Date: Fri, 15 Apr 94 04:30:15 PDT From: Ham-Digital Mailing List and Newsgroup Errors-To: Ham-Digital-Errors@UCSD.Edu Reply-To: Ham-Digital@UCSD.Edu Precedence: Bulk Subject: Ham-Digital Digest V94 #115 To: Ham-Digital Ham-Digital Digest Fri, 15 Apr 94 Volume 94 : Issue 115 Today's Topics: 170 or 200hz shift? 486cpu RFI Problems TCP/IP NOS FAQ? Send Replies or notes for publication to: Send subscription requests to: Problems you can't solve otherwise to brian@ucsd.edu. Archives of past issues of the Ham-Digital Digest are available (by FTP only) from UCSD.Edu in directory "mailarchives/ham-digital". We trust that readers are intelligent enough to realize that all text herein consists of personal comments and does not represent the official policies or positions of any party. Your mileage may vary. So there. ---------------------------------------------------------------------- Date: 14 Apr 1994 00:41:02 GMT From: ihnp4.ucsd.edu!swrinde!cs.utexas.edu!howland.reston.ans.net!vixen.cso.uiuc.edu!prairienet.org!k9cw@network.ucsd.edu Subject: 170 or 200hz shift? To: ham-digital@ucsd.edu The current "standard" for Baudot RTTY and AMTOR is 170 Hz shift. However, PACTOR uses 200 Hz (or at least that is what the German spec calls for). I think that you will find that either shift will work fine. 73, Drew -- *-----------------------------*-------------------------------------* | Andrew B. White K9CW | internet: k9cw@prairienet.org | | ABW Associates, Ltd. | phone/fax: 217-643-7327 | *-----------------------------*-------------------------------------* ------------------------------ Date: Thu, 14 Apr 1994 09:38:42 GMT From: ihnp4.ucsd.edu!swrinde!emory!rsiatl!ke4zv!gary@network.ucsd.edu Subject: 486cpu RFI Problems To: ham-digital@ucsd.edu In article <1994Apr13.183555.17249@newsgate.sps.mot.com> cottle@prism.sps.mot.com (Rick Cottle) writes: >I have been trying to set up a packet station, and have >experienced problems due to a LOT of noise emitted by my >PC. I thought those devices were supposed to be relatively >shielded, but even with an external antenna, my HT pickes >up a lot of noise, which makes squelch settings, etc. >difficult. Common problem. Computers have to meet Class B radiation specs, but that isn't really that quiet when near such an ultra-sensitive receiver as is in a HT (too sensitive in most cases which is why they suffer so much from overload and intermod, but that's another thread). The cure is the usual round of shielding and suppressing, with the additional fillip with a HT that its plastic case is also a lousy shield. The easy part is usually the PC. First start by scraping the paint off of all seams where case parts join so as to get a good electrical connection. Use lots of screws to bond the case together. Typical VHF practice is at least one screw for every two inches of seam. Any openings in the case should be screened with copper screening. The TNC should receive the same treatment since they are usually radiators too. The monitor is usually the worst culprit. Its case needs to be screened since they're usually plastic. There are conductive sprays on the market that work well for this. Usually you'll want to spray the inside of the case for cosmetic reasons. Be careful that any areas of the case that will be close to the HV sections of the monitor are protected by fish paper so that you'll get no flashovers to the now conductive case. If the monitor is color, you should be done since the shadow mask in the CRT makes a good RF shield. However, if the monitor is mono, you may need to put copper screening over the face of the tube. This can serve double duty as a glare shield so its not so bad. Then there's the keyboard. These things have microprocessors in them too, and spray scan code everywhere across the board to scan for keypresses. These can be real bears to quiet. Try the conductive spray on the plastic case, and also tack in bypass caps on the scan lines. You may have to try different keyboards to find one you can quiet. The HT is likely to need additional shielding as well to prevent signals from entering through the case. The conductive spray works here too, or you can put the HT in a shielded metal box. A good input bandpass filter in the antenna lead can help too. Of course *all* interconnecting cabling must be shielded, and in addition, ferrite cores should be placed around cables. This chokes off common mode currents that may be flowing on the shields. In stubborn cases, you may want to relocate the HT to the antenna area and run long shielded and choked AF cables back to the TNC. Getting the too sensitive HT further from the source of computer hash is a very powerful technique to reduce interference. (Or, you could buy a *real* radio, but again that's another thread.) Gary -- Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary 534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244 | | ------------------------------ Date: 14 Apr 1994 11:03:16 GMT From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!noc.near.net!chaos.dac.neu.edu!chaos.dac!wy1z@network.ucsd.edu Subject: TCP/IP NOS FAQ? To: ham-digital@ucsd.edu In article ghitz@world.std.com (George E Hitz) writes: Newsgroups: rec.radio.amateur.digital.misc Path: chaos.dac.neu.edu!grapevine.lcs.mit.edu!olivea!uunet!world!ghitz From: ghitz@world.std.com (George E Hitz) Organization: The World Public Access UNIX, Brookline, MA X-Newsreader: TIN [version 1.2 PL2] References: Distribution: na Date: Thu, 14 Apr 1994 09:45:43 GMT Lines: 20 thomas.kenny (kb2glo@cbnewsj.cb.att.com) wrote: : I'm interested in getting NOS on the air however there seem to be so many : different versions! Does anybody have a FAQ regarding all the different : versions of NOS so I can make an intelligent decision on which one to use. : Thanks and 73, Tom Kenny KB2GLO : -- : Tom Kenny, KB2GLO : UUCP: ...!att!lzusp!tek Internet: tek@lzusp.att.com : Packet Radio: KB2GLO@WT3V.NJ.USA Voice Telephone: 908-576-3888 anonymous ftp to ucsd.edu: hamradio/packet/tcpip/docs/FAQ-1292 is a start on your quest... 73 de George, W1DA -- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% George E. Hitz, jr. W1DA internet: ghitz@world.std.com Sudbury, Massachusetts, USA AX.25: w1da @ wb1dsw.nh.usa.na There is some more stuff on Oakland: /arrl/infoserver/tis: tcp.txt /pub/hamradio/docs/faq: tcpmanual FAQ about KA9Q Inet s/w - 8-May-89 /pub/hamradio/docs/misc: nosbgn20.lp Line Printer formatted TCP/IP help nosbgn20.prn 80 Column formatted TCP/IP help nosbgn20.ps Postscript formatted TCp/IP help Scott -- =============================================================================== | Scott Ehrlich Amateur Radio: wy1z AMPRnet: wy1z@wa1phy.ampr.org | | Internet: wy1z@neu.edu BITnet: wy1z@NUHUB AX.25: wy1z@wa1phy.ma.usa.na | |-----------------------------------------------------------------------------| | Maintainer of the Boston Amateur Radio Club hamradio FTP area on | | the World - ftp.std.com pub/hamradio | =============================================================================== ------------------------------ End of Ham-Digital Digest V94 #115 ******************************