Silvertone 5008 Ch= 132.83601 Order=57A 5008

Sears, Roebuck & Co.; Chicago (IL)

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  • Année
  • 1964/1965 ?
  • Catégorie
  • Radio - ou tuner d'après la guerre 1939-45
  • Radiomuseum.org ID
  • 93316
    • Brand: Silvertone

Cliquez sur la vignette du schéma pour le demander en tant que document gratuit.

 Spécifications techniques

  • No. de tubes
  • 6
  • Principe général
  • Super hétérodyne avec étage HF; FI/IF 455 kHz; 2 Etage(s) BF
  • Circuits accordés
  • 7 Circuits MA (AM)
  • Gammes d'ondes
  • PO uniquement
  • Tension / type courant
  • Appareil tous courants (CA / CC) / 117 Volt
  • Haut-parleur
  • HP dynamique à aimant permanent + bobine mobile / Ø 5 inch = 12.7 cm
  • Matière
  • Plastique moderne (pas de bakélite, ni de catalin)
  • De Radiomuseum.org
  • Modèle: Silvertone 5008 Ch= 132.83601 Order=57A 5008 - Sears, Roebuck & Co.; Chicago
  • Forme
  • Modèle de table sans poussoirs, modèle cheminée
  • Dimensions (LHP)
  • 15 x 6 x 5 inch / 381 x 152 x 127 mm
  • Remarques

  • 12BA6 RF preamp is tuned at the input and output with a 3 gang tuning capacitor. Unusual Hum bucking 12k resistor from Bplus to 35C5 120R cathode resistor.

    Char brown/ivory cabinet. Same model in Light gray-green/ivory: model 5009.

  • Source du schéma
  • Beitman Radio Diagrams Vol. 25, 1965
  • Auteur
  • Modèle crée par Egon Penker. Voir les propositions de modification pour les contributeurs supplémentaires.

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Contributions du forum pour ce modèle: Sears, Roebuck & Co.: Silvertone 5008 Ch= 132.83601 Order=57A 5008

Discussions: 1 | Publications: 2

Fellow Radiophiles,

I came across this above-average 6 tube AC/DC set at ebay auction 260391674867 by seller collect-m-all.

 

 

 

This set has an unsual 12k resistor from Bplus to the 120R resistor at the cathode of the 35C5 tube. This resistor couples an ammount of hum into the cathode that cancels the hum presented by Bplus at the plate via the output transformer.

This is yet another hum-bucking scheme that makes use of limited bypass capacitance to achieve very low hum output. I made a recent post about about hum bucking. A search for "Brumm" or "Brummkompensation"  will yield several hits in the German forum, which I have read with Google-translate.

Note the three section Electrolytic filter capacitor with 330 Ohm resistors for high order filtering. This is also an extra hum reducing measure.

 

 

 

This set also has an unusual RF transformer loading the 12BA6 RF preamp. The primary is fixed-tuned with a 100pF capacitor, and is (over-?)coupled to the secondary with a 2.2pF capacitor, which is tuned.

The primary must have a Q not much greater than 2 if it is to cover the AM band. Perhaps the operation of this transformer is somewhat similar to antenna coupling transformers found in sets with a wire antenna connection, except that the antenna transformer primaries usally have a loosely coupled untunned high impedance.

 

 

Any further insight on the RF output transformer would be appreciated.

Regards,

-Joe

Joe Sousa, 21.Jan.10

Weitere Posts (2) zu diesem Thema.