• Country
• Great Britain (UK)

• Manufacturer / Brand
• Homebrew - ORIGINAL; GB

• Year
• 1964

• Category
• Service- or Lab Equipment

• Radiomuseum.org ID
• 304501

Click on the schematic thumbnail to request the schematic as a free document.

• Number of Tubes
• 1

• Valves / Tubes
• A2087 85A2

• Number of Transistors
• 2

• Semiconductors

• Wave bands
• Short Wave (SW only)

• Power type and voltage
• Powered by external power supply or a main unit. / 6 & 180 Volt

• Loudspeaker
• - - No sound reproduction output.

• Material
• Metal case, TUBES VISIBLE

• from Radiomuseum.org
• Model: High level RF noise generator - Homebrew - ORIGINAL; GB

• Shape
• Very small Portable or Pocket-Set (Handheld) < 8 inch.

• Dimensions (WHD)
• 93 x 120 x 120 mm / 3.7 x 4.7 x 4.7 inch

• Notes

• Home built by GM3NZI in 1964.

  A thermionic noise generator diode operating with saturated anode current provides a known absolute RF noise level over a broad band of frequencies. However, with a 50 or 75 ohm load the valve life at the anode currents required for high output noise levels results in short valve life. (e.g., only 100 hours at 20 mA for the A2087).

  This noise generator was designed to supply a constant high noise output level to a low impedance load for long-term stability measurements of a special receiver, but only over a limited frequency band around 30 MHz. It employs a tuned impedance transformer to allow the diode to deliver a high noise level to the load, while operating at a current (typically 4 mA) that permits a valve life of over 1000 hours. Because of the impedance transformer the output level is not absolute, so the device isn't suitable for receiver noise factor measurements (which don't require a high noise level anyway).

  The nominal 6v filament supply should be in the range 5.7 - 7.0v, floating wrt earth. The 180v supply may be negative earthed. A jack socket is provided to allow a chart recorder to be used to monitor the saturated anode current, which is stabilised by the Darlington pair in the filament circuit.

  Built in an Eddystone die cast box.

• Net weight (2.2 lb = 1 kg)
• 0.7 kg / 1 lb 8.7 oz (1.542 lb)

• Author
• Model page created by Bruce Taylor. See "Data change" for further contributors.

• Other Models

• Here you find 41 models, 19 with images and 7 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Homebrew - ORIGINAL; GB