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Re: [Amps] Topband: Elimination of Treadmill RFI on 160 meters

To: amps@contesting.com
Subject: Re: [Amps] Topband: Elimination of Treadmill RFI on 160 meters
From: Manfred Mornhinweg <manfred@ludens.cl>
Date: Wed, 28 Jan 2015 17:05:44 +0000
List-post: <amps@contesting.com">mailto:amps@contesting.com>

I would replace the bulbs with LEDs.

I second that. Being really fed up with replacing little glow bulbs, many of which are no longer available, I replace every one of them by a LED.

To replace all those small bulbs having wire leads, I use 3mm "warm white" LEDs - to be precise, eBay specials costing two dollars for a bag of one hundred. In equipment that powers the lamps from 12V, I put up to three LEDs in series, when several are needed, and add a resistor to make them run at roughly 10mA. That makes them at least as bright as the original bulbs, and the color is also very similar to that of the bulbs.

An important trick is to sand down those LEDs. As they come, they give a more or less concentrated beam of light off their fronts, unlike bulbs which give light off in all directions. In most cases LEDs give poor results if installed as they come. So I sand them down, using coarse sandpaper, creating a surface that scatters the light broadly in the desired direction. If I want omnidirectional radiation, I sand the LED body into a conical shape, instead if I want the light mostly coming out one side of the LED, I sand a flat 45 degree surface onto it. Leaving the surface very rough, by using coarse sandpaper, helps in obtaining excellent light distribution.

It works very well. I have done it to countless radios and commercial/industrial equipment, and as far as I know, none of all this equipment has ever again needed a lamp replacement.

A bonus is lower current consumption, and much lower heating, compared to bulbs.

Manfred

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