AWA 52, 163 Diagram

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The FISK

RADIOLA

MODELS 52 and 163

Five Valve, Two Band, A.C. Operated Superheterodynes

TECHNICAL INFORMATION AND SERVICE DATA

Shaw Stratter

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THE FISK RADIOLA, MODELS 52 and 163

Five Valve, Two Band, A.C. Operated, Superheterodynes

TECHNICAL INFORMATION

Electrical Specifications

TUNING RANGES		Alignment Frequencies
"Standard Medium Wave"	"A" 1500-500 K.C.	"Standard Medium Wave" 1400 K.C. 600 K.C.
"Short Wave"	"B" 16-50 metres	"Short Wave" 18 metres
Intermediate Frequency
Power Supply Rating	200-260V., 50-60C.	Power Consumption 50 watts
VALVE COMPLEMENT
(1) 6A7	Detector-oscillator	(3) 6B7 I.F. Amp., 2nd det. A.V.C. and A.F. Amp,
(2) 6D6	I.F. Amplifier	(4) 42 Output Pentode
	(5) 80	Rectifier
	6U5 or 6G5 Visua	l Tuning Indicator
Dial Lamps	•	6.3 volts, 25 amp.
Loudspeaker	AE5 (Mantel)
Loudspeaker Transformer	TG52E (Mantel)

Loudspeaker Field Coil Resistance ...... 1600 ohms

General Description

The chassis used in the Mantel and Console models are similar and differ, mainly, only in the method of mounting the loudspeaker and the type employed.

In the Mantel model, the loudspeaker is mounted on the chassis and, in the case of the Console, in the lower compartment of the cabinet and connected by a four lead cable and plug.

Visual tuning is provided in the Console only, a 6U5 or 6G5 Visual Tuning Indicator being employed.

Alignment Procedure

Unless it is felt certain that the alignment is incorrect it is not desirable to alter the adjustment from the factory setting. Alignment is necessary, however, if the adjustments have been altered from the original setting or repairs have been effected to any of the tuned circuits.

In aligning the tuned circuits it is important to apply a definite procedure, as tabulated below, and to use adequate and reliable test equipment.

Features of these receivers include the following:

Air trimmers and inductance tuning ensures permanent alignment of efficiently and delicately tuned R.F. and I.F. circuits; fixed condensers and inductances specially impregnated against moisture, thus ensuring sustained efficient performance under all climatic conditions; automatic volume control; continuously variable tone control; straight line frequency tuning condenser allowing a greater number and more even spacing of call signs; chassis of high grade steel, heavily plated with cadmium to resist corrosion and suspended on rubber mountings.

An A.W.A. Modulated oscillator, Type C1070, in conjunction with an output meter of conventional design, is ideal for the purpose.

The R.F. circuits are aligned by plunger type air trimmers. A special tool Part No. 5371 is available for the alignment of air-trimmers. It is constructed of steel, with the adjustment tool on end and a deep centred socket wrench for locking the trimmer on the other. Owing to the construc-

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RESISTANCE MEASUREMENTS.

The resistance values shown in fig. 5 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. 5.—Resistance Diagram.

Resistance values were taken with valves removed, variable condenser in full mesh, volume control in maximum clockwise position and sensitivity switch at Local (L.)

SOCKET VOLTAGES.

VALVE	Bias Voltages	Screen Grid to Chassis Volts	Plate to Chassis Volts	Plate Current M.A.	Heater Volts
6A7 Detector M.W.	5.0†	85	240	1.5	6.3
S.W.	3.0†	80	240	2.5
Oscillator	'	-	160	3.5
6D6 I.F. Amplifier
	4.5†	85	240	3.0	6.3
S.W.	3.0†	80	240	4.0
6B7 Reflex Amplifier	5.5	65*	80*	2.5	6.3
42 Pentode	—18‡	240	220	30.0	6.3
80 Rectifier	600/300	) volts 50	) ma total	current	5.0
	Voltage	across L	.S. field	80 volts

*Cannot be measured with ordinary voltmeter.

‡Control Grid to chassis. Cannot be measured with ordinary voltmeter. †Cathode to chassis.

Measured at 240 volts A.C. supply. No signal input. Volume control in maximum clockwise position and sensitivity switch in distant (D) position.

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tion of air trimmers and their locations on the receiver chassis, alignment without the aid of this tool will be difficult. It will be found advantageous in adjusting the air-trimmers to rotate the plunger during the operation, in addition to using a steady pressure. As soon as the correct capacity is obtained, lock the trimmer with the tool to make the setting permanent.

