Summary of Contents for Elenco Electronics AR-2N6K
- Page 1 FM RECEIVER KIT MODEL AR-2N6K Assembly and Instruction Manual Elenco Electronics, Inc. Copyright © 2003, 1995 Elenco Electronics, Inc. Revised 2003 REV-D 753001...
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Page 2: Parts List
PARTS LIST If you are a student, and any parts are missing or damaged, please see instructor or bookstore. If you purchased this FM receiver kit from a distributor, catalog, etc., please contact Elenco manual) for additional assistance, if needed. - Page 3 THE AR-2N6 It is the goal of this project to educate the builder in all of the principles needed to design and build this kit. The radio is broken down into four blocks. Each block contains: 1. Explanation of circuit to be assembled (Theory of Operation).
- Page 4 Narrow Band The selectivity of the entire system is limited to only enough frequencies to pass voice or low frequency data. A normal FM receiver would have a bandwidth large enough to pass music and high frequency data transmissions. FM Radio Receiver The letters “FM”...
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Page 5: Audio Amplifier
BLOCK 1 - THE AUDIO AMPLIFIER THEORY OR OPERATION The audio in this radio is amplified by using an integrated circuit audio power amplifier. The LM-386 specifications are as follows: • Single supply voltage (4-12V) • Idle current - 4 milliamps •... - Page 6 ASSEMBLY INSTRUCTIONS FOR BLOCK 1 Solder the parts to the PC board and put a check mark in the box (!) next to each step after it is completed. The parts should be similar to the sketch in each box, but will differ in size. Be sure to check each solder point for shorts and cold solder connections.
- Page 7 CONNECTING PARTS TO THE BACK SIDE OF THE PC BOARD Twist two leads of a 10 resistor and a .047 F capacitor as shown in Figure 8a. Solder the wires close to the components and clip off any excess wire. Solder (brown-black-black-gold) Mount the components shown in Figure 8 to the foil side of the PC board.
- Page 8 CONNECTING THE FRONT PANEL PARTS TO THE PC BOARD Solder the parts to the PC board and put a check mark in the box (!) next to each step after it is completed. The parts should be similar to what is shown in Figure 9. To wire the speaker, pot and switch, cut the indicated length of wire from the roll of 22 gauge solid wire and strip 1/4”...
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Page 9: Power Test
TEST PROCEDURE - BLOCK 1 Procedure 1 If you do not have an audio generator and multimeter, skip to procedure 2. Power Test Make sure that the power switch is in the OFF position (handle away from the 2 wired terminals). Connect a fresh 9V alkaline battery to the battery snap. -
Page 10: Power Output
Power Output If you do not have an audio generator and an oscilloscope, skip this test. Make sure that the power is OFF and connect the audio generator and the oscilloscope as shown in Figure 11 (replace the multimeter leads with scope leads). generator to 400Hz minimum output and set the oscilloscope to read 1V/div. - Page 11 Frequency Response If you do not have an audio generator and an oscilloscope, skip this test. Make sure that the power is OFF and connect the audio generator and the oscilloscope as shown in Figure 11 (replace the multimeter leads with scope leads). generator to 400Hz minimum output and set the oscilloscope to read 1V/div.
- Page 12 9V Battery QUIZ 1 1. The impedance of a 200 F capacitor at 100Hz is: (a) 50 (b) 79.6 (c) 2 2. If the frequency is 150MHz, the wavelength is approximately . . . (a) 20 meters (c) 6 meters (b) 2 meters (d) need more information 3.
- Page 13 BLOCK 2 - RECOVERING THE DATA Theory of Operation In dealing with FM receivers, there are some terms that must be defined. First, let’s determine the term deviation as the frequency swing of the incoming FM signal. When no modulation is present, the incoming signal is a fixed frequency carrier wave (Fc) .
- Page 14 Linear Area Narrow Band Notice how the linearity improves for a given amount of frequency deviation when the positive and negative peaks are further apart. Figure 16 also shows how the amplitude of the output would drop for the same frequency deviation on a more linear detector.
- Page 15 ASSEMBLY INSTRUCTIONS FOR BLOCK 2 Turn the switch OFF and remove the battery. Solder the parts to the PC board and put a check mark in the box (!) next to each step after it is completed. The parts should be similar to the sketch in each box, but will differ in size.
