• Country
• United States of America (USA)

• Manufacturer / Brand
• Zenith Radio Corp.; Chicago, IL

• Year
• 1956/1957

• Category
• Broadcast Receiver - or past WW2 Tuner

• Radiomuseum.org ID
• 69090

• • alternative name: Chicago Radio Lab

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

• Number of Transistors
• 7

• Semiconductors
• 2N194 2N193 2N216 2N216 2N35 2N35 2N35 1N87G

• Main principle
• Superheterodyne (common); ZF/IF 455 kHz; 2 AF stage(s)

• Tuned circuits
• 5 AM circuit(s)

• Wave bands
• Broadcast only (MW).

• Power type and voltage
• Dry Batteries / AA: 4 x 1.5 Volt

• Loudspeaker
• Permanent Magnet Dynamic (PDyn) Loudspeaker (moving coil) / Ø 2.75 inch = 7 cm

• Power out
• 0.1 W (0.18 W max.)

• Material
• Plastics (no bakelite or catalin)

• from Radiomuseum.org
• Model: Royal 500 Ch= 7ZT40 - Zenith Radio Corp.; Chicago,

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

• Dimensions (WHD)
• 3.5 x 5.75 x 1.5 inch / 89 x 146 x 38 mm

• Notes

• The Zenith Royal 500 is a battery operated 7 transistor portable BC band radio. The tuning range is 540-1600kHz. The first 4 models are aluminum chassis, hand wired, point-to-point, and have 4 different chassis numbers due to limited quantities of transistors from manufacturing suppliers. The later 4 models are PCB and included vernier tuning. Chassis have chassis numbers along with a Color Code Dot in the battery compartment with labels in the same Color Code ink.

  Year	Chassis Number	Chassis Type	Transistor Source	Color Code Dot	Cabinet Colors	Vernier Tuning
  55/56	7XT40 Circuit #1	Hand Wired	Sylvania (NPN)	Black	R,Y	N
  55/56	7XT40 Circuit #2	Hand Wired	Sylvania (NPN)	Maroon	R,Y	N
  55/56	7XT40Z	Hand Wired	Raytheon (PNP)	Red	R,Y	N
  55/56	7XT40Z1	Hand Wired	Texas Instr. (NPN & PNP)	Green	R,Y	N
  56/57	7ZT40	PCB	Sylvania (NPN)	Magenta	R,W,Y	Y
  56/57	7ZT40Z1	PCB	Texas Instr. (NPN & PNP)	Brown	R,W,Y	Y
  57/58	7ZT40 "Revised"	PCB	Sylvania (NPN)	Magenta	L,R,V,W,Y	Y
  57/58	7ZT40Z	PCB	Raytheon (PNP)	Orange	L,R,V,W,Y	Y

  Color Codes:
  L = Tan/Beige (rare); R = Maroon/Burgundy/Garnet Red (semi-transparent); V = Tango Pink (rare); W = White; Y = Black/Ebony.

• Net weight (2.2 lb = 1 kg)
• 1 lb 3 oz (1.187 lb) / 0.539 kg

• Price in first year of sale
• 75.00 USD

• External source of data
• Ernst Erb

• Mentioned in
• Zenith Transistor Radios (Pages 10-14, 20, 21)

• Literature/Schematics (1)
• Transistor Radios 1954-68 (Antique Radio Magazine n.61, June-July 2004, page 53 (Ita/Eng). Free at Aldo Andreani's website.)

• Literature/Schematics (2)
• - - Manufacturers Literature (Zenith Supplementary Service Manual "Royal 500" All Transistor Portable Radio Chassis 7ZT40 7ZT40Z1)

Radio a transistor tascabili americane: Zenith Royal 500 “Owl Eyes” (Per cortesia di L.Salvatore/ARM)

3327 KB

• Documents regarding this model

• Other Models

• Here you find 4496 models, 4101 with images and 3615 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Zenith Radio Corp.; Chicago, IL