Hi Back in the day (1960’s) noise diodes were quite a bit more expensive than they are today. Even today, a miniature lightbulb is quite a bit less expensive than a noise diode. You don’t go that way because it’s better. You go that way because it’s cheap ….
Bob > On Apr 12, 2017, at 7:04 PM, jimlux <[email protected]> wrote: > > 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 > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
