• Country
• United States of America (USA)

• Manufacturer / Brand
• McMurdo Silver Co., Inc.(post WW2); Hartford

• Year
• 1947

• Category
• Service- or Lab Equipment

• Radiomuseum.org ID
• 222671

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

• Number of Tubes
• 5

• Valves / Tubes
• 6C4 6C4 6AK6 6E5 5Y3GT

• Number of Transistors

• Semiconductors
• 1N34

• Wave bands
• - without

• Power type and voltage
• Alternating Current supply (AC) / 105-125 Volt

• Loudspeaker
• Permanent Magnet Dynamic (PDyn) Loudspeaker (moving coil) / Ø 3.5 inch = 8.9 cm

• Material
• Metal case

• from Radiomuseum.org
• Model: Signal Tracer "SPARX" 905 - McMurdo Silver Co., Inc.post

• Shape
• Tablemodel, low profile (big size).

• Dimensions (WHD)
• 12.375 x 7.375 x 5.125 inch / 314 x 187 x 130 mm

• Notes

• The original McMurdo Signal Tracer "SPARX" 905 has an R-C circuit in the 1N34 crystal RF probe (see sch1 & sch1_probe1). Shortly after the initial production run, there were issues with this probe, so an "Improved Model" was designed with the RF probe's R-C circuit eliminated, along with some minor circuit changes in the chassis (see sch2 & sch2_probe2).

  All 905's manufactured after March 1, 1947, were the "Improved Model" and an "Improved Model" was stamped on the rear. Details are described in Radio News, Oct. 1946, and Radio Service Dealer, April 1947.

• Net weight (2.2 lb = 1 kg)
• 9 lb 6 oz (9.375 lb) / 4.256 kg

• Price in first year of sale
• 39.90 USD

• Source of data
• Radio Retailing (Radio & Television R.)

• Literature/Schematics (1)
• Radio News (Oct. 1946, pages 36-37, 149-152.)

• Literature/Schematics (2)
• Radio Service Dealer, April 1947, pages 25-27, 40.

• Author
• Model page created by Heiko zur Mühlen. See "Data change" for further contributors.

• Other Models

• Here you find 16 models, 9 with images and 9 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from McMurdo Silver Co., Inc.(post WW2); Hartford