66X3 Ch= RC-1038

RCA (RCA Victor Co. Inc.); New York (NY)

Datos
Foro
Imágenes
Colecciones

  • Año
  • 1946
  • Categoría
  • Radio - o Sintonizador pasado WW2
  • Radiomuseum.org ID
  • 53657
    • alternative name: RCA Manufacturing || Victor Talking Machine

Haga clic en la miniatura esquemática para solicitarlo como documento gratuito.

 Especificaciones técnicas

  • Numero de valvulas
  • 6
  • Principio principal
  • Superheterodino con paso previo de RF; ZF/IF 455 kHz
  • Gama de ondas
  • OM y OC
  • Tensión de funcionamiento
  • Red: Aparato AC/DC. / 105-125 Volt
  • Altavoz
  • Altavoz elíptico de imán permanente. / Ø 6 inch = 15.2 cm
  • Potencia de salida
  • 1.5 W (unknown quality)
  • Material
  • Madera
  • de Radiomuseum.org
  • Modelo: 66X3 Ch= RC-1038 - RCA RCA Victor Co. Inc.; New
  • Forma
  • Sobremesa apaisado (tamaño grande).
  • Ancho, altura, profundidad
  • 15.3 x 9.3 x 7.3 inch / 389 x 236 x 185 mm
  • Anotaciones
  • Pilot lamp: Mazda Nº 1490, 3.2V.
  • Ext. procedencia de los datos
  • Ernst Erb
  • Referencia esquema
  • Rider's Perpetual, Volume 15 = 1947 and before
  • Documentación / Esquemas (1)
  • RCA Victor Instruments Service Notes 1946

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El modelo 66X3 es parte de las colecciones de los siguientes miembros.

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Contribuciones en el Foro acerca de este modelo: RCA RCA Victor Co.: 66X3 Ch= RC-1038

Hilos: 1 | Mensajes: 7

I recently purchased an RCA 66X3 AM/SW reciever from eBay. It initially had the normal bad capacitors and several >20% out of tolerance resistors. Tubes tested OK with perhaps the RF amp (12SG7) a little weak but good. Tune up seemed to go OK, but the SW band was definitely poor with a lot of extraneous mixes on the dial that appeared to be from nearby FM stations. Sensitivity and volume was very low.

I have a battery operated o'scope and discovered that the LO seemed to be on the AVC circuits and on the circuit ground of the 12SQ7 resulting in LO on the plate of the RF amp. This situation only exists while in SW. The regular AM broadcast band is actually quite good and there is no LO on the RF amp or AVC.

I am wondering if anyone else has experienced this problem and what they did to correct it. I have had some emails with other less technical owners and they state that their sets are also weak on SW but I don't have any information on strange mixes in their sets.

Update: I found that bypassing the circuit ground of the 12SG7 (B-) to chassis did not affect the level of LO signal on the plate. LO signal on the pin 8 (signal in) of the 12AS7 (mixer) is 180° out of phase with the LO on pin 5 (osc). This must have something to do with the band switch, but contacts appear to be OK. The band switch shorts out a section of the oscillator coil to B- rather than switching in a different coil. B- comes to the bandswitch via an insulated braided cable (like the shield off of a piece of coax) and LO (12mHz) signal can be seen on the cable. Once the LO signal is coupled onto the AVC circuit, it is present on the grid of the 12SG7 (RF amp) which makes this one of those "chicken or egg" questions. 

Fred Neudecker, 02.Dec.13

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