
  TOEC WW Grid Contest, CW       1200Z, Aug 30 to 1200Z, Aug 31

September 1997

  All Asian DX Contest, SSB      0000Z, Sep 6 to 2400Z, Sep 7
  IARU Reg 1 Field Day, SSB      1500Z, Sep 6 to 1500Z, Sep 7
  North American Sprint, CW      0000Z-0359Z, Sep 7
  WAE DX Contest, SSB            0000Z, Sep 13 to 2400Z, Sep 14
  ARRL September VHF QSO Party   1800Z, Sep 13 to 0300Z, Sep 15
  North American Sprint, Phone   0000Z-0359Z, Sep 14
  Washington State Salmon Run    1200Z, Sep 20 to 0700Z, Sep 21 and
                                   1200Z-2400Z, Sep 21
  ARRL 10 GHz Cumul. Contest     0800-2000 local time, Sep 20 and Sep 21
  Scandinavian Act. Contest, CW  1500Z, Sep 20 to 1800Z, Sep 21
  CQ Worldwide DX Contest, RTTY  0000Z, Sep 27 to 2400Z, Sep 28
  Scandinavian Act. Contest, SSB 1500Z, Sep 27 to 1800Z, Sep 28

October 1997

  VK/ZL/Oceania Contest, Phone   1000Z, Oct 4 to 1000Z, Oct 5
  EU Autumn Sprint, SSB          1500Z-1859Z, Oct 4
  California QSO Party           1600Z, Oct 4 to 2200Z, Oct 5
  RSGB 21/28 MHz Contest, SSB    0700Z-1900Z, Oct 5
  VK/ZL/Oceania Contest, CW      1000Z, Oct 11 to 1000Z, Oct 12
  EU Autumn Sprint, CW           1500Z-1859Z, Oct 11
  Pennsylvania QSO Party         1600Z-2400Z, Oct 11 and 0000Z-0500Z and
                                   1300Z-2200Z, Oct 12
  JARTS WW RTTY Contest          0000Z, Oct 18 to 2400Z, Oct 19
  QRP ARCI Fall QSO Party, CW    1200Z, Oct 18 to 2400Z, Oct 19
  Asia-Pacific Sprint (CW)       1230Z-1430Z, Oct 18
  Worked All Germany Contest     1500Z, Oct 18 to 1500Z, Oct 19
  RSGB 21/28 MHz Contest, CW     0700Z-1900Z, Oct 19
  CQ Worldwide DX Contest, SSB   0000Z, Oct 25 to 2400Z, Oct 26

November 1997

  Ukranian DX Contest            1200Z, Nov 1 to 1200Z, Nov 2
  ARRL Sweepstakes, CW           2100Z, Nov 1 to 0300Z, Nov 3
  High Speed Club CW Contest     0900Z-1100Z and 1500Z-1700Z, Nov 2
  Japan Int.DX Contest, Phone    2300Z, Nov 7 to 2300Z, Nov 9
  WAE DX Contest, RTTY           0000Z, Nov 8 to 2400Z, Nov 9
  RSGB 1.8 MHz Contest, CW       2100Z, Nov 15 to 0100Z, Nov 16
  ARRL Sweepstakes, Phone        2100Z, Nov 15 to 0300Z, Nov 17
  CQ Worldwide DX Contest, CW    0000Z, Nov 29 to 2400Z, Nov 30

December 1997

  ARRL 160-Meter Contest         2200Z, Dec 5 to 1600Z, Dec 7
  ARRL 10-Meter Contest          0000Z, Dec 13 to 2400Z, Dec 14
  TARA RTTY Sprint               2100Z, Dec 13 to 0100Z, Dec 14
  RAC Canada Winter Contest      0000Z-2400Z, Dec 28
End of calendar section

Please consult the individual contest rules to determine what log
documentation must be submitted (i.e. summary sheet, dupe sheets, etc.).

  ARRL 10-Meter Contest          January 14, 1997
    E-mail:  contest at
    Mail:  ARRL 10-Meter Contest
           225 Main Street
           Newington, CT  06111  USA

  CQ Worldwide Contest, CW       January 15, 1997
    E-mail:  cw at
    Mail:  CQ Magazine (CQWW CW)
           76 North Broadway
           Hicksville, NY  11801

  TARA RTTY Sprint               January 25, 1997
    E-mail:  MRBILL1953 at
    Mail:  William J. Eddy, NY2U
           2404 22nd Street
           Troy, NY  12180-1901

  Stew Perry Dist.Challenge(160) January 29, 1997
    Mail:  Bill Fisher, KM9P
           1137 Charlie Ln.
           Lilburn, GA  30247-4203  USA

