ORIGINAL MESSAGE:
At 08:37 PM 1/2/2006, kenw2dtc wrote:
>My elmer told me that if you put DC source in series with the neon bulb and
>a resistor and set the voltage just below the ignition voltage of the neon,
>it became a more sensitive indicator of RF. The old guys used "B"
>batteries. Today one could charge up a decent quality cap and get the same
>result.
>
>73,
>Ken W2DTC
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
That's a good idea, but remember that when a neon "fires", its
internal resistance drops. Most likely it would continue to glow even
after the RF is removed. One way around this is to put a capacitor
across the neon and a moderately large value resistor in series to
the DC source. When the neon fires it will discharge the capacitor
and the large value resistor will take some time to recharge the cap.
With the right selection of values, you will have a neon that is
quite sensitive and actually blinks in the presence of RF.
Another thing to try - haven't done it myself - is to raise the
voltage enough to fire the neon continuously, but use a large series
resistor so it is very dim (no capacitor). Putting it in an RF field
would make it glow brighter. Should be very sensitive.
Fun, huh? :-)
73, Bill W6WRT
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