Wumpus´s Old Radio World. Tuning Eyes

Last update 06/05/2009. Online since 1996

Tuning indicator tubes for old-time radio sets Display image variants: Used termes for such tubes: tuning indicator tube. Tuning indicator valve. Magic Eye. Eye tube. Electron-ray indicator tube. Fan-shaped display tube. Glowing tube. And so on. Soon after introduction of the broadcasting in 1923 the industry offered support for best tuning of the receivers on the exact station frequency. First these were glowing tubes, pure optical brightness indicators, pointer measurement instruments (also shadow pointers) and light bulbs. About 1935 the vacuum tubes came as fluorescent screens on the market. First as round 'magic eyes' on the top of the bulp. (e.g., AM1,), then as fan-type side screens and at last as rectangular band screens on the side of the bulps. For a greater indication range two level types were constructed (e.g., EM4). There were also systems with not only indicator function, but also with integrated amplifiers (e.g., EFM11). Multiple displays for more complicated processes were designed (e.g., EMM803) and also, in addition tubes for switch state signal indication (e.g., EAM86, for stereo state). Here some examples:
Manufactures	Tube type Click on photos	Remarks
Telefunken	AM1	First German "magic eye". Year of construction 1937 (1936). Not used in larger quantities. The industrie offered soon the better type AM2.
Telefunken	AM2	Magic Eye
Valvo	DM 71	"Magic line, key hole indicator tube", subminature tube for battery receivers, portable tape recorders.
Valvo	EAM86	Duo display with compact rectangular screen. 2 systems, one for field strenght indication, the other for rectifying (example).
Telefunken	EFM11	Magic Eye - type. Including a pentode for r.f. and n.f. preamplifiers.
Miniwatt	EM1	Magic Eye - type.
Telefunken.	C/EM2	Magic Eye - type. for use in C-series heater circuits of AC/DC sets and for parallel heated 6.3 volts circuits of AC sets.
Valvo	EM4	Magic eye. 2 sensitivity levels
VEB Neuhaus	EM11	Magic eye, 2 sensitivity levels. GDR
Valvo	EM34	Magic eye, 2 sensitivity levels. GDR
Lorenz	EM71	Magic eye
Valvo	EM80	Fan shaped type on the the side of the glass bulb.
RFT	EM83	GDR. Interesting tube. 2 Systems for variable use. Fan shaped type. For use as a normal indicator with both systems in parallel. Using different risistors in anode line, the result was a two level indicator, one system for low level signals, the other for medium and high level signals. Also suitable for ratio indication for best FM tuning.
Lorenz	EM 85	Fan shaped type
Valvo	EM87	Rectangular screen on the the side of the glass bulb.
ITT Lorenz	EMM803	2 Systems. 2 rectangular screens on the side of the glass bulb. One for field strenght. One for yes-no-indication (e.g. r.f. stereo on/off). Last constructed tuning indicator tube.
Koerting.	GB2207GW	Glow tube, rarity. Variable light line. 1934
Valvo	PM84	Tuning indicator. For type P in series heater circuits.
Valvo	UM4	Magic eye tuning indicator tube for AC/DC power lines. For type U in series heater circuits.
Valvo	UM11	Magic eye.Tuning indicator tube for AC/DC power lines. For type U in series heater circuits. Short video clip: UM11.AVI ( 800 KB in AVI format.) Short video clip: UM11.RM (90 KB. in RM format)
Valvo	UM80	Fan shaped screen tuning indicator tube for AC/DC power lines. For type U in series heater circuits.
Mazda	6AF7	Magic eye tuning indicator tube (tuning indicator valve). (England, UK)
RCA?	6E5	Worldwide first tuning indicator tube (Magic eye) 1935 (1934). USA
Osram	8JR312B	Glow tube, rarity. Variable light line. 1934