220 MHZ FM RECEIVER KIT Ramsey Electronics Model No. FR220 Keep an "ear " on the local repeater action from your easy chair with this simple and fun to build FM receiver. Tunes the entire 220 MHz band. Ideal way to "audition" before buying a rig! · · · · · · · · · · Tunes any 5 MHz portion of the 220 to 240 MHz band. Excellent receiver for new Novice classes! Excellent performance, less than 1 uV sensitivity. Tuned input, low noise preamp stage. True Dual-conversion superhet design with 2 pole Ceramic High IF and 6 pole Ceramic low IF filters! Front Panel Volume, Squelch, and Tuning controls. Excellent receiver for beginners and seasoned pros! Informative manual answers questions on theory, hookups, and uses - enhances resale value, too! Add our case set for a finished `Pro' look. Cases match all Ramsey products. Clear, concise assembly instruction carefully guides FR-220 1 you to a finished kit that ·works the FIRST time! PARTIAL LIST OF AVAILABLE KITS RAMSEY TRANSMITTER KITS · FM10A FM Stereo Transmitter · FM25B Synthesized FM Stereo Transmitter · AM25 Synthesized AM Transmitter · AM1 AM Transmitter RAMSEY RECEIVