Vectronics_VEC-102K_user.pdf

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1、VEC-102K World Band Receiver Instruction and Kit Assembly Manual Table of Contents Receiver Features.2 Introduction No. 1: For Beginners.3 Introduction No. 1: For Hams, Experienced Experimenters.6 Schematic Diagram of VEC- 102K.8 Receiver Controls.9 Understanding and Using the Regeneration Control.1

2、1 Tuning SSB Voice Signals.12 Some Helpful Terms notice that there are 5 band switch positions but no coil taps or second windings! Elimination of antenna trimmer so critical in most regenerative designs. We replaced the traditional trimmer with an RF gain pot that has little effect on frequency or

3、regeneration. Manageable, tame regeneration control circuit. Regeneration begins smoothly with no pop and has a comfortable adjustment range. 7 The result, we think, is a receiver design which bridges the classic simplicity of regeneration to the performance demands of the 1990s. Heres how we did it

4、: In brief, the circuit uses RF regeneration and high levels of DC feedback. Notice that the antenna is coupled directly to the source of RF amplifier FET Q3 rather than through the L- C tuning network. Direct coupling of the drains of Q1 and Q3 isolates the L- C circuit from the antenna input, enha

5、ncing stability and greatly minimizing RF oscillator output to the antenna. Such RFI has been a serious problem in traditional regenerative circuits which permitted the oscillating detector to behave as an unstable but potent QRP transmitter. R4 reduces the Q of L1 (10 H) for smoother regeneration.

6、The SW1 bandswitch selects a combination of simple inductors. For example, the total inductance for Band A is L1+L2+L3+L4+L5. The inductance for Band E is only L5. And so forth. Air variable C1 uses its 50 pF range and mechanical vernier reduction to provide smooth bandspread in parallel with C3 and

7、 trimmer C5 which perform the traditional bandset function. Trimmer pot R20 ensures adjustability for smooth regeneration over all tuning ranges, regardless of individual FET characteristics. C17, C9, C10 and R9 form a low pass filter to block RF from the audio amplifier and provide basic audio filt

8、ering. Volume Control R2 varies OUTPUT rather than low- level input to the LM386 audio amplifier. This approach further isolates the RF stages from variations in the audio section. The LM386 (IC1) circuitry employs all recommended options for maximum gain and protection from self- oscillation. To pr

9、olong useful battery life, R13 limits current draw by the LED (CR1) to minimum reasonable visibility as an on/off indicator. 8 Schematic Diagram 9 Receiver Controls and Connections Most of the controls are self explanatory. However, it is very important to understand the correct use of the Regenerat

10、ion Control and the two internal trimmer adjustments of the receiver. BANDSWITCH (SW1) This quality rotary switch selects any one of the 5 tuning ranges from A to E indicated on the tuning scale. TUNING (C1) The Tuning knob controls an air- variable capacitor (C1) which also has a built- in 6:1 vern

11、ier reduction drive to which the dial pointer is attached. This reduction permits very smooth tuning. The frequency markings on the dial scale must be understood to be approximate due to the 10% tolerance ratings of the fixed inductors (L1 through L5). PUSH SWITCH (SW2) AND L.E.D. INDICATOR (CR1) Wh

12、ile the purpose of the on/off switch and LED is obvious, remember to turn your receiver OFF when not in use. A weakened battery degrades receiver performance. REGENERATION (R1) Because understanding and controlling regeneration is at the heart of your receivers performance, weve provided a separate

13、section on its use. In brief, it controls receiver sensitivity and adjusts between AM broadcasts and CW- SSB. VOLUME (R2) This potentiometer performs the normal function of any volume control. Of interest to the technically- minded, it controls the output of the LM386 audio IC, rather than the input

14、, which enhances the stability of the regenerative detector. RF GAIN (R19) This trimmer potentiometer is adjustable with a small screwdriver. Maximum gain is clockwise when viewing the rear panel. A good normal setting is 3/4 of its full rotation. If you are using a marginal antenna (5 to 10 feet of

15、 wire indoors), keep R19 at its maximum setting. If you are using a very good antenna (a long, high outdoor wire or ham antenna), keep R19 at about 2/3 or so of its range. If your listening interests require frequent RF gain adjustments, install an external 10K control in series with your antenna. R

16、EGENERATION RANGE TRIMMER (R20) Ordinarily, this trimmer is adjusted only after kit construction or in the unlikely event that any of the FET transistors are replaced. This adjustment assures smooth regeneration over all five of the tuning ranges. See Construction Phase 5. 10 DIAL CALIBRATION TRIMME

17、R (C5) This one- time internal adjustment is made with a miniature screwdriver in order to assure that the frequency markings on the front panel are as accurate as reasonably possible. EARPHONE JACKS (J2,J3) These two jacks accept 1/8 (3.5 mm.) stereo plugs as used in Walkman type headphones or mini

