From: John De Armond
Newsgroups: alt.rv,rec.outdoors.rv-travel
Subject: Re: Hams:  RFI From Thin-Lites
Date: Tue, 30 Jan 2001 03:01:56 -0500

Dunc wrote:

> I have a 1999 Chinook RV that has several Dual Tube Thin-Lite fluorescents
> in it.
>
> I find that I get really severe RFI when they are operating.
>
> I have installed 4.7uf Tantalum Caps in them hoping to get rid of the
> oscillation, but to no avail.
>
> Any of you out there have a good solution???
> That RFI has sure ruined several good evenings of DX when camping.

You're probably pretty much out of luck with these lights and SSB.
The problem is, the lamp is lit with an inverter that runs at
anywhere from 30 to 80 khz and generates several hundred volts.
Typically a simple power blocking oscillator that generates a
waveform that looks more like a pulse train than a sine wave.
Making matters worse is the lamp(s) itself.  On each cycle, it
requires a relatively high voltage to ignite the glow discharge.
Once ignited, the tube dumps the energy stored in the transformer
core and circuit capacitance in a short, high amperage pulse.
Everything from the wiring to the lamps themselves radiate RFI.

Pretty much any solution will involve new fixtures.  Incandescent
lamps are the ultimate solution but I bet you don't want the power
hit.  A 12 volt neon transformer may help some.  The waveform tends
to be much better controlled with these.  Another alternative is to
replace the high frequency ballast with a magnetic 120 volt ballast
and then run it on an inverter.  For a number of reasons, 60 hz
operated lamps are electrically much quieter.  All ya gotta do is
find a clean inverter - probably not as difficult as it seems.

IF you knew someone who makes neon, perhaps the ultimate solution is
to have white neon (basically cold cathode fluorescent) lamps
fabricated to fit in the fixtures and drive them with 12 volt neon
transformers.  I know that this works because that's what I have on
my rig.  Doesn't bother my radios at all.  Aside from the cleaner
drivers, white neon is quiet because we use different electrode
technology and different fill pressure from fluorescent lamps.
Fluorescent lamps are designed to slowly sputter their electrodes so
that they wear out. Neon is designed NOT to sputter and to last til
you break it.  This keeps the ignition voltage down which results in
low to no EMI.

I've been known to take one of those compact fluorescent lamps that
looks like a bundle of organ tubes, cut off the hot cathode
electrodes, seal on neon electrodes, re-process the tube, put a
small neon inverter in the base and turn it on.  Not as bright as
the original CF lamp but it will last forever or until the inverter
burns out.

John