The FISK RADIOLETTE
MODELS 40 AND 43
Four Valve, Two Band, D.C. Operated Superheterodyne
TECHNICAL INFORMATION AND SERVICE DATA
Amalgamated Wireless Wireless Australasia)(td
THE FISK RADIOLETTE, MODELS 40 & 43 Four Valve, Two Band, D.C. Operated, Superheterodynes TECHNICAL INFORMATION
Electrical Specifications
| TUNING RANGES | Alignment Frequencies | |
|---|---|---|
| "Standard Medium Wave" | (a)200-550 metres |
"Standard Medium Wave" 1400 K.C. (214 M.)
600 K.C. |
| "Short Wave" | (b) 19.50 metres | "Short Wave"20 metres |
| Intermediate Frequency | ||
| Power Supply Rating | 190-260 Volts D.C. | Power Consumption |
| VALVE COMPLEMENT | ||
|
(1) 6A7
(2) 6D6 |
Detector-Oscillator
I.F. Amplifier |
(3) 6B7I.F. Amp., 2nd Det., A.V.C. and A.F. amp.
(4) 43Output Pentode |
|
LoudspeakerType
Loudspeaker Field Coil Res |
AE2 (R40), AJ2 (R43)
istance |
Loudspeaker TransTG54E (R40), TG116E (R43)
1000 ohms (R40), 4500 ohms (R43) |
| Replacement fuses | 3 amp. | |
| Dial Lamps |
۔
• |
|
| and the state of D 11 Jacks |
SINCE THE CIRCUIT ELEMENTS OF D.C. POWER OPERATED RECEIVERS ARE DIRECTLY CONNECTED TO THE POWER SUPPLY, GREAT CARE SHOULD BE EXER-CISED IN SERVICING THESE CHASSIS
The Radiolette 43 is the console equivalent of the Radiolette 40, and although the chassis are electrically similar, they differ slightly in mechani-cal construction. The main difference is the incorporation of the filter circuit of the Radiolette
General Circuit Description
The conventional superheterodyne type of circuit, consisting of a combined first detector-oscillator stage, an I.F. amplifier stage, a combined I.F. amplifier, second detector, A.V.C. and audio amplifier stage, and a power output stage is used.
DETECTOR-OSCILLATOR
The aerial is coupled to the control grid of the 6A7 detector-oscillator by the aerial coils T1 or T2, which are tuned by the front section of the variable condenser C5. In the 6A7 the incoming signal is combined with a locally generated oscillator signal, 460 K.C. higher in frequency, to form the I.F. or beat frequency. The frequency separation of 460 K.C. is constant throughout the entire tuning range, due to the design of the oscillator circuit components. An adjustable padding con-denser (C19) is employed on Band "A," but no adjustment is required for Band "B," where a fixed padding condenser is used. The additional bias
40 in the chassis assembly where in the Radiolet 43 it is a separate unit mounted inside the console cabinet.
Four controls operate the Radiolette; from left to right they are: Volume Control, Station Selector, Range Switch and Sensitivity Control. The power supply connection plug is attached to in the back of the Radiolette in such a way as to disconnect the power when the back is removed. This is in accordance with the wiring rules of the Standards Association of Australia
resistor R9, in the cathode circuit of the 6A7, is short-circuited by a section of the Range Switch, on Band "B." to boost the sensitivity of the Radio lette at the higher frequencies.
Two stages of I.F. amplification are used in which three transformers are employed. Excepting the secondary of the third I.F. transformer, which is untuned, the primaries and secondaries are tuned to resonance by compression type trimmer condensers. The 6D6 amplifies in the first stage and the pentode section of the 6B7 in the second. The diode plates of the 6B7 are connected and the signal is applied to them by the secondary of the third I.F. transformer for rectification across resistors R16 and R17. The rectification of the signal produces a D.C. voltage in the diode circuit proportional to the signal being received, and this is applied via filter R15 and C7 to the control grid
circuits of the 6A7 and 6D6 valves to provide automatic volume control
AUDIO AMPLIFIER.