The I.F. transformers and the oscillator circuit, at 600 K.C., are adjusted by magnetite cores inserted within the windings. The adjustment screws are shown in figs. 1 and 3, and these require the use of a non-metallic screwdriver, since the selfcapacity of a metal screwdriver will render accuracy most difficult. A special tool part No. 5372 is also available for this purpose, which in addition to being non-metallic fits conveniently over the adjustment screw, simplifying the operation.

See that a 250,000 ohms resistor is connected between the output terminals of the test oscillator.

Connect the ground connection of the test oscillator to the chassis of the receiver during alignment, and when aligning the I.F. stages, remove the grid clip from 6A7 before connecting the oscillator.

Perform alignment in the proper order, starting with No. 1 and following all operations across,

then No. 2, etc. Adjustment locations are shown in figs. 1 and 3. Keep the volume control set in the maximum clockwise position and regulate the output of the test oscillator so that a minimum signal is applied to the receiver to obtain an observable output indication. This will avoid A.V.C. action and overloading.

"Approx. 550 K.C. no signal," mentioned in the chart, means that the receiver should be tuned to a point at or near 550 K.C. where no signal or interference is received from a station or local (Heterodyne) oscillator.

The term "Dummy Aerial" means the device which should be connected between the output cable of the Modulated Oscillator and the aerial terminal of the Receiver, on short waves only, to simulate the characteristics of the average aerial. The "Dummy Aerial" in this case is a 400 ohms non-inductive resistor.

To check the calibration of the receiver, connect an aerial and an earth wire and tune a broadcasting station of frequency between 700 and 550 K.C. If an error is apparent, re-set the pointer by loosening the set screw. Then repeat adjustments 8 and 9 of the chart.

Fig. I.—Lay-out Diagram (top view).

Alignmer Order	Oscillator Connection to Receiver	Oscillator Setting	Receiver Dial Setting	Circuit to Adjust	Adjustment Symbol	Adjust . to Obtain
Ч	6A7 Grid Cap	460 K.C.	Approx. 550 K.C. No signal	3rd I.F. Trans.	LI4	Max. (peak)
2	6A7 Grid Cap	460 K.C.	Approx. 550 K.C. No signal	3rd I.F. Trans.	LI3	Max. (peak)
3	6A7 Grid Cap	460 K.C.	Approx. 550 K.C. No signal	2nd I.F. Trans.	LI2	Max. (peak)
4	6A7 Grid Cap	460 K.C.	Approx. 550 K.C.	2nd I.F. Trans.	LII	Max. (peak)

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Alignmen Order	Oscillator t Connection to Receiver	Dummy Aerial	Oscillator Setting	Receiver Dial Setting	Circuit to Adjust	Adjustment Symbol	Adjust to Obtain
5	6A7 Grid Cap		460 K.C.	Approx. 550 K.C.	Ist I.F. Trans.	LI0.	Max. (peak)
6	6A7 Grid Cap	-	460 K.C.	Approx. 550 K.C. No signal	lst I.F. Trans.	L9	Max. (peak)
		Repea	t the above	adjustments before \|	proceeding.
7	Aerial Term.		600 K.C.	600 K.C.	Oscillator	L6 Osc. 600 K.C	Max. (peak)
8 9 10	Aerial Term. Aerial Term. Aerial Term.		1400 K.C. 1400 K.C. 600 K.C.	1400 K.C. 1400 K.C. 600 K.C.†	Oscillator Detector Oscillator	C15 C4 L6 Osc. 600 K.C	Max. (peak) Max. (peak) Max. (peak)
		Repea	at adjustment	s 8 and 9 before pr	roceeding.
	Aerial Term.	400 ohms.	18 metres	18 metres	Oscillator Detector	Ć18 C5	Max. (peak)* Max. (peak)t

† Rock the tuning control back and forth through the signal. * Use minimum capacity peak if two peaks can be obtained. • Use maximum capacity peak if two peaks can be obtained.

CIRCUIT MODIFICATION.

All receivers of these models produced after 8/3/38 inst., include the following modification. Instructions are given for making the alteration to receivers produced prior to this date.

(1) Condenser C33 removed and replaced with I.F. filter, part No. 5441. The filter requires only one hole for mounting. The lower rivet of the two which fasten the cover plate at the rear of the chassis should be removed and the hole used.
(2) Resistor R16 changed to 1 megohm 1 watt.
(3) Resistor R19 changed to 250,000 ohms 1 watt.
(4) A 250,000 ohms 1 watt resistor connected from screen grid of 6B7 to chassis.

