SERVICE DATA

Voltage Rating... 100-125 Volts and 200-250 Volts

Frequency Rating 25-60 (100-125 Volt Only) and 50-60 Cycles

Power Consumption.. 110 Watts

Type and Number of Radiotrons ... 3 RCA-58,1 RCA-2A7, 1 RCA-2B7, 1 RCA-56,1 RCA-53,1 RCA-80 - Total 8

Type of Circuit - Straight Super - Heterodyne for all frequencies with Class "B" Output Stagc.

Undistorted Output... 6 Watts

This all wave super-heterodyne receiver is of the con. tinuous tuning type utilizing a straight super-heterodyne circuit in all bands. The bands are as followe:

Figure D - Location of nuts and lockwashers holding coil assembly

This receiver will be supplied in two models, one including all bands and one with band X omitted. These instructions, however, will cover both types of the receiver. The variations in the wiring for the two models are plainly shown in the illustrations. Figures A, B and C show the schematic circuit and wiring diagrams.
The circuit consists of an R.F. stage using Radiotron RCA-58, a combined oscillator and first detector using Radiotron RCA-2A7, an I.F. stage using RCA-58, a second detector and A.V. C. using RCA-2B7, an A.F. driver using RCA-56, and a Class " B * output stage using an RCA-53. The RCA-80 functions as the rectifier in the power supply circuits.
The foregoing Radiotrons and circuit functions apply to bands X, A, B and C only. In the case of band D, an additional R.F. stage utilizing an additional Radiotron RCA-58 is used. This is to increase the sensitivity and image frequency selectivity and to reduce the interference caused by tube biss and 445 K.C. signals or static.
The intermediate frequency is 445 K.C. The use of this frequency gives an especially good image frequency ratio and makes easier alignment of the'oscillator at the higher frequency bands.

Mechanical Construction
The chassis consists of two major assemblies, which must be disassembled for certain repair work. These assemblies con. sist of the chassis proper, including the main frame, power transformer, etc., and the coil assembly. The coil assembly consists of fifteen transformers supported upon individual tubular bakelite forms, each fastened to a separate porcelain strip upon which the coil terminals are mounted with their associate trimmer capacitor. This entire assembly with the selector switch is grouped in a shielded compartment which is mounted in the base of the main chassis assembly.
In order to remove this assembly it is necessary to remove the four nuts shown in Figure D and unsolder the connections of the fifteen leads shown in Figure C at the points where they connect to the main chassis. The leads should be allowed to remain on the coil assembly. After this is done, the coil assembly may be removed and repairs to it or to the main chassis may be easily made. If a coil or its associated trimmer is to be replaced, then only the bottom shield of the coil assembly must be removed. This is done by removing the four puts that hold it to the chassis studs. This is shown in Figure D.

Line - Up Capacitor Adjustments
This receiver is aligned in a similar manner to that of a standard broadcast band receiver. That is, the three main tuning capacitors are aligned by means of three trimmers in each band and on the three lowest frequency bands a series trimmer is adjusted for aligning the oscillator circuit. The other two bande do not require this low frequency trimmer, it being fixed in value. In the case of band D, it is necessary to adjust four trimmers due to the additional R.F. stage used.

Electrical Specifications
Voltage Rating... 100-125 Volts and 200-250 Volts
Frequency Rating 25-60 (100-125 Volts Only) and 50-60 Cycles Power Consumption..
Power Consumption .. 110 Watts
Type and Number of Radiotrons
3 RCA-58
1 RCA-2A7
1 RCA-2B7
1 RCA-56
1 RCA-53
1 RCA-80
Total, 8
Type of Circuit Straight Super - Heterodyne for all frequencies with Class "B" Output Stage.
Undistorted Output. 6 Watts

This all-wave super-heterodyne receiver is of the continuous tuning type, utilizing a straight super-heterodyne circuit in all bands. The bands are as follows:

This receiver will be supplied in two modele, one including all bands and one with band X omitted. These instructions, however, will cover both types of the receiver. The variations in the wiring for the two models are plainly shown in the illustrations. Figures A, B and C show the schematic circuit and wiring diagrams.

The circuit consists of an R.F. stage using Radiotron RCA-58, a combined oscillator and first detector using Radiotron RCA 2A7, an I.F. stage using RCA-58, a second detector and A.V. C. using RCA-2B7, an A.F. driver using RCA-56, and a Class " B output stage using an RCA-53. The RCA-80 functions as the rectifier in the power supply circuits.