- Page 16 CONNECTING THE SQUELCH CONTROL TO THE PC BOARD Cut two 3” pieces of wire from the roll of 22 guage soild wire and strip 1/4” of the insulation off of each end. Using these wires, solder the 100k potentiometer (VR1) to the PC board and put a check mark in the box (!) after both wires are in Make a good mechanical connection before soldering.
- Page 17 TEST PROCEDURE - BLOCK 2 Procedure 3 If you do not have a multimeter, skip to procedure 4. DC Test Make sure that the power switch is in the OFF position. Reconnect the 9V battery to the battery snap. Set the multimeter to read on the 20V scale and connect to the circuit as shown in Figure 20.
- Page 18 AC Test If you do not have a signal generator, skip to procedure 4. Make sure that the power switch is in the OFF position. Turn squelch counterclockwise . Set the mulitmeter to read 20VDC full scale and connect to the circuit as shown in Figure 21.
- Page 19 Squelch Control Check The function of the squelch control is to eliminate static when there is no signal present. This control sets the level of passable signals. The squelch control works by raising the voltage to the ( to the audio amplifier and thus disabling the amplifier output.
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Page 20: Theory Of Operation
QUIZ 2 1. When no FM modulation is present, the incoming signal frequency is . . . (a) DC (b) fixed (c) minimum (d) maximum 2. An increase in the carrier frequency due to modulation is called . . . (a) detection (b) negative deviation (c) positive deviation... - Page 21 ASSEMBLY INSTRUCTIONS FOR BLOCKS 3 & 4 Turn the switch OFF and remove the battery. Solder the parts to the PC board and put a check mark in the box (!) next to each part after it is installed. The parts should be similar to the sketch in each box, but will differ in size.
- Page 22 ASSEMBLY INSTRUCTIONS FOR BLOCKS 3 & 4 (Continued) R9 - 0 Jumper Wire Use a discarded resistor lead. Figure 24 R10 - 1k Resistor (brown- black - red - gold) -21- L2 - Turnable Coil L3 - Turnable Coil R4 & R6 - 4.7k Resistor (yellow - violet - red - gold) C5 - 3.9pF Capacitor (3.9)
- Page 23 FINISHING PC BOARD ASSEMBLY Cut three 3” pieces of wire from the roll of 22 gauge solid wire and strip 1/4” of insulation off of each end. Using these wires, solder the 5k potentiometer (VR2) to the PC board and put a check mark in the box (!) after all of the wires are in place.
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Page 24: Front Panel Assembly
CONNECT COMPONENTS TO THE PC BOARD Cut six 1” pieces of 22 gauge wire and strip 1/4” of insulation off of each end. Connect the wires to the remaining DPDT switch as shown in Figure 26a. Insert the six wires into holes F through K and solder to the PC board as shown in Figure 26b. - Page 25 Speaker Phono Jack Nut 4-40 Nuts 4-40 Nut #4 Lockwasher Ground Terminal #4 Lockwashers “L” Bracket “L” Brackets Lockwasher 4-40 Screws (black) Phono Jack Figure 27 Figure 28 Figure 29 -24-...
- Page 26 5/16” Internal Tooth Front Panel Tuning Pot (5k ) Lockwasher Volume Pot (100k ) 2M/6M Switch 2-56 Nuts Flat Washers Squelch Pot 7mm Hex Nut 2-56 Nuts 2-56 Screws On/Off Switch Large Tuning Knob 5/16” Internal Tooth Lockwashers 2-56 Screws 7mm Hex Nuts Volume Knob Squelch Knob...
- Page 27 FINAL TEST AND ALIGNMENT Attach a two foot or longer length of wire to the male RCA plug and connect it to the radio antenna jack. Install a fresh battery and turn the power ON. Make sure that squelch counterclockwise and the volume control is set at mid-position.
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Page 28: Schematic Diagram
SCHEMATIC DIAGRAM Elenco Electronics, Inc. 150 W. Carpenter Avenue Wheeling, IL 60090 (847) 541-3800 Fax: (847) 520-0085 http://www.elenco.com e-mail: elenco@elenco.com...