The audio component in the diode circuit is selected by the Volume Control and fed to the control grid circuit of the 6B7, via condenser C29. for amplification. It will be noted that the pentode section of the 6B7 is employed as both an I.F. and an audio amplifier. The amplified audio signal is resistance capacity coupled to the grid circuit of the 42 output pentode. This valve amplifies the signal to a suitable level for reproduction by the loudspeaker. The transformer T8 provides the necessary matching between the output valve and the loudspeaker.
The loudspeaker fitted to the Radiolette 40 is a 6 inch electrodynamic with a field coil resistance of 1000 ohms. The field is inserted in the B+ circuit for excitation and is used for smoothing.
An 8 inch electro-dynamic loudspeaker is supplied with the Radiolette 43, and is connected to the chassis by means of a five lead cable and plug.
Alianment Procedure
Unless it is felt certain that the alignment of the Radiolette is incorrect, it is not desirable to alter the adjustments from the factory setting. However, when repairs have been made to R.F. or I.F. circuits or tampering with these circuits is suspected, complete alignment becomes necessarv.
In aligning the tuned circuits it is important to apply a definite procedure, as described below, and to use adequate and reliable test equipment. An A.W.A. Modulated Oscillator TYPE C1070 is ideal for the purpose. Visual indication of the output from the Radiolette during alignment is also necessary, any output meter of conventional design being suitable.
I.F. ALIGNMENT.
The I.F. adjustments 1, 2, 3, 4, and 5 are shown in the layout diagrams. Each circuit must be aligned to a basic frequency of 460 K.C.
To align, proceed as follows:----
- 1. Remove the grid clip from the control grid of the 6A7 and connect the output of the Modulated Oscillator, the ground connection being connected to the earth terminal of the Radiolette, that is, the terminal adjacent to the aerial terminal.
- 2. Connect an output meter in the plate circuit of the 43 ouput pentode.
- 3. Switch the Radiolette ON and allow a space of approximately one minute before making
The field coil has a resistance of 4500 ohms and is connected directly across the power supply for excitation. A filter choke T9 is included in the filter circuit of the Radiolette 43 but is omitted in the Radiolette 40 since the loudspeaker field coil serves the purpose.
HEATER VOLTAGE.
The heaters of all the valves and dial lamps are connected in series with the ballast resistor R3 across the power supply. The ballast resistor is of the correct value, when leaving the factory, to provide the heaters with their correct operating voltages when the power supply is of 230 volts or above. When it is desired to operate the Radiolette 40 on a power supply of below 230 volts. the ballast resistor should be connected as shown in fig. 5 by transferring the connecting lead to the vacant terminal on the resistor.
An adjustment is provided for the same purpose in the Radiolette 43. Resistor R3 is included in the Filter Unit, which is located in the side of the console cabinet. For a power supply of below 230 volts, the connecting link on the filter unit should be closed. See fig. 7.
adjustments to enable the valves to assume their normal operating characteristics.
- 4. Set the Station Selector pointer of the Radiolette to 550 metres on the dial scale, and turn the Volume Control to the maximum clockwise position.
- 5. Set the Modulated Oscillator to 460 K.C. and switch it ON.
- 6. Adjust the ouput meter of the Modulated Oscillator so that a slight indication is aparrent on the output meter. If a reading is not obtained, it may be that the power supply connection plug is reversed in the socket. If such is the case the Radiolette will not operate.
-
NOTE.—The output of the Modulated Oscillator should be maintained at the lowest level consistent with a good output indication. This will avoid A.V.C. action and overloading.
- 7. Beginning with adjustment No. 1 (see figs. 2 or 4) a non-metallic screwdriver is used to adjust the trimmer to a point where the maximum output reading is obtained. When the output meter reading becomes excessive. it should be reduced by adjusting the output of the Modulated Oscillator.
