[Elecraft] Interference from Computers-Routers

[ROBERT CARROLL]

Hi, Ron-

The "smart home" system was pretty elderly, having been installed about
1983, two owners back.  The house has an alarm system, and when a sensor
detected an intruder, it generated a coded output signal which went to the
box hidden behind the breaker panel.  The box in their generated a 2 part
code that was put on a house wiring carrier signal and injected at the
panel.  The signal went throughout the house on the ac wiring and when it
reached a "smart switch" with the right unit code and house code (maybe they
were worried about doing things by mistake in the house next door) the
switch would turn on a light in the vicinity of the suspected intrusion.
Actually several signals would be sent so that several lights would be
turned on.  There were little bar slides on most of these switches allowing
you to turn off the remote feature if you wanted.  We also discovered a
little remote control allowing you to turn on things remotely if you wanted.
Some of the smart switches included a dimmer which could be operated by the
remote control.  It was the dimmer capability that caused me to send several
things to the dump.  The dimmers were designed for incandescent lights only
drawing 500w or less, but the original electrician had wired them to the
upper socket in many ac outlets.  I guess the idea was to going into a room,
hit the wall switch and use the dimmer to control table lamps plugged into
the upper outlets.  But the dimmer was never designed to handle fluorescents
or switching power supplies, and I destroyed several things before finding I
wanted to dump the "smart" system.

Bob W2WG

-----Original Message-----
From: ron [mailto:roncasa at verizon.net] 
Sent: Wednesday, August 10, 2005 10:31 AM
To: ROBERT CARROLL
Cc: 'Elecraft Reflector'
Subject: Re: [Elecraft] Interference from Computers-Routers

Wow, good work Bob.
Thank you for sharing it with us. I made my wife throw out all (2) the 
touch lamps and removed all "dimmer" switches. (It makes the radio 
"dim") but never thought about the router causing birdies that I do have 
(always on your favorite freqs).
Can you explain what the signal injector behind the panel was for?
Ron wb1hga
(still not entirely noise free, yet)

ROBERT CARROLL wrote:
> I have recently moved to a new QTH and am slowly getting things in shape
to
> get back on the air.  I ran into a lot of nasty RFI problems.  The
previous
> owner had installed "smart house" wall switches throughout the house.
They
> were supposed to control incandescent lamps only, but in fact they
> controlled fans, wall outlets, etc.  Besides sending a few entertainment
> radios to the dump before I figured out what was going on, the RFI was
> horrendous.  Gradually I removed them only to find I still had problems.
> While doing some electrical work an electrician found the signal injector
> for the system behind the main breaker panel, and that eliminated nearly
all
> the noise.
> 
> I should say nearly all the broadband noise, as I was left with birdies
> about every 30 kHz or so.  Eventually I tracked those down to a Linksys
> Wireless G router, model wrt54gs.  My previous Linksys bit the dust just
> before I moved, so I can't say if I would have heard the birdies from this
> one had I installed it in the old QTH.  I have wireless and wired
> connections running off this router, and have helped the problem by
> installing ferrite on the power wart lead and all the data leads.  But I
> have not been able to eliminate the rather broad birdies that seem to fall
> at nice dx frequencies.
> 
> Has anyone on the reflector had such a problem and found a way to cure it?
> Searching on the internet I find that RFI from routers is a well known
> phenomenon, but I have seen no suggestions for curing the problem.  
> 
> 
> Bob W2WG
> 
> 
> 
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Bob - W5BIG
> Sent: Wednesday, August 10, 2005 9:32 AM
> To: tom.w3qs; 'Elecraft Reflector'
> Subject: Re: [Elecraft] Interference from Computers
> 
> Hi Tom,
> 
> One major source of noise is the CRT monitor.  It helps to make the screen
> display as uniform as possible, like a blank window or a plain background
> without texture.
> 
> 73/ Bob - W5BIG
> 
> 
> ----- Original Message -----
> From: "tom.w3qs" <tom.w3qs at verizon.net>
> To: "'Elecraft Reflector'" <elecraft at mailman.qth.net>
> Sent: Wednesday, August 10, 2005 7:03 AM
> Subject: [Elecraft] Interference from Computers
> 
> 
> 
>>Good Morning Group,
>>
>>I am back on the air (4991) after nearly 20 years.  The first thing I
>>noticed was all the interference on 20 meters.  Hetrodynes everywhere!
>>What's going on?
>>
>>Took me a while to figure out that it was the computer - not there 20
> 
> years
> 
>>ago!
>>
>>So, other than removing it from the shack (ghastly thought) is there any
>>font of wisdom on this subject or general guidance?
>>
>>Thanks and 73,
>>
>>Tom, W3QS
>>
>>
>>_______________________________________________
>>Elecraft mailing list
>>Post to: Elecraft at mailman.qth.net
>>You must be a subscriber to post to the list.
>>Subscriber Info (Addr. Change, sub, unsub etc.):
>> http://mailman.qth.net/mailman/listinfo/elecraft
>>
>>Help: http://mailman.qth.net/subscribers.htm
>>Elecraft web page: http://www.elecraft.com
>>
> 
> 
> 
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft    
> 
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
> 
> 
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft    
> 
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>