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#83831 - 02/22/03 03:16 PM RF question
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
I am going to be wiring a home for a serious ham radio opertator who will have a dedicated room, and has a motorized (extends to 70') tower already in place.

His wishes include having no RF interference from lighting, dimmers etc.

As i've never run into this reqest and simply do not know where to start i welcome any input

thanx
~S

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#83832 - 02/22/03 03:59 PM Re: RF question
WebSparky Offline
Member

Registered: 02/21/03
Posts: 144
Loc: Cleveland, Ohio
Here is a link to a simplified explanation.
Hope it helps!
http://www.hamradio-online.com/1999/oct/vdsl.html

Dave
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Dave

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#83833 - 02/22/03 05:22 PM Re: RF question
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
Thank you for the link Dave. I suppose proximity of the radio xmitter to the computer and/or associated lines would be a quick fix?

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#83834 - 02/22/03 06:20 PM Re: RF question
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Would an isolated ground be of any help?

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#83835 - 02/22/03 06:49 PM Re: RF question
WebSparky Offline
Member

Registered: 02/21/03
Posts: 144
Loc: Cleveland, Ohio
sparky:

You're welcome.
It seems as though every electrical device has the potential for rf. Keep in mind rf is simply unwanted radio wave (magnetic field) interference. For instance, most magnetic fields that are present in your home do not interfere with other electrical devices. The ones that do are refered to as rf. In the case of a HAM radio, I would be more concerned with rf from local external sources such as high voltage overhead power lines or substations. When the overhead power lines are run in a phase configuration (where all 3 phase conductors are grouped together)and proper grounding is in place, the rf is greatly reduced.

The key to eliminating or reducing rf as far as electricians are concerned, relates to good wire connections and whenever possible, installing conductors in metal raceways with proper grounding. Beyond that, one would have to be careful as to the quality and proximity of other electrical devices.

I think if I were wiring the home, I would recommend that the home owner stay away from all ballasted devices and device that utilize transformers.

Remember, rf is a radio signal. It is more important to eliminate the unintentional antenna (metal frames on windows, copper water pipes)that may exist in the vicinity of the HAM tower and radio!

Sorry, didn't mean to blabber on!
Dave
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#83836 - 02/22/03 07:15 PM Re: RF question
Chris Rudolph Offline
Member

Registered: 05/01/01
Posts: 160
Loc: Winter Park,Fl USA
Sparky,
Most seasoned HAMS know about the causes and solutions for RFI/EMI,therefore I would seek his advice before getting started.There are many products that are used on power lines to filter unwanted interference like dimmer "hash" etc from desensitizing the receiver or distorting the transmitter .Most good receivers and transmitters have these filters already built into them.You may not have to do anything special if his equipment has the proper filtering.

Chris

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#83837 - 02/22/03 08:56 PM Re: RF question
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
Long shot, but these get spec'd for recording-studio light dimming—
http://www.superiorelectric.com/WEB_voltage/luxtrol-c.pdf

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#83838 - 02/23/03 03:55 PM Re: RF question
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
interesting Bjarney

Chris, i would venture this ham of tenure to have some filtering.

Dave,
do you suppose ballasts and x-fornmers have any sort of rf rating ?

Thinkgood,
i am unsure about isolation here. i am installing a dedicated sub panel for all ham related equipment.
initself a level of isolation.

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#83839 - 02/23/03 05:11 PM Re: RF question
WebSparky Offline
Member

Registered: 02/21/03
Posts: 144
Loc: Cleveland, Ohio
sparky;

Fluorescent ballasts:
All electronic ballasts are designed to meet FCC Part 18 for Non-Consumer Equipment, for conducted and radiated interference. Electronic ballasts may cause some interference in a home or Consumer application.
In addition electronic ballasts must be grounded to provide radio frequency filtering. This filter in all ballasts is connected to the can requiring the ballast can to be connected to a grounded fixture.

So, without good grounding.....you will pick up rf.

Assuming good grounding, all of those little transformers that come with just about everything for recharging the batteries in the device, are only two wire with no grounding to cancel out the rf.
The good thing about rf is it's limited radiation distance. Typically, unless the rf source is close to the other equipement, there is no effect.
Typically when we as electricians install power transformers, the transformers are required to be grounded thus effectively eliminating rf. These types of transformers are not required to be classified by the feds.

Hope this helps.
Dave


[This message has been edited by WebSparky (edited 02-23-2003).]
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#83840 - 02/23/03 07:51 PM Re: RF question
n1ist Offline
Member

Registered: 02/13/02
Posts: 176
Loc: Malden MA
Since lightning protection is very important, all wiring entering the shack (radio room) should pass thru a ground window - this is usually a copper plate properly grounded where appropriate lightning arrestors are mounted. Polyphaser has some very good documentation on lightning protection.

As mentioned above, watch out for light dimmers and switching ("electronic") transformers for LV lighting, both as generators of RFI and as being succeptible. Touch lights are out of the question if he operates morse code :-)

/mike

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