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

[Manfred Mornhinweg]

> 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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