[time-nuts] noise sources Re: Re. DIY atomic "resonator"

jimlux jimlux at earthlink.net
Wed Apr 12 19:04:05 EDT 2017


On 4/12/17 1:23 PM, Bob kb8tq wrote:
> Hi
>
>
> *All* incandescent lamps emit RF ….. They are a resistive device that is heated to well above
> room temperature. People do use them in simple noise figure meters. The inductance of the
> filament in a typical bulb restricts the bandwidth a bit. The are designs from at least the 1960’s
> running around. I suspect the approach is much older and that’s just when I was introduced to
> the technique (= built one).
>

The advantage of the diode noise source (a typical one is 7000K, a bit 
higher than a 3200K incandescent bulb) is that it's more stable - the 
temperature of a lightbulb filament depends on a lot of things - and 
that it can be "hotter"

A  15 dB ENR noise source is something like 9500K  - that's a lot hotter 
than something incandescent, and well above the 3700K melting point of 
tungsten




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