  RAC Canada Winter Contest      January 31, 1997
    E-mail:  (none)
    Mail:  RAC Contest Committee
           720 Belfast Road, Suite 217
           Ottawa, ON  K1G 0Z5

  ARRL RTTY Roundup              February 4, 1997
    E-mail:  contest at
    Mail:  ARRL RTTY Roundup
           225 Main St.
           Newington, CT  06111

  North Amer. QSO Party, CW      February 11, 1997
    E-mail:  w9nq at
    Mail:  Bob Selbrede, K6ZZ
           6200 Natoma Ave.
           Mojave, CA  93501

  Midwinter Contest, CW & Phone  February 11, 1997
    E-mail:  (none)
    Mail:  Midwinter Contest
           P.O. Box 262
           3770 AG Barneveld

  Hunting Lions In the Air       February 15, 1997
    E-mail:  (none)
    Mail:  Contest Committee
           Lions Club Flen
           P.O. Box 106
           642 23 Flen
End of log submittal deadlines

>From broz at (John Brosnahan)  Tue Jan 14 15:50:55 1997
From: broz at (John Brosnahan) (John Brosnahan)
Date: Tue, 14 Jan 1997 09:50:55 -0600
Subject: Computer Noise Poll
Message-ID: <199701141649.AA18094 at>

Tyler, here is a copy of a recent message I sent to Carlos - PY1CAS
and my experience on a number of computers is that the new power 
supplies are the culprit.  The info may be of use to a number of contest
reflectorites so I will also post it there.

Let me know what you find out on your system.   My previous postings 
of similarinfo have resulted in responses confirming my analysis and 
solution.  And any experiences from anyone else has will be helpful.

73  John  W0UN


At 06:33 AM 1/12/97 -0200, you wrote:
>I have just set up my packet station in order to operate "real" assisted in
the ARRL CW next month. We have a gateway in Rio and I can connect AC4ET dx
>However the computer is close to the shack now (of course) and
unfortunately it is generating a considerable noise on all bands.
>Any tips to fix this problem?

Carlos, many of the new computers are omitting the RFI filter in the
power supply that keeps the garbage from the switching mode supply 
from entering the AC mains.  I have had excellent results (as have others
who have taken my suggestion) in virtually eliminating the interference 
by replacing the AC connector on the back of the power supply with an
integrated AC connector and RFI filter such as the Corcom 6EF1.  The
mounting hole for the connector must be widened a few millimeters
on each side--something that can be done with a file in a minute or two.
Just make sure there is enough room behind the connector position
to clear the somewhat longer RFI filter.  In one case that I made the 
modification I needed to bend a capacitor out of the way.

Some power supplies have a place on the circuit board for a filter but have
eliminated the components to save some money, and have just placed
jumpers in the positions where the components had been.  It would
be possible to makea new filter and add it to the exisiting location--or to
add it between the circuit board and the existing connector----but the
commercial Corcom filter is probably the best and easiest way to go.

The commerical filter has 1.0 mH coils (bifilar rated at 6 amps in series
with each side of the line.  On the computer side each side of the AC line 
has 2800 pF to circuit ground.  On the AC mains side of the filter there
is a 9000 pF capacitor across the mains (not to ground).  Just make sure
that you use capacitors that are rated to be installed across the AC

The filters are available from most US electronics suppliers for around
$10 or so, but can often be found in the surplus market for $1-$2.  I used
the 3 amp version (3EF1, a little marginal) because I found some for $1.

There is also a 3EF2 and a 6EF2 that will work and may be even easier
to fit inside the power supply--their terminals come out the top/bottom
rather than the end.

If adding and AC mains RFI filter doesn't completely cure the problem then
additional RFI suppression will be needed--but in my cases (3 computers)
it eliminated the problem.

gl es 73

John  W0UN

John Brosnahan
La Salle Research Corp.
24115 County Road 40
La Salle, CO 80645 USA

voice 970-284-6602
fax   970-284-0979
email broz at

>From hlserra at (H. L. Serra)  Tue Jan 14 17:04:31 1997
From: hlserra at (H. L. Serra) (H. L. Serra)
Date: Tue, 14 Jan 1997 09:04:31 -0800 (PST)
Subject: Req. Info on Eimac Tube Y-826
Message-ID: <Pine.3.89.9701140818.A224-0100000 at>

Anyone have any specs or info on an EIMAC Y-826, datecode 1984, looks 
just like a 3-500Z? If so please reply directly to me and CC addressee 
above. 73, Larry N6NC

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