The foregoing tubes and circuit functions apply to bands X, A, B and C only. In the case of band D, an additional R.F. stage utilizing an additional Radiotron RCA-58 is used. This is to increase the sensitivity and image frequency selectivity and to reduce the interference caused by tube hiss and signals corresponding to the intermediate frequency,

The intermediate frequency is 445 K.C. The use of this frequency gives an especially good image frequency ratio and facilitates alignment of the oscillator at the higher frequency bands.

Mechanical Construction
The chassis consists of two major assemblies, which must be disassembled for certain repair work. These assemblies consist of the chassis proper, including the main frame, power transformer, etc., and the coil assembly. The coil assembly consists of fifteen transformers supported upon individual tubular bakelite forms, each fastened to a separate porcelain strip upon which the coil terminals are mounted with their associate trimmer capacitor. This entire assembly, with the selector switch, is grouped in a shielded compartment which is mounted in the base of the main chassis assembly.

In order to remove this assembly it is necessary to remove the four nuts shown in Figure D and unsolder the connections of the fifteen leads shown in Figure C at the points where they connect to the main chassis. The leads should be allowed to remain on the coil assembly. After this is done, the coil Assembly may be removed and repairs to it or to the main chassis may be easily made. If a coil or its associated trimmer is to be replaced, then only the bottom shield of the coil assembly must be removed. This is done by removing the four nuts that hold it to the chassis studs. This is shown in Figure D.

Line - Up Capacitor Adjustments
This receiver is aligned in a similar manner to that of a standard broadcast band receiver. That is, the three main tuning capacitors are aligned by means of three trimmers in each hand and, on the three lowest frequency bands, a series trimmer is adjusted for aligning the oscillator circuit. The other two bands do not require this low-frequency trimmer, it being fixed in value. In the case of band D, it is necessary to adjust four trimmers, due to the additional F.R. stage used.

The intermediate frequency amplifier is aligned in a similar manner to that of standard broadcast receivers except that it is aligned at 445 K.C. In order to properly align the receiver, it is essential that the Stock No. 9050 Test Oscillator be used. This oscillator covers the frequencies of 90 K.C. to 25,000 K, C., continuously, has good stability and includes an attenuator. In addition to the oscillator, a 300 ohm resistor, for use as a "dummy" antenna, a non-metallic screw-driver Buch as Stock No. 4160, and an output meter are required. The output meter should be preferably a thermocouple galvanometer connected either across or in place of the cone coil of the loudspeaker.
To align the intermediate frequency circuits, connect the output of the external oscillator to the grid of the first de. tector. For the R.F. and oscillator adjustments, the oscillator output should be connected to the antenna and ground terminals of the receiver with a 300 - ohm resistor inserted in series with the antenna lead. In many cases, however, the Bignal strength obtained with this direct connection will be too great to permit proper alignment, even at the minimum Betting of the oscillator attenuator, When this is true, the external oscillator must be loose-coupled to the receiver. This is done by connecting the 300 - ohm resistor between the antenna and ground terminals of the receiver and attaching a short length of wire to the antenna post. Lay the free end of this wire across the oscillator case, adjusting its position as necessary to obtain the degree of pickup required,
The output of the external oscillator should be at the minimum value necessary to obtain a deflection in the output meter when the volume control is at its maximum position. All adjustments are made for a maximum deflection in the output meter.

The accuracy of line-up of each band may be checked without touching the trimmer condensers, by the use of the tuning wand, Stock No. 6679.
One end of the wand consists of a brass cylinder. When this is inserted in a coil the effective inductance of the coil is lowered.
The other end of the wand contains a special finely divided iron suitable for use at radio frequencies. When this is in. berted in a coil the inductance is raised.

To use the tuning wand a signal is first tuned in at the frequency at which a check is desired on alignment. The wand is then inserted slowly in the Antenna and R.F. trang. formers, using first one end and then the other end of the wand. Unless the alignment is perfect, it will be found that the power output indicated by the meter will be increased to a peak for a critical position of the wand in the coils.
The end of the wand required indicates whether the coil is high or low.

Power Supply - The instruments in this series are supplied in either of two alternating current power supply ratings: (1) 100-125 / 200-250 volts, 50-60 cycles and (2) 100-125 volts, 25-60 cycles (see rating label inside cabinet). To insure correct radiotron operating voltages, both types are equipped to permit rearrangement of the internal connections to conform with the actual voltage available. Thus, the 5060 cycle models may be adapted for 100-115, 115-125, 200-230 or 230-250 volts; and the 2560 cycle models for either 100-115 or 115125 volts.

Of course, alignment correction at the high-frequency end of a tuning range should be accomplished by the use of the trimmer condenser. If a ligament correction should be required at the low-frequency end of a tuning range, it may be accomplished by sliding the end coil of the transformer. The winding farthest from the trimmer panel is pushed toward the trimmer panel to increase the inductance, and farther away to decrease the inductance. On band D coils, the last two or three turns may be pushed in a similar manner to obtain the proper inductance.

