MODEL 126-B
Schematic
Socket Layout

Figure 5 - Socket Voltage Readings

IF PEAK 460 KC,

Figure 1 - Schematic Circuit Diagram

Figure 4 - Location of Line-up Capacitors

MODEL 126-13 Chassis Wiring

Figure 2 - Chassis Wiring Diagram

Model 126-B
Alignment Data
Voltage

SERVICE DATA

(1) Important
Always disconnect the batteries before attempting to remove the chassis from the cabinet. Always turn the operating switch "off" before changing tubes, batteries or fuses.

Figure 3 - Loudspeaker Wiring

(2) Line-up Capacitor Adjustments
Line-up capacitors are provided in the first detector, oscillator and intermediate amplifier to provide a means of properly aligning the receiver. A modulated R.F. oscillator, such as Full Range Test Oscillator, type TMV-97-B (Stock No. 9050), a non-metallic screw driver, such as alignment wrench (Stock No. 4160), and an output indicator are required for properly aligning this receiver. Refer to Figure 4 for the location of the line-up capacitors.

I. F. Adiustments
Two transformers comprising four circuits, two of which have trimmer capacitors, are used in the I. F. amplifier. Proceed as follows:
(a) Short-circuit the antenna and ground terminals and connect the output of the oscillator between the control grid cap of the first detector (RCA 1A6) and ground. Connect an output indicator across the voice coil leads of the loudspeaker. Place the oscillator in operation at 460 K. C. and adjust its output and

the receiver volume control until a deflection is obtained in the output indicator.
(b) Adjust the secondary and then the primary of the first I. F transformer (see Figure 4) until a maximum deflection is obtained in the output indicator.
This completes the I. F. adjustments. It is good practice to always follow the I. F. adjustments with the detector and oscillator adjustment, as there is an interlocking of adjustments that always occurs.

Detector-Oscillator Adjustments
The two0gang capacitor trimmer screws are accessible at the top of chassis. The series (600 K. C.) trimmer is accessible from the rear. Proceed as follows:
(a) Connect the oscillator between the antenna and ground terminals of the receiver. Connect the output meter across the voice coil leads of the loudspeaker.
(b) Place the oscillator in operation at 1400 K. C., set the dial at 140 and adjust the oscillator output and receiver volume control until a deflection is obtained in the output indicator.
(c) Adjust each trimmer on the gang capacitor until a maximum deflection is obtained.
(d) Set the oscillator at 600 K. C. and tune in the signal on the receiver. Then adjust the series trimmer, located on the rear of the chassis, until maximum output is obtained. While making this adjustment, rock the tuning capacitor back and forth through the signal. Then again check the adjustments in (b).

(3) Voltage Readings
The following voltages are those at the tube sockets while the receiver is in operating condition. No allowance has been made for current drawn by the meter and if low resistance meters are used, such allowances must be made.

RADIOTRON SOCKET VOLTAGES
135-Volt "B" Supply - No Signal - Maximum Volume Control

Radiotron No.
Control Grid to Ground Volts, D.C.
Screen Grid to Ground Volts, D.C.
Plate to Ground Volts, D.C.
Plate, M.A.
Filament Volts, D.C.

RCA-1A6
1st Dec.
*3.0
67.5
135
1.7
2.0

Osc.
-
-
135
1.8

RCA 34
I.F.
*3.0
67.5
135
3.0
2.0

RCA 32
2nd Dec.
*6.5
67.5
*95
0.4
2.0

RCA 30
Driver
*9.0
-
130
3.5
2.0

RCA 30
Output
12.0
-
135
1.0
2.0

RCA 30
Output
12.0
-
135
1.0
2.0

MODEL 126-B
Parts List

REPLACEMENT PARTS

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