Model NS-LB Noise Generator

Brooke Clarke, N6GCE 2002 - 2023

A.R.I. NS-LB Noise Gen


This Noise Model NS-LB generator was made by Aerospace Research, Inc. of Boston, MA.  It uses a 5722 Noise diode tube with a Tungsten filament using the "shot effect" (Wiki).  There is a solid state control circuit that varies both the DC filament current and the plate voltage in order to produce a variable excess noise.

The filament voltage needs to be varied from 2.0 to 5.5 Volts while the plate voltage varies from 10 to 200 Volts.  The tube is specified up to about 500 MHz, but the construction of this noise generator may go higher. 
NF (Noise Factor) = 20 * I * R
NFdb = 10 * LOG10 (20 * I * R)

where: I = Plate current in Amps, R = generator resistance, 50 Ohms in this case.

Type-N male output.


Manual or schematic: Let me know.

HP 343A VHF Noise Source

I think the HP VHF source uses the same 5722 noise tube.  It's specified as 5.2 dB Excess Noise Ratio (ENR) and 3.1 ma.
Maybe 3.3 ma would be closer to 5.2 dB ENR.


This is a very similar noise source where the filament current is the adjustment that controls the noise output.
According to MIL-HDBK-172A Vol 1: The SG-8 superceeds the TS-195/GP.
Frequency range: 10 to 150 Mc
NF Range: 0 to 30 (50 Ohms)
TO 16-35SG8-2
TO 16-35SG8-3
TO 16-35SG8-4
USAF Spec 7524

GR 1390

This noise generator uses a tube acting as a diode to generate noise then uses filters and amplifiers to control the noise bandwidth and level, so is NOT at all similar.
GR 1390 Random Noise Generator Manual -

Y-Factor Noise Measurement

See: Microwave Test Equipment/Noise Figure


Cryptography makes use of various types of random number generators (Wiki) and  pseudorandom number generators (Wiki).  The former make use of devices like the above physical noise generators or radioactive decay while the latter make use of number computation.


Radio Museum - 5722 Tube
Sylvania Technical Manual 1949
- 5722_gif1 - 5722-gif2  -  5722_gif3
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page created 13 June 2002.