This adjustment should not be attempted unless a quite appreciable improvement will result (as shown by the tuning wand).
The following chart gives the details of all line-up adjustments. The receiver should be lined up in the order of the adjustments given on the chart. Refer to Figure E for the location of the line-up capacitors.

Pickup Connections
A terminal board is provided at the rear of the chassis for attaching a magnetic pickup to this instrument. Such connections are shown in Figures F, G and H.

Transformer Connections
The power transformer of the 50-60 cycle receiver uses two tapped primary windings. By connecting them in parallel or in series, the receiver may be used either on 110 or 220 volt lines. Figure J shows the proper manner of making the various connections possible for this transformer.
The 25-60 cycle transformer uses only one 100125.volt winding, a tap being provided for the lower voltages. Nor. mally the transformer is connected for 115-125 - volt lines, but the connection shown in Figure I may be used for 100-115 - volt lines.

TUBE SOCKET VOLTAGES
120 Volt A.C. Line

The intermediate frequency amplifier is aligned in a similar manner to that of standard broadcast receivers except that it is aligned at 445K.C. In order to properly align the receiver, it is essential that the Stock No. 9050 Test Oscillator be used. This oscillator covers the frequencies of 150 K.C. to 20,000 K, C. continuously, bas good stability and includes an attenuator. In addition to the Oscillator, a non-metallic screw. driver buch as Stock No. 7065, and an output meter are required.
The output meter should be preferably a thermocouple galvanometer connected either across or in place of the cone coil of the loudspeaker.
The output of the external oscillator should be at the minimum value necessary to obtain a deflection in the output meter when the volume control is at its maximum position.

Figure E - Location of line-up capacitors.

The external oscillator output should be connected between antenna and ground for the R.F. and oscillator adjustments and between the first detector grid and ground for the I.F. adjustments. All adjustments are made for a maximum deflection in the output meter.
The accuracy of line-up of each band may be checked with. out touching the trimmer condensers, by the use of the tun. ing wand, Stock No. 6679.
One end of the wand consists of a brass cylinder. When this is inserted in a coil the effective inductance of the coil is lowered.

The other end of the wand contains a special finely divided iron suitable for use at radio frequencies. When this is inserted in a coil the inductance ie raised.
To use the tuning wand a signal is first tuned in at the frequency at which a check is desired on a ligament. Tho wand is then inserted slowly in the Antenna and R.F. trans. formers, using first one end and then the other end of the wand. Unless the alignment is perfect, it will be found that the power output indicated by the meter will be increased to a peak for a critical position of the wand in the coils.
The end of the wand required indicates whether the coil is high or low.
Of course, alignment correction at the high frequency end of a tuning range should be accomplished by the use of the trimmer condenser. If alignment correction should be required at the low frequency end of a tubing range it may be accomplished by sliding the end coil of the transformer. The wind. ing farthest from the trimmer panel is pushed toward the trimmer panel to increase the inductance, and farther away to decrease the inductance. Op band D coils, the last two or three turns may be pushed in a similar manner to obtain the proper inductance.
This adjustment should not be attempted unless a quite appreciable improvement will result (as shown by the tuning wand).
The following chart gives the details of all line-up adjustments. The receiver should be lined up in the order of the adjustments given on the chart. Refer to Figure E for the location of the line-up capacitors.

Pickup Connections
A terminal board is provided at the rear of the chassis for attaching a magnetic pickup to this instrument. Such connections are shown in Figures F, G and H.

Transformer Connections
The power transformer of the 50-60 cycle receiver uscs two tapped primary windings. By connecting them in parallel or in series, the receiver may be used either on 110 or 220 volt lines. Figure J shows the proper manner of making the various connections possible for this transformer.
The 25-60 cycle transformer uses only one 100-125 - volt winding, a tap being provided for the lower voltages. Normally the transformer is connected for 115-125 volt lines but the connection shown in Figure I may be used for 100-115 volt lines.

Figure A Schematic Circuit Diagram

IF PEAK 445 KC.

Figure A - Schematic Circuit Diugram

Figure E - Location of line-up capacitors

Figure D - Location of nuts and lockwashers holding coil assembly

Figure B - Chassis Wiring

Figure B - Wiring Diagram of Chassis Assembly

Figure C - Wiring Diagram of Coil Assembly

Figure C - Wiring Diagram of Coil Assembly

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

Figure F - Typical Pickup Connections

Figure G - Table Phonograph Connections

Figure H - End Table Connections

Figure I - 100-115 Volt Connection of 25-60 Cycles Transformer

Figure J - Power Transformer Connections (50-60 cycles)

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