18、- speaker systems. The audio output is monaural; the two jacks are wired in parallel to permit the use of two headphones. Note: if a mono 1/8 plug is used for any reason, it must NOT be pushed all the way in, or it will short out the audio. ANTENNA CONNECTOR (J1) This binding post permits easy hooku

19、p of any wire, or a banana plug may be inserted in its end. 10 to 20 feet of ordinary hookup wire (also called bell wire) provides good basic reception, even when installed indoors. See the section on Antennas in this book for more information. GROUND CONNECTION For casual operation, a ground connec

20、tion is optional. However, a wire from this connector to a ground rod or cold water pipe will reduce unwanted noise and interference from nearby electrical devices or AC wiring and may boost receiver sensitivity. Attach the wire between the two washers, then tighten the wing nut. 11 Understanding se

21、e below. Detector: the section of any radio that changes radio energy into audio energy intended for listening. Direct Conversion: a popular type of simple receiver for CW- SSB which needs no regeneration control, but which does not permit pleasant listening to AM shortwave broadcast, because the ca

22、rrier (see above), as well as the voice modulation, can be heard. Electrolytic (capacitor): a capacitor containing an acid or salt paste (electrolyte) and is generally polarized with a positive and negative side. Correct polarity must be observed when installing electrolytic capacitors. FET: Field E

23、ffect Transistor Ground: Refers to all points and surfaces in an electronic device which are connected to the - DC side of the power supply or battery. A ground plane of a circuit board is the large area of copper plating that is common to ground. Earth ground refers to water pipes or metal groundin

24、g rods in direct contact with Earth. IC, Integrated Circuit: A tiny plastic rectangular block with 6, 8, 14, or more pins, containing a silicon chip which provides the equivalent of dozens, or hundreds, of individual transistors and resistors. 14 Install: in modern kit building, this ward means 1. S

25、elect correct part 2. Insert it in its circuit board position, oriented correctly. 3. Solder all points 4. Trim or nip away excess wire lengths K: abbreviation for 1000 ohms. (10K = 10,000 ohms). KHz: KiloHertz, a thousand hertz MHz: MegaHertz, a million hertz Inductor: A coil or loop or wire used i

26、n electronic circuits. Oscillator: see Regeneration pF: picofarad, a tiny unit of capacitance. megohm: one million ohms Regeneration, Regenerative: a method of boosting the performance of a simple detector by feeding the detected signal back to the input of the detector for further amplifying. This

27、oscillation process must be controlled carefully through the use of a regeneration control. RF: Radio Frequency Energy, in contrast to audio or DC. RTTY: Radio Teletype SSB, Single Sideband: a method of voice transmission which eliminates the carrier (whistle) which you hear in an AM broadcast if th

28、e regeneration control is turned too far to the right. Tolerance: the manufacturing accuracy for electronic (and other) parts. Tolerance ranges from 20% down to better than 1% of the value marked on the part. Toroid: a type of coil consisting of wire wrapped around a donut- shaped form, such as L5 i

29、n this receiver. Trimmer: a miniaturized variable resistor or capacitor used for occasional circuit adjustments. F: microfarad, the usual unit of capacitance. H: microhenry, a unit of inductance. WWV: U.S. government broadcasting service which provides exact time by voice announcement each minute on

30、 very exact frequencies such as 5, 10, 15, and 20 MHz. 15 VEC-102K Parts Lists Please check and organize your kit parts before soldering. FIXED CAPACITORS ? 1 - 33pF disc C6 ? 1 - 47pF monolithic (marked 47 or 470) C3 ? 1 - 75pF disc C16 ? 2 - .0033F polystyrene (rectangular) C9,C17 ? 4 - .01F disc

31、(marked 103Z) C7,C8,C21,C28 ? 5 - .1F DISC (marked 104Z) C2,C4,C10,C11,C15 ? 1 - 1F electrolytic C18 ? 1 - 10F electrolytic C14 ? 1 - 22F electrolytic C12 ? 1 - 100F electrolytic C13 ? 1 - 470F electrolytic C19 RESISTORS ? 1 - 10 ohm (brown- black- black) R17 ? 1 - 15 ohm (brown- green- black) R12 ?

32、 1 - 22 ohm (red- red- black) R11 ? 2 - 1K ohm (brown- black- red) R6,R9 ? 1 - 2.2K ohm (red- red- red) R13 ? 4 - 10K ohm (brown- black- orange) R3,R4,R5,R8 ? 1 - 1M ohm (brown- black- green) R7 INDUCTORS ? 1 - 10H molded (brown- black- black- silver) L1 ? 1 - 3.3H molded (orange- orange- gold- silv

33、er) L2 ? 1 - 1H molded (brown- black- gold- silver) L3 ? 1 - .47H molded (yellow- violet- silver- silver) L4 ? 1 - T- 52- 2 iron powder toroid and wire to make L5 SEMICONDUCTORS ? 3 - FET (field- effect transistor, type J310) Q1,Q2, Q3 ? 1 - LM386 audio amplifier IC IC1 ? 1 - LED (light emitting dio

