• Paese
• USA (Stati Uniti d'America)

• Produttore / Marca
• Grigsby-Grunow (-Hinds) Co. (Majestic pre 1933); Chicago (IL)

• Anno
• 1932

• Categoria
• Radio (o sintonizzatore del dopoguerra WW2)

• Radiomuseum.org ID
• 43628

Clicca sulla miniatura dello schema per richiederlo come documento gratuito.

• Numero di tubi
• 11

• Valvole
• G-58-S G-56 G-58-S G-58-S G-4-S G-57-S G-57-S G-58-S G-47 G-47 G-82

• Principio generale
• Supereterodina con stadio RF; ZF/IF 175 kHz

• N. di circuiti accordati
• 7 Circuiti Mod. Amp. (AM)

• Gamme d'onda
• Solo onde medie (OM).

• Tensioni di funzionamento
• Alimentazione a corrente alternata (CA) / 117 Volt

• Altoparlante
• AP elettrodinamico (bobina mobile e bobina di eccitazione/di campo)

• Materiali
• Mobile in legno

• Radiomuseum.org
• Modello: Majestic Gothic 307 Ch= 300 - Grigsby-Grunow -Hinds Co.

• Forma
• Console, con gambe d'appoggio basse (< 50%).

• Annotazioni
• Introduced Sept. 1932. The series 300 models are fitted either with a large G-14-F speaker or have twin speaker G-19-B and G-19-C. Grigsby-Grunow uses here the first time their "Automatic Synchro-Silent Tuning", variing a tuning light by a reactor with 3 legs of iron core and suppressing signals below a certain level between stations with an additional tube. Two legs of the Reactor are connected in series with the pilot light, while the winding on the center leg is connected in series with the plates of the RF First Detector, and IF tubes. An electrolytic condenser (C-5) shunts the center winding for not getting any AC if there are unbalances. They call the system also "Reactance Resonance Indicator". When a station is tuned in, an automatic bias voltage is built across Resistor R-9, causing the pilot light to dim.
  
  Description in Rider's Majestic 3-19:
  "This is a reactor with three windings on three legs respectively of the iron core. The windings on the two end legs are connected in series with the pilot lamp, while the winding on the center leg is connected in series with the plates of the RF, 1st Detector, and IF tubes. An electrolytic condenser is connected so as to shunt the center winding. If no station is tuned in, a relatively large plate current will flow through the center winding. This saturates the iron core so that the reactance of the two outer windings is quite low, and considerable current therefore flows through the pilot light. When a station is tuned in, it operates the G-4-S Automatic Volume Control tube so that an automatic bias voltage is built up across Resistor R-9. This bias voltage is, in turn, impressed upon the control grids of the RF, 1st Detector and IF tubes. When this bias is impressed on these amplifier tubes, the normal AVC action the pilot light is therefore reduced, causing the pilot light to dim."
  
  Replacing of the unique "Spray Shield Tubes" is done by ordinary tubes plus installation of a tube shield.

• Prezzo nel primo anno
• 89.50 $

• Fonte esterna dei dati
• Ernst Erb

• Fonte dei dati
• Radio Collector`s Guide 1921-1932

• Riferimenti schemi
• Rider's Perpetual, Volume 3 = 1933 and before

• Bibliografia
• The Radio Collector's Directory and Price Guide 1921 - 1965 (Rider's Changes 7-11)

• Letteratura / Schemi (1)
• Pre-War Consoles

• Altri modelli

• In questo link sono elencati 201 modelli, di cui 122 con immagini e 156 con schemi.
  Elenco delle radio e altri apparecchi della Grigsby-Grunow (-Hinds) Co. (Majestic pre 1933); Chicago (IL)