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1994-11-13
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Date: Fri, 15 Apr 94 04:30:15 PDT
From: Ham-Digital Mailing List and Newsgroup <ham-digital@ucsd.edu>
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: <Ham-Digital@UCSD.Edu>
Send subscription requests to: <Ham-Digital-REQUEST@UCSD.Edu>
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 <Co8ts8.9Bn@world.std.com> 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: <Co7pDA.G2r@cbnewsj.cb.att.com>
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
******************************