34、de) CR1 CONTROLS we got started, and weve made sure that this receiver will tune correctly. Construction Phase 2 (Steps 2-1 through 2-20) The parts in Phase 2 are the heart of your receiver; working together with the tuning circuit begun in Phase 1. Building this section is simply a matter of identi

35、fying and installing the parts correctly. This phase includes all three FET transistors and one electrolytic capacitor, all of which are to be installed in one correct way only. You really cant go wrong; simply position the transistors and electrolytic capacitors exactly as illustrated, right on the

36、 board. ? ? 2- 1. Install R5, 10K (brown- black- orange). ? ? 2- 2. Install C7, .01F (body marking 103M). ? ? 2- 3. Install C18, 1F electrolytic. Notice that the negative (- ) side is clearly marked on the capacitor, and that the (+) position is marked on the PC board. ? ? 2- 4. Install R3, 10K (bro

37、wn- black- orange). ? ? 2- 5. Install R6, 1K (brown- black- red). ? ? 2- 6. Install R17, 10 ohm (brown- black- black). ? ? 2- 7. Install C6, 33pF (body marking 33K). 21 ? ? 2- 8a. The locations for all three FET transistors (Q1, Q2, Q3) are imprinted clearly on the PC board. Notice the flat and roun

38、ded sides of the imprints, corresponding exactly to the shape of the transistors viewed from the top. Well install all 3 transistors in the following steps. (1.) Simply press each one into its 3 holes as far as it can reasonably go, (2.) gently bend the leads outward to secure it, (3.) solder all th

39、ree connections, and clip away the excess wires. Note: All three transistors are identical (Siliconix J310). ? ? 2- 8b. Install transistor Q1, per 2- 8a (above). ? ? 2- 9. Install transistor Q2, per 2- 8a (above). ? ? 2- 10. Install transistor Q3, per 2- 8a (above). ? ? 2- 11. Install R7, 1M ohm (br

40、own- black- green). ? ? 2- 12. Install C17, .0033F (body marking 332K). ? ? 2- 13. Install C8, .01F (marked 103M). ? ? 2- 14. Install R8, 10K (brown- black- orange). ? ? 2- 15. Install C21, .01F (marked 103M). ? ? 2- 16. Install C28, .01F (marked 103M) ? ? 2- 17. Install C2, 01F (marked 104Z) ? ? 2-

41、 18. Install R20, the 100K ohm regeneration trimmer (104B). This trimmer is identical in size and shape to the R19 RF gain control near the antenna jack. Be sure that its marking includes 104B as the last four digits, with the 4 as especially important. ? ? 2- 19. Install R19, the 10K ohm RF gain co

42、ntrol, near the rear corner of the PC board. Its marking includes the digits 103B. ? ? 2- 20. Install C16, 75pF (body marking 75J), near R19. 22 Construction Phase 3 (Steps 3-1 through 3-20) The following group of parts form the audio amplifier circuit which boosts the signal from the FET transistor

43、s to useful listening volume. ? ? 3- 1a. Examine the 8- pin socket for the LM386 IC and notice the rectangular notch at one end. This notch should be oriented in exactly the same direction as imprinted on the board (toward C14). Press the socket pins into their 8 holes so that the socket rests flat

44、on the board. You may wish to slightly bend two or more pins after insertion so that the socket wont slip out. ? ? 3- 1b. After making sure that all 8 pins are clearly visible on the bottom of the board, solder each connection carefully. Be sure not to let the solder tip touch two pins at the same t

45、ime, which would cause unwanted solder bridges. ? ? 3- 2a. In step 2- 3 above, you installed the first of the 5 electrolytic capacitors used in the receiver. The remaining 4 are of this amplifier section. Well install all of them now, so that the importance of correct (+) and (- ) positioning stays

46、fresh in mind. ? ? 3- 2b. Install C19, 470F per 3- 2a (above). ? ? 3- 3. Install C13, 100F per 3- 2a (above). ? ? 3- 4. Install C14, 10F per 3- 2a (above). ? ? 3- 5. Install C12, 22F per 3- 2a (above). ? ? 3- 6. Before proceeding, please double-check the polarity correctness for all 5 electrolytic c

47、apacitor! ? ? 3- 7. Install R11, 22 ohms (red- red- black). ? ? 3- 8. Install R12, 15 ohms (brown- green- black). ? ? 3- 9. Install C15, .1F (marked 104Z). ? ? 3- 10. Install C11, .1F (marked 104Z). ? ? 3- 11. Install C9, .0033F (body marking 332K). ? ? 3- 12. Install R9, 1K (brown- black- red). ? ? 3- 13. Install C10, .1F (marked 104Z). 23 About the Jumper Wires Several lengths of hookup wire are installed on the top side of the board between points marked W1, W2, etc. The purpose of such jumper wires is to make efficient connections across circuit traces