View source for 1390-B

{{GR Product
|model=1390-B
|class=generators
|summary=random noise generator
|image=GR 1390-B Front.jpg
|caption=General Radio 1390-B Random Noise Generator
|series=
|introduced=1961
|discontinued=(?)
|designers=
|manuals=
* [[Media:GR 1390-B Random Noise Generator 11_1965.pdf|General Radio 1390-B Random Noise Generator Manual 1390-0100-K (1965)]]
}}




The '''General Radio 1390-B''' is a random noise generator [[introduced in 1961]].
It first appears in [[Media:GRwiki Catalog Q OCR 1961.pdf|Catalog Q]] and remained available through Catalog78.  
The Type 1390-B provides random noise on three ranges from 20 kHz to 5 MHz.  
It produces electrical noise using a [[6D4]] gas-discharge tube, V2, operated in the field of a permanent magnet.
The noisy plate voltage of the 6D4 tube drives two stages of amplification.
Between the amplifier stages, filter networks shape the three bands.  
A voltmeter displays RMS voltage then of the noise signal before it is fed to a five position decade attenuator at the output.

==Specifications==
* '''Frequency Range:''' 5 Hz to 5 MHz in three bands.
* '''Output Voltage:''' 3 V for 20 kHz range, 2 V for 500 kHz range, and 1 V for 5 MHz range.
* '''Output Impedance:''' 900 Ω
* '''Output Attenuator:''' 1, .1, .01, .001, and .0001 times the RMS Voltmeter reading.

==Links==

* [[Media:GRwiki Exp 12_1951.pdf|Experimenter describing 1390-A December 1951]]
* [[Media:GRwiki Exp 01_1960.pdf|Experimenter describing 1390-B January 1960]]

==Photos==
<gallery>
GR 1390-B Bottom.jpg
GR 1390-B Front.jpg
GR 1390-B Left Side.jpg
GR 1390-B Rear.jpg
GR 1390-B Top A.jpg
GR 1390-B Top B.jpg
GR 1390-B V2 in magnet.jpg|Noise tube, V2, operating in magnetic field
</gallery>


[[Category:Generators]]