R.C.A. Victor Co., Inc. 241-B Schematic

R.C.A. Victor Co., Inc. 241-B

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Product Information:
Model:241-B
Manufacturer:R.C.A. Victor Co., Inc.

Schematics Content

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SERVICE DATA
Total "A" Battery Current... 0.48 Ampere
Average "B" Battery Current. 15 M.A.
Type and Number of Radiotrons: 2 RCA-34,1 RCA-32,5 RCA-30 - Total, 8
Tuning Range.. 540-1500 K.C.
Maximum Undistorted Output..1.0 Watt

This receiver is an eight tube battery operated Super heterodyne giving excellent performance. Features such as Clase "B" output stage, two point tone control, permanent magnet dynamic loudspeaker, local-distant switch, adapt. ability for either Air Cell or storage battery operation and the inherent sensitivity, selectivity and tone quality of the Superheterodyne are incorporated in this instrument.

Figure C - Location of Line-up Capacitor

The circuit consists of an R.F. stage using Radiotron RCA-34, a Radiotron RCA-32 as a first detector, an oscillator using Radiotron RCA-30, an I.F. using Radiotron RCA-34, and a second detector utilizing Radiotron RCA-30.
Two audio stages are used, the first using an RCA-30 and the second using two RCA-30 as a Class "B" output stage. The local distance switch is in the antenna circuit so that the antenna may be disconnected when receiving strong local stations. The volume control varies the control grid bias on the R.F. and I.F. Radiotrons. The tone control consists of a capacitor that is connected across one half of the secondary of the input audio transformer at the maximum low position. At the maximum high position this capacitor is disconnected.

Line-up Adjustments

I.F. Adjustments: Two transformers comprising three tuned circuits and one untuned circuit are used in the inter mediate amplifier. These circuits are all tuned to 175 K.C. The screws are accessible from the rear of the chassis. Pro. ceed as follows:
(a) Procure a modulated oscillator giving a signal at 175 K.C., a non-metallic screw driver, such as Stock No.
7065, and an output meter.
(b) Remove the oscillator tube and connect a ground to the chassis.
(c) Connect the oscillator output between the first detector control grid and ground. Connect thc out. put meter across the voice coil of the loudspeaker and adjust the oscillator output so that a slight deflection is obtained in the output meter
(d) Adjust the secondary of the second and then the primary and secondary of the first I.F. transformers until a maximum deflection is obtained. Go over these adjustments a second time as there is a slight interlocking of adjustments. This completes the I, F, adjustments.

R. F. and Oscillator Adjustments: The three gaog capacitor screws and 600 K.C. oscillator trimmer are acces Bible from beneath the receiver chassis. Proceed as follows:
(a) Procure a modulated oscillator giving a signal at 1400 K.C. and 600 K.C., a non-metallic screw driver, such as Stock No. 7065, and an output meter.
(b) Connect the output of the oscillator to the antenna and ground lead of the receiver. Check the dial at the extreme maximum position of the tuning capacitor. The indicator should point toward the small arrow at the edge of the dial. Then set the dial at 1400 K.C., the oscillator at 1400 K, C, and connect the output meter across the cone coil. Adjust the oscillator output so that a slight deflection is obtained.
(c) With a non-metallic screwdriver, adjust the three line-up capacitors accessible at the bottom of the receiver until maximum deflection is obtained in the output meter.
(d) Shift the oscillator frequency to 600 K.C. and tune the signal. Then adjust the 600 K, C. capacitor, until maximum deflection is obtained. The main tuning capacitor must be rocked back and forth while making this adjustment.
(e) Then realign at 1400 K.C. This completes the adjustments.

RADIOTRON SOCKET VOLTAGES
New "A" and "B" Batteries - No Signal Received - Volume Control at Maximum

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Figure 4 - Schematic Diagram

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Figure B - Wiring Diagram

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REPLACEMENT PARTS
Insist on genuine factory tested parts, which are readily identified and may be purchased from authorized dealers