Message-ID: <000701c4940f$17835600$0a03210a@Hugh>
From: "Hugh M0WYE" <m0wye@thersgb.net>
To: rsgb_lf_group@blacksheep.org
References: <EPECIMHCBLPKNKKFIKKOOEAHDNAA.f6agr@wanadoo.fr> <001001c49402$4eb5cfc0$edce28c3@erica> <009601c49405$e78029a0$08540150@captbrian>
Date: Mon, 6 Sep 2004 13:38:19 +0100
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Subject: LF: Re: Save energy, but generate QRM ...
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Low Energy Light Bulbs
Hi All,
All the electronic ones have some kind of oscillator in them. There is no 
screening, and there is little space for filter components, so the fact is 
most of them radiate somewhere. (or cause the house wireing to radiate)
The circuit is often just a two transitor power oscillator running off 
rectified mains,and driving a small transformer. Although some of them have 
a couple of small ICs in them.
Similar circuit in the 12V lighting transformer. The crudely rectified mains 
amplitude modulates the oscilator frequency producing a wide spread. The 
"comb" of frequencies drifts with the oscilator temperature.

There is another type which use a conventional Ballast and Glow-switch 
starter, but they seem to be going out of fashion. Because these operate at 
50Hz, they are no more obnoxious than a conventional fluorescent tube.

EMC testing is usually for radiated emmissions above 30MHz, and for 
conducted emmisions below 30MHz.

I have a 12V 8W "Caravan Light", which I use when I operate /P after dark. 
It was exceptionally dirty, but I found that by adding some local 
decoupling, grounding the metalwork of the lamp, and putting a ferrite ring 
on the cable, (all the usual EMC fixes) the interferance was reduced 
considerably.

73
Hugh M0WYE


----- Original Message ----- 
From: "captbrian" <captbrian@ukonline.co.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: Monday, September 06, 2004 12:37 PM
Subject: LF: Re: Re: Save energy, but generate QRM ...


> The fact is that some do and some do not cause HF interference. I have not
> checked every one at LF. . I have several that are satisfactory and two 
> that
> are not. The problem is not with one's own house, where baddies can be
> switched off,but with 'them' next door.
>
> G3GVB
> ----- Original Message -----
> From: g3ldo <g3ldo@ukonline.co.uk>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Monday, September 06, 2004 12:11 PM
> Subject: LF: Re: Save energy, but generate QRM ...
>
>
>> Jean-Louis F6AGR said:
>>
>> > Let me introduce to you a new candidate to the "Ugliest 137 kHz QRM
>> > generator Challenge".
>> > I'm talking about the Philips SL.E Pro 16W Warm White light bulb.
>> > This light bulb (quite expensive) saves energy and uses only 16 watts 
>> > AC
>> to
>> > produce the same light as a 100 watts conventional light bulb, but
>> generates
>> > an horrible noise (multiple discrete frequency lines) all over the 137
> kHz
>> > band.
>>
>> About three years ago I tentitively tried out one of these energy saving
>> bulbs and didn't find any interference throughout the LF/HF spectrum and
>> have, over a period introduced more into the house. These bulbs do save a
>> lot of energy, which is a consideration with cost of energy in this
> country.
>> So perhaps we could draw up a list of low energy bulbs that don't cause
>> interference.
>>
>> Most of the bulbs I have are cheap ones from Woolworths and are described
> as
>> BIAX V257 made by GE Lighting.
>>
>> As regards electronic 'transformers' could the fix be just to replace it
>> with a conventional transformer?
>>
>> Peter, G3LDO
>>
>>
>>
>
>
>