# Espey Mfg. Co., Inc. 7B-12 Schematic

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Price: 7.20 In stock  Model: 7B-12 Manufacturer: Espey Mfg. Co., Inc. ## Schematic Pages ## Schematics Content: Please note: this content is a computer-generated interpretation of the above schematic and is provided only to help assist you in locating this schematic. For the actual text, please consult the schematic above. Thank you. #### Page 1: iESPIEY PAGE 19-3 ESPEY MFG. coMPANY, INCA MODEL 7342 LAFAYETTE SCHEMATIC DIAGRAM FWW INCH ANTENNA EXIUHAL #### Page 2: This Receiver features the latest in A. M. f F. M., Receiver Design. Eleven (11) tubes plus a Rectifier are used in the A, M. g F. M. superheterodyne Circuit. separate antennas are supplied for A. M. and F. M. An automatic frequency control tube is used to stabilize the F. M. and simplify tuning. TUBE COMPLEMENT: l Type (iBAG  F. M. R F. Amplifier l Type 7FS - F. M. Converter 1 Type 7Q7 f A. M. Converter 1 Type 6C4 f$- Automatic Frequency Control l Type 7AH7 >$ l. F. Amplifier l Type oSH7 - Detector Driver (PM) l Type (SSQ7  lst Audio Amplifier, A. M. Detector l Type 7A6 f" Ratio Detccfor l Type 7F7  2nd Audio Amplifier and phase inverter 2 Type 7C5 -ff Beam power output. l Type 5Y3/GT W' Rectifier. T. OPERATING CONTROLS: 1) The "ON'OFF" power switch and Tone Control is the knob at the extreme left of the set. Turn this conf trol in a clockwise direction until the switch clicks and thc dial becomes illuminated. Turning this control further in the same direction will change the tone. the left. will increase the volume. 3) The Band Switch is the third knob from the left. The extreme counterclockwise position of this knob is for phonograph operation. The center position is for FM reception. The extreme clockwise position is for The Volume Control is the second knob from Turning this control in a clockwise direction 4) The Tuning Control is the extreme right hand knob. Turning this knob in either direction will move the dial pointer and select the stations on the A. M. or In most cases it will not be necessary to use external antennas. since the receiver is equipped with a loop anI tenna for AM reception and an indoor type folded dipole antenna for FM reception. When inadequate reception is obtained from a desired station, it maybe necessary to reposition the antennas to ' meter favor that station. On AM, the loop should be turned so that the edge faces toward the station desired. On FM, the entire cabinet should be positioned so that the back is hroadside to the direction from which the signals are For the reception of weak or distant stations, or for the operation of the receiver in unfavorable locations, provisions are made for the use of external antennas. The folded dipole should be disconnected when an e>tV tcrnal FM antenna is employed. Do not disconnect the AM loop when an external antenna is used on standard broadcast. Futlitre of the Reccibcv to opertlle may be doe to. l) All tubes not firmly in sockets Z No current at power socket. 3) Band Switch in wrong position. 4) Speaker not plugged in. 5) Antennas not attached. 6) Defective fuse in Receiver, 4* ALIGNMENT PROCEDURE FOR A. M.: Equipment Required: l. Set band switch to AM, advance volume control to full volume setting Broadcast Band Signal Generator, Output Meter. 2 Connect output inctcr across Voice coil 3. Conncct the Signal Generator across thc broadcast band antenna (Rear) section of the variable condenserv The "high" side of the Generator should connect to the Stator section and the "ground" side to the chassis. Adjust the Signal Generator to 453 kc and with the receiver switched on, adjust the first and second l. F> transformers for peak output as shown on the output The signal injected into the receiver should be as small in magnitude as possible. consistent with a useful deflection on the output meter. 4. Connect the. "high" side of the Generator to thc antenna terminal with a 200mmf condenser inserted in series.. Connect the "ground" side of the Generator to the chassisv Tune receiver to 60 on the dial, adjust Sig' nal Generator to GOOkc. Adjust the BC antenna coil for maximum deflection on the output meter, Use a weak (C)John F. Rider #### Page 3: 5. Tune receiver to 160 on the dial. Adjust Signal Generator to 1600kc. Adjust BC oscillator and BC anr tenna trimmers for maximum output. 6, Repeat operations 4 and 5. 5A ALIGNMENT PROCEDURE FOR F. M.: NOTE: Points A, B. C. D. E. F. G. and H are noted on civcuit diagram. Points C, and D have been bfought out to the unused contacts of the speaker socket at the 'rear of the chassis. Equipment Required: a) High frequency Signal Generator With 88/108 Mc tuning range. b) Signal Generator capable of delivering .l Volt c) Audio output meter. d) D. C. vacuum tube voltmeter with zero center c) Tuning wand. Disable AFC. dining alignment of FM. circuits by short circuiting point "B" to chassis. A. Ratio Detector Alignment: 1. Connect V.T.V.M. across point "C" and ground, 2. Feed 10.7mc unmodulated R.F. Signal into 6H7
grid (point A) through .Ol ufd. condenser. This signal
should be .1 volt.

3. Adjust primary of Ratio Detector (T15) for maxif
mum voltage indication on V. T. V. M.

4. Connect zero centered V. T. V. M. across point
"D" and ground.

5. Adjust secondary of Ratio Detector (TfS) for zero

6. Tune 10.7mc Signal Generator higher in frequency

on V. T. V. M.; note this voltage, then tune signal genI

opposite polarity is obtained. Note this voltage, then if
necessary re'adjust primary of the Det. (T'S) until the
voltages are about equal on either the high or low side of

(C)John F. Rider

erator lower in frequency until maximum voltage Of thev

EsPEY PAGE 19$5 MODEL 'IB-12 1. Shunt a 1,000'ohm carbon resistor across the priml ary of the detector (TfS) (Points G and H). 2. Connect output meter across speaker voice coil. 3. Volume and tone controls at maximum clockwise 4. Connect 10.7mc (modulated 30%) signal genera' tor through .Olufd condenser across point "F" and 5. Adjust secondary, then primary of (T13) for maxir mum audio output. (Reduce input signal to maintain output at .waatt level.) 6. Connect 10.7mc 30?/o modulated signal generator across point "E" and ground. 7. Adjust secondary, then primary of (T$1) for maxi'
mum audio output. (Reduce input signal to maintain
output at .Sewatt level.)

8. Remove 1000'ohm shunting resistor from across
primary of (T'S).

C` OSCILLATOR AND R. F. ALIGNMENT:

1. Connect V. T. V. M. across point "C" and ground,

2. Connect lO8mc signal generator to FM antenna
terminals. If generator impedance is low, put one 150'
ohm carbon resistor in series with each of the generator

3. Adjust FM oscillator trimmer (C'SI) for maxi'
mum V. T. V. M. reading.

4. Adjust FM Rf. trimmer (Cf52) for maximum
V. T. V. M. reading. During alignment reduce input
signal to maintain Detector voltage at 2.V.

5. Repeat steps 3 and 4.
6. Feed a 90mc signal into antenna terminals (as in
C12), tune receiver dial to signal.

7. Test R. F. coil with tuning wand and if necessary
adjust spacing of FM R.F. coil (L14) for maximum V.T.
V.M. reading at 90mc. During alignment reduce input
signal to maintain Detector voltage at 2.V.

8. Repeat steps 2 and 4 if necessary.
9. Remove A.F.C. shorting jumper.

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