The connections of the Volume Control R17 and resistor R18 are rearranged, the Volume Control now being in the diode circuit and R18 in the grid circuit of the 6B7. No extra leads are necessary to make the alterations, which are as follows:

(1) Disconnect R18 from where it joins C32 and connect it to the third tag on the panel to which its other end is still connected. This should place R18 between tags one and three on the panel.
(2) Remove the black lead in the Volume Control shielded cable from the third tag on the panel and connect it to the point on C32 from which R18 was removed.

In the case of the Radiola 163 condenser C42 should be removed from the panel and connected to the abovementioned point on C32.

IMPORTANT.

On completion of the modification it will be necessary to re-align the intermediate frequency stages at 460 K.C.

SHORT WAVE INSTABILITY.

Reference to the circuit code will show a .02 ufd. paper condenser connected in parallel with C28. This has been done to provide a more efficient filter, giving greater stability on the high frequency end of the short wave band and became effective on the 17/3/38.

Fig. 4.—Circuit Modification.

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		N
Code	Part	COILS	Code	Part	RESISTORS	Code	Part	CONDENSERS
L1, L2 L3, L4 L5, L6 L7, L8 L9, L10 L11, L12 L13, L14	4353 4331 4354 4322 4327 4327 4329	Aerial Coil, 1500-550 K.C. Aerial Coil, 16-50 metres Osc. Coil, 1500-550 K.C. Osc. Coil, 16-50 metres First I.F. Transformer Second I.F. Transformer Third I.F. Transformer	R12 R13 R14 R15 R16 R17 4285 R18 R19	1.75 megohms, ¹ / ₃ watt 1.75 megohms, ¹ / ₃ watt 1.75 megohms, ¹ / ₃ watt 2,000 ohms, ¹ / ₃ watt 500,000 ohms, 1 watt 250,000 ohms, Vol. Control 300,000 ohms, ¹ / ₃ watt 100,000 ohms, 1 watt	C13 C14 C15 C16 C17 C18 C19 C20	C13 C14 C15 3661 C16 C17 C18 3658 C19 C20 4326 (52)	115 mmfd. Mica (A) 130 mmfd. Mica (H) 2-20 mmfd. Air Trimmer 14 mmfd. Mica (C) 440 mmfd. Mica (Padder) 2-10 mmfd. Air Trimmer 3500 mmfd. Aira (Padder)
		TRANSFORMERS	R20 R21 R22	4284	20,000 ohms, 1 watt 300,000 ohms, 1 watt	C20 C21 C22	4328 (163)	.1 mfd. Paper .1 mfd. Paper .1 mfd. Paper
TI TI TI T2	4321 A 4323 A 4325 A	Power Transformer 50-60C. Power Transformer 40C. Power Transformer 110V. Loudspeaker Transformer T.G.52 (52), T.G.113 (163)	R22 R23 R24 R25 R26	+284	100,000 onms, Tone Control 400 ohms, 3 watt W.W. 1 megohm, 1 watt (163) 20,000 ohms, 1 watt (163) 600 ohms, 3 watt (163)	C23 C24 C25 C26 C27 C28		115 mmfd. Mica (A) 130 mmfd. Mica (H) 200 mmfd. Mica (J) 50 mmfd. Mica (D) .05 mfd. Paper 25 mfd. 25V. Elect. with .02
		RESISTORS			CONDENSERS	C29 C30		I mfd. Paper in Parallel I mfd. Paper 115 mmfd. Mica (A)
R I R2 R3 R4 R5 R6 R7 R8 R9 R10 R11		100,000 ohms, $ watt 2,000 ohms, $ watt 200 ohms, $ watt 100,000 ohms, $ watt 400 ohms, $ watt 60,000 ohms, $ watt 20,000 ohms, $ watt 20,000 ohms, $ watt 20,000 ohms, $ watt 30,000 ohms, $ watt 30,000 ohms, $ watt	C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12	3658 3661 4326 (52) 4328 (163)	500 mmfd. Mica 500 mmfd. Mica 4 mmfd. Mica (1) 2-10 mmfd. Air Trimmer 2-20 mmfd. Air Trimmer .05 mfd. Paper Variable Condenser .05 mfd. Paper .1 mfd. Paper 8 mfd. 450 volt Electrolytic .05 mfd. Paper 110 mmfd. Mica (L)	C31 C32 C33 C34 C35 C36 C37 C38 C39 C40 C41 C42		130 mmfd, Mica (H) 200 mmfd, Mica (J) 700 mmfd, Mica (J) 705 mfd, Paper 25 mfd, Paper 25 mfd, Paper 25 mfd, Paper 35 mfd, Paper .5 mfd, Paper 8 mfd, 500 V. Elect. .05 mfd, Paper (163)

Fig. 2.—Circuit Diagram and Code.

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