• Country
• Japan

• Manufacturer / Brand
• Meguro Electronics Corporation; Tokyo

• Year
• 1975

• Category
• Service- or Lab Equipment

• Radiomuseum.org ID
• 309429

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

• Number of Tubes
• 1

• Valves / Tubes
• 130ARB1

• Number of Transistors
• Semiconductors present.

• Semiconductors

• Main principle
• Superheterodyne (common); ZF/IF 455/10700 kHz

• Wave bands
• Wave Bands given in the notes.

• Power type and voltage
• Alternating Current supply (AC) / 220 Volt

• Loudspeaker
• - - No sound reproduction output.

• Material
• Metal case

• from Radiomuseum.org
• Model: AM-FM Radio IF Genescope MSW-721D - Meguro Electronics Corporation

• Dimensions (WHD)
• 220 x 345 x 460 mm / 8.7 x 13.6 x 18.1 inch

• Notes

• This is essentially a 'Wobulator' for 455 KHz and 10.7 MHz IF alignment.

  Band A uses outer controls for 455 KHz centre frequency. It can sweep 400 KHz to 500 KHz approximately.

  Marker Frequencies Band A: 445, 455, 465 KHz.

  Crystal reference is 555kHz and thus the Hartley VCO is centred at 100 KHz.

  Band B uses inter controls for 10.7 MHz centre frequency. It can sweep 9.5Mhz to 11.5 MHz approximately.

  Marker Frequencies Band B: 10.55, 10.70, 10.85 MHz.

  Crystal reference is 12.05 MHz and thus the Hartley VCO is centred at 1.35 MHz.

  Operation

  The crystal oscillator for band A or B is mixed with the VCO. The VCO is used for both bands via coil switching. The output is fed to a gain control and attenuator to drive the radio under test.

  The markers are not output. They are LC oscillators at the actual frequency. A mixer with filters is used to add them to the input channel, beating against the main up-converted output. The input channel (Y-axis) has a 20 dB attenuator option and a calibration reference. It's assumed the input is connected to the AM detector or FM discriminator, otherwise a user supplied peak detector can be used.

  Input sensitivity: 10 mV per cm, or more. 20dB attenuator switch.

  The sweep sawtooth is generated from one 1/2 cycle of the AC mains, so is 30 Hz or 25 Hz. the other half of the time period is blanking. The drive to the VCO varicap can be reduced to zero sweep.

  The MSW-710D is mentioned in the manual (455KHz only) as is the MSW-720D (10.7MHz), they simply omit markers, band switch and a crystal oscillator, if they actually existed. The MSW721E is similar but with IEC mains socket, switched supply voltages and more markers on each band, possibly 5. The MSW721D was ordered as 100, 115, 220 or 230 according to the manual. The 220V is the standard version.

• Net weight (2.2 lb = 1 kg)
• 14 kg / 30 lb 13.4 oz (30.837 lb)

• Author
• Model page created by Michael Watterson. See "Data change" for further contributors.

• Other Models

• Here you find 12 models, 12 with images and 4 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Meguro Electronics Corporation; Tokyo