RCA Q36 Receiver
Restoration of Model Q36 RCA Radio
Author: Edgardo Castro Bruse
AUGUSTO EDGARDO CASTRO BRUSE
Calle Loma Linda
Residencial Loma Linda casa No. 4
Col. San Benito.
San Salvador. El Salvador.
San Salvador, April 6, 2014
This radio was a gift, given to me by my friend Dr. Fernando A. Melgar several years ago. When I received the radio it presented distorted audio, the magic eye did not work, but its shortwave reception was very good.||
Type: Broadcast Receiver
Valves/Tubes 11: 6SG7 6SA7 6SA7 6SK7 6U5 or 6G5 6SQ7 6R7 6SK7 6F6G 6F6G 5U4G
Principle Superhet with RF-stage; ZF/IF 455 kHz
Wave bands Broadcast plus more than 2 Short Wave bands.
Power type and voltage Alternating Current supply (AC) / 105-125/100-260 Volt
Loudspeaker Electro Magnetic Dynamic LS (moving-coil with field excitation coil) / Ø 8 inch = 20.3 cm
Power out: 10 W
Wooden case, tablemodel, low profile.
Dimensions (WHD) 625 x 375 x 325 mm / 24.6 x 14.8 x 12.8 inch
Notes Bands: BC, Police, 5xSW spread band.
Net weight: 22.3 kg / 49 lb
RCA Q36 schematic diagram
Repairing the Radio
The audio distortion was due mainly to two causes:
- The 6R7, a medium mu tube, had been substituted by a 6K7, a high mu tube.
- A shielded cable, disconnected from ground, automatically disconnected a resistor grounded through this cable´s shielding.
The ground connection was restored by means of a wire.
Since a 6R7 could not be found, a tube adapter was built in order to use a 6BF6 to replace the 6R7 original tube.
The "magic eye" was replaced by a new one, and to prevent a fuzzy image, the cathode pin of the 6U5 must be connected to the grounded lead of the 6U5´s filament.
Finally a complete recapping of the radio was done. Now the radio works in an excellent way!
Under Chassis of Q36 "Before" and "After" Restoration. Please click on images to enlarge
RCA Q36 before restoration
RCA Q36 chassis after restoration
6BF6 Adapter and Chassis. Please click on images to enlarge
Reassembly of Q 36 into its Cabinet
It is important to follow the sequence shown by the pictures, in order to install easily and correctly all parts into the cabinet.
Final view of restored RCA Q36