[comp.sys.next] RF on NeXT

c252-ag@cinna.berkeley.edu (James C. Lee) (02/06/91)

In <1991Feb5.064037.10135@macc.wisc.edu> Andrew wrote:

> Oh, what are people's experience with the amount of RF given off by the
> NeXT?  How does it affect TV's and radios?

Here's a non-scientific test. I have a Cobra cordless phone at home. In
the past when I talk on the phone with either my IBM PS/2 or IBM clone on,
some static noise was always present. However, to my pleasant surprise,
having my cube on has *no* effect on the quality of the phone! Maybe the
magnesium cases really does its work?! :-)


---------------------------------------------------------------------------
James C. Lee, NeXT Campus Consultant - University of California at Berkeley
email: jclee@cory.berkeley.edu
Disclaimer: Unless otherwise specified, none of the above reflects the
policies of NeXT Computer, Inc.  Likewise, the above does not commit
NeXT to any specific course of action nor can anything I say be
construed as binding on NeXT.  All opinions are my own.

rbp@investor.pgh.pa.us (Bob Peirce #305) (02/14/91)

In article <10819@pasteur.Berkeley.EDU> c252-ag@cinna.berkeley.edu (James C. Lee) writes:
>
>In <1991Feb5.064037.10135@macc.wisc.edu> Andrew wrote:
>
>> Oh, what are people's experience with the amount of RF given off by the
>> NeXT?  How does it affect TV's and radios?
>
>Here's a non-scientific test. I have a Cobra cordless phone at home. In
>the past when I talk on the phone with either my IBM PS/2 or IBM clone on,
>some static noise was always present. However, to my pleasant surprise,
>having my cube on has *no* effect on the quality of the phone! Maybe the
>magnesium cases really does its work?! :-)
>
I have a Panasonic phone with the transmitter/receiver on a desk above
the cube.  The cube does not affect this.  However, I do get noise on
the handset when sitting at the desk, a foot or so away from the
receiver, the cube and the VDT.  The cube is in a room with a lot of
sensitive audio equipment, including a low output moving coil cartridge.
There is no noticable noise on the audio system.  I don't know if the
noise on the handset is from the cube or the VDT.
-- 
Bob Peirce, Pittsburgh, PA				  412-471-5320
...!uunet!pitt!investor!rbp			rbp@investor.pgh.pa.us

cyliao@eng.umd.edu (Chun-Yao Liao) (02/17/91)

In article <10819@pasteur.Berkeley.EDU> c252-ag@cinna.berkeley.edu (James C. Lee) writes:
>
>In <1991Feb5.064037.10135@macc.wisc.edu> Andrew wrote:
>
>> Oh, what are people's experience with the amount of RF given off by the
>> NeXT?  How does it affect TV's and radios?

	NeXT is VERY "quiet" at RF. See, we have a tiny little room
	that I share with my roommate. He has a color TV. Since the room
	is so small, the TV set is only 1 metter and half. It never give
	any trouble to TV's reception. A while back, we started to experience
	interfarence... and my roommate was mad of me because I didn't agree
	to shut down my CuBE, Ok, so I finally shut my cube down in front of
	him, and guess what, the inteference continues.
	
	We found the origin of the interference later. It was from my modem!
	Yes! The little modem I have! it's only about 3x4x1 inch

--
cyliao@bagend.eng.umd.edu       o Q. Who am I?
      @wam.umd.edu      	o A. A NeXTed person with "small" HD and OD
      @epsl.umd.edu		o    An Apple // guy
xxxxxx@xxxxxx.xxxx.xxxxxxx.xxx	o    An airplane pilot (I hope)

ifjrs@acad3.alaska.edu (STANNARD JOHN R) (02/18/91)

In article <1991Feb13.210116.25168@investor.pgh.pa.us>, rbp@investor.pgh.pa.us (Bob Peirce #305) writes...
>In article <10819@pasteur.Berkeley.EDU> c252-ag@cinna.berkeley.edu (James C. Lee) writes:
>>
>>In <1991Feb5.064037.10135@macc.wisc.edu> Andrew wrote:
>>
>>> Oh, what are people's experience with the amount of RF given off by the
>>> NeXT?  How does it affect TV's and radios?
>>


I'm an Amateur Radio Operator running a packet-radio bulletin
board.  I've got four-to-five radios all running 24 hrs/day, a
phone modem at least turned on most of the time; I'm running the
TNCs (radio modems) on 2 cards in a 386 machine, and sometimes an
external TNC as well.  I also have an answering machine.

This means that (when my NeXT is also on) I have two computers,
two monitors, a phone modem, and usually 5 radios on.  _Once_ in
a while, if the phone modem is turned on but not on-line, I get
a bit of heterodyne on one of the radios.  Other than than, the
only interference I'm getting is from the NeXT PRINTER!

All these machines are within approx. 8 feet or closer--my
tables are in an L-shape.  As a result, when I first bring up
the NeXT, I usually get into Shell and 'su,' then type:
	nppower off
then exit.

This, of course, turns off the printer until I have a need for it,
and does away with any RF getting into my radios (or the other
computer monitor, for instance).  Incidentally, the radios are
all grounded, the computer systems are NOT.  You might want to
try various grounding schemes to avoid any ground-loops.  BTW,
the radios (which transmit at various intervals) have not bothered
the NeXT, either...the only time it did odd things (moved my
cursor around a bit) to the MegaPixel Monitor was when I happened
to have an inadvertant high SWR on one of the radios...when I
adjusted that with a tuner, it stopped affecting my screen.

Hope this helps alleviate any fears of the NeXT putting out any
significant amount of RF (DON'T WORRY ABOUT THE FCC 'A' RATING!
The 'B' rating is in the works, I understand...it just takes some
time!).

John
--

John Stannard
KL7JL@KL7JL	IFJRS@ACAD3.FAI.ALASKA.EDU	BITNET: IFJRS@ALASKA
kl7jl.ampr.org   "God is the Answer!"  "Oh?? ... er, ...What was the Question?"


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