• Country
• Netherlands

• Manufacturer / Brand
• Philips; Eindhoven (tubes international!); Miniwatt

• Year
• 1927–1935 ?

• Category
• Miscellaneous (Other, Various) - see notes

• Radiomuseum.org ID
• 211976

• Main principle
• RF Converter/Adapter (not voltage converter); something special ? Please give information (notes)

• Material
• Bakelite case

• from Radiomuseum.org
• Model: Toonzeef 4004 - Philips; Eindhoven tubes

• Dimensions (WHD)
• 30 x 15 x 40 mm / 1.2 x 0.6 x 1.6 inch

• Notes
• Low pass filter for Philips loudspeakers to reduce the sharp high tones.
  A Philips 2514 has a B443 (or PM24) output pentode that is fed with 150 volt and a current of 15 mA. The optimal load is therefore 150/0.015 = 10.000 ohm. You wonder why Philips advised loudspeakers with an impedance of 2.000 ohm for this radio, for instance the Philips 2007? The reason for this is that the impedance of loudspeakers in those days was measured at frequencies around 200 Hz. At 1000 Hz the impedance of a Philips 2007 is already over 4x times higher. This explains why Philips delivered a so-called "Toonzeef" (tone sieve) with these radios, to compensate for the fact that the yield for high tones with such a loudspeaker, connected to a B443 (or PM24), is much higher than for low tones. This problem was corrected with Philips 4004 "toonzeef" (Tone sieve). The regular value of the Philips 4004 plugs is 10 nF.
  

• Net weight (2.2 lb = 1 kg)
• 0.050 kg / 0 lb 1.8 oz (0.11 lb)

• Author
• Model page created by Rudie Dorrepaal. See "Data change" for further contributors.

• Other Models

• Here you find 5244 models, 4386 with images and 3445 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Philips; Eindhoven (tubes international!); Miniwatt