IMPORTANT.
The Volume Control must not be used for this ose, as inaccurate alignment will result if it is altered from the maximum clockwise position.
| Code |
Part
No. |
COILS | Code |
Part
No. |
RESISTORS | Code |
Part
No. |
CONDENSERS |
|---|---|---|---|---|---|---|---|---|
|
TI
T2 T3 T4 T5 T6 T7 T8 |
2684A
2684A 1557A 1557A 1523A 1523A 1523B 1530A TG54 |
Aerial Coil, 200-550 Metres
Aerial Coil, 19-50 Metres Osc. Coil, 200-550 Metres Osc. Coil, 19-50 Metres First I.F. Transformer 2nd I.F. Transformer Third I.F. Transformer Loudspeaker Transformer |
R16
R17 R18 R19 R20 R21 R22 |
2688
2087 |
300,000 ohms, Volume Control
300,000 ohms, 1 watt 100,000 ohms, 1 watt 300,000 ohms, 1 watt 500 ohms, 1 watt 1,500 ohms, 1 watt 100,000 ohms, 1 watt |
C16
C17 C18 C19 C20 C21 C22 C23 C24 |
2964 |
|
| RESISTORS | CONDENSERS |
C25
C26 C27 |
130 mmfd. Mica (H)
10-50 mmfd. Mica Trimmer 10-50 mmfd. Mica Trimmer |
|||||
|
RI
R2 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 |
3299 |
100,000 ohms, $ watt
100,000 ohms, $ watt 640 ohms, wire wound 1,500 ohms, $ watt 30,000 ohms, 1 watt 40,000 ohms, 1 watt 300 ohms, $ watt 20,000 ohms, $ watt 600 ohms, $ watt 600 ohms, $ watt 600 ohms, $ watt 500,000 ohms, $ watt 500,000 ohms, $ watt 2,000 ohms, $ watt 1$ Megohms, $ watt |
C1
C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 |
2964 |
500 mmfd. Mica
5-20 mmfd. Mica Trimmer 5-20 mmfd. Mica Trimmer 0.5 mfd. Paper Variable Condenser 10 mmfd. Mica (B) 0.5 mfd. Paper 1. mfd. Paper 2.5 mfd. Paper 50 mmfd. Mica (D) 0.5 mfd. Paper 130 mmfd. Mica (H) 10-50 mmfd. Mica Trimmer 10-50 mmfd. Mica Trimmer |
C29
C30 C31 C32 C33 C34 C35 C36 C37 C38 C39 C40 C41 C42 C43 |
130 mmfd. Mica (H)
.01 mfd. Paper 200 mmfd. Mica (J) 25 mfd. 25 Volt Electrolytic 200 mmfd. Mica (J) 130 mmfd. Mica (H) 10-50 mmfd. Mica Trimmer .01 mfd. Paper .01 mfd. Paper 25 mfd. 25 Volt Electrolytic .01 mfd. Paper .5 mfd. Paper .5 mfd. Paper .1 mfd. Paper .1 mfd. Paper |
Fig. I.—Circuit Diagram and Code (40).
| Code |
Part
No. |
COILS | Code |
Part
No. |
RESISTORS | Code |
Part
No. |
CONDENSERS |
|---|---|---|---|---|---|---|---|---|
|
TI
T2 T3 T4 T5 T6 T7 T8 T9 |
2684A
2684A 1557A 1557A 1523A 1523B 1530A TG116 3292B |
Aerial Coil, 200-550 Metres
Aerial Coil, 19-50 Metres Osc. Coil, 200-550 Metres Osc. Coil, 19-50 Metres First I.F. Transformer Second I.F. Transformer Third I.F. Transformer Loudspeaker Transformer Smoothing Choke |
R16
R17 R18 R19 R20 R21 R22 |
2688
3590 |
300,000 ohms, Volume Control
300,000 ohms, 1 watt 100,000 ohms, 1 watt 300,000 ohms, 1 watt 500 ohms, 1 watt 2,300 ohms, 1 watt 2,300 ohms, wire wound 100,000 ohms, 1 watt |
C18
C19 C20 C21 C22 C23 C24 C25 C26 C27 |
2964 |
10-50 mmfd. Mica Trimmer
390 mmfd. Mica Padding 5-20 mmfd. Mica Trimmer 2800 mmfd. Mica Trimmer 2800 mmfd. Mica Padding Variable Condenser .1 mfd. Paper 130 mmfd. Mica (H) 10-50 mmfd. Mica (H) 10-50 mmfd. Mica (H) .01 mfd. Paper 200 mmfd. Mica (J) 25 mfd. 25 Volt Electrolytic 200 mmfd. Mica (J) 130 mmfd. Mica (H) 10-50 mmfd. Mica (H) 10-50 mmfd. Mica Trimmer 01 mfd. Paper 700 mmfd. Paper 2.5 mfd. Paper 5.5 mfd. Paper 1 mfd. Paper 1 mfd. Paper 1 mfd. Paper |
|
R I
R2 R4 R5 R6 R7 R10 R12 R12 R13 R14 S |
2614 |
RESISTORS
100,000 ohms, 1 watt 100,000 ohms, 1 watt 640 ohms, wire wound 1,500 ohms, 1 watt 30,000 ohms, 1 watt 40,000 ohms, 1 watt 20,000 ohms, 1 watt 600 ohms, 1 watt 600 ohms, 1 watt 600 ohms, 1 watt 600 ohms, 1 watt 600 ohms, 1 watt 600 ohms, 1 watt 600 ohms, 1 watt 600 ohms, 1 watt 600 ohms, 1 watt 600 ohms, 1 watt 600 ohms, 1 watt 600 ohms, 1 watt 11 Megohms, 1 watt |
C1
C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 |
2964 |
500 mmfd. Mica
5-20 mmfd. Mica Trimmer 5-20 mmfd. Mica Trimmer .05 mfd. Paper Variable Condenser 10 mmfd. Mica (B) .05 mfd. Paper .1 mfd. Paper 2.5 mfd. Paper 50 mmfd. Mica (D) .05 mfd. Paper 130 mmfd. Mica (H) 10-50 mmfd. Mica Trimmer 130 mmfd. Mica (H) 5-20 mmfd. Mica Trimmer |
C28
C29 C30 C31 C32 C33 C34 C35 C36 C37 C38 C37 C38 C39 C40 C41 C42 C43 |
Fig. 3.—Circuit Diagram and Code (43).
Fig. 5.—Lay-out Diagram (top view), Radiolette 40.
Proceed with adjustments 2, 3, 4 and 5 in the same manner. It is advisable to repeat the adjustments in the same sequence to assure that the maximum output is obtained.
R.F. ALIGNMENT.
The R.F. adjustment screws are located beneath the tuning coils — T1 — T2, T3 — T4. They are numbered in the correct alignment order — 6, 7, 8 and 9. See figs. 2 or 4.
To align proceed as follows:----
Band "A" (200-550M).
1. Connect the output of the Modulated Oscillator to the aerial terminal marked "A," the
ground connection being connected to the earth terminal as for the I.F. alignment.
- Set the Station Selector pointer to approx. 214 metres. See that the Sensitivity Control is in the maximum clockwise position.
- 3. Set the Modulated Oscillator to 214 metres (1400 K.C.).
- 4. Tune the Radiolette to the modulated signal and adjust the output of the Modulated Oscillator so that a slight indication is produced on the output meter.
NOTE .--- The output of the Modulated Oscillator
should be maintained at the lowest level consistent with a good output indication.
- 5. Reset the Station Selector pointer to 214 metres and adjust the oscillator trimmer (No. 6) with a non-metallic screwdriver to a point where the maximum reading is obtained on the output meter.
- 6. Adjust the aerial trimmer adjustment (No. 7) to give maximum output.
- 7. Set the Modulated Oscillator to 500 metres (600 K.C.).
- 8. Tune the Radiolette to the modulated signal.
- 9. Adjust the padding condenser (C18), which is approached from the front of the chassis, with a suitable screwdriver, while tuning the Radiolette continuously through the signal. Adjust to the highest reading on the output meter.
- 10. Disconnect the Modulated Oscillator and connect an aerial and an earth wire to the Radiolette.
Tune a broadcasting station of wave-length between 450 and 500 metres. If the Radiolette is out of calibration, re-set the pointer by loosening the set screws. This will correct the calibration at the low frequency and of the scale. Repeat instructions 5 and 6 to correct the calibration at the high frequency end.
Band "B" (19-50M).
A 400 ohms non-inductive resistor should be connected between the output cable of the Modulated Oscillator and the aerial terminal, for short wave alignment, to simulate the characteristics of the average aerial.
- 1. Set the Station Selector pointer to 20 metres.
- 2. Set the Modulated Oscillator to 20 metres.
- 3. Reduce the capacitance of the oscillator trimmer (No. 8) and adjust by turning the screw in a clockwise direction, to the first "peak" reading on the output meter. Check for the image signal, which should be received at approximately 21.4 metres. It will probably be necessary to increase the output of the Modulated Oscillator for this
check. Retune the Radiolette to 20 metres and reduce the output of the Modulated Oscillator to its previous value.
- 4. Increase the capacitance of the aerial trimmer (No. 9) and adjust in an anti-clockwise direction to the first "peak" reading on the output meter while tuning the Radiolette continuously through the signal.
- NOTE.—It will be noticed on the short wave band that the oscillator and aerial trimmers have two positions at which the signal will give maximum output. While the lower capacitance is correct for the oscillator trimmer, the reverse is the case in respect to the aerial trimmer.
EARTH CONNECTION.
Two earth terminals are provided, one connected to the chassis frame and the other connected in the filter circuit. In practically all cases, quieter reception will be obtained with the earth wire connected to the latter. This terminal is located above the power fuse panel in the Radiolette 40 — see fig. 5 and on the Filter Unit in the Radiolette 43 — see fig. 7.
RESISTANCE MEASUREMENTS.
The resistance values shown have been carefully prepared so as to facilitate a rapid check of the circuit for irregularities. To obtain the full benefit from this diagram, it is advisable to consult the circuit and layout diagrams when conducting the check. Each value should hold within ± 20%. Variations greater than this limit will usually be a pointer to trouble in the circuit.
Fig. 7.—Filter Unit (Model 43).
SOCKET VOLTAGES.
| VALVE |
Cathodes
to Negative Volts |
Screen Grid
to Negative Volts |
Plate
to Negative Volts |
Plate
Current M.A. |
Heater
Volts |
|||
|---|---|---|---|---|---|---|---|---|
| 6A7 De | tector | м.₩. | 3.0 | 48 | 195 | 1.0 | 6.3 | |
| S.₩. | 1.6 | 45 | 195 | 2.4 | — | |||
| Os | cillator | 148 | 2.4 | |||||
| 6D6 I.F. | Ampli | fier M.₩ | . 2.0 | 48 | 195 | 3.7 | 6.3 | |
| 6B7 De | tector | 1.5 | 25 | 90* | 0.8 | 6.3 | ||
| 43 Per | ntode | 16.5 | 142 | 132 | 24.5 | 25.0 | ||
| Voltage across Loudspeaker field – 45 volts (Radiolette 40) | ||||||||
Voltage across Loudspeaker field — 240V. (Radiolette 43)
Measured at 240 volts D.C. supply. No signal input. Sensitivity control in maximum clockwise position.
* Cannot be measured accurately with ordinary voltmeter.
Resistance values were taken with the values removed from sockets, power supply disconnected, variable condenser in full mesh, and with the volume control and sensitivity control in the maximum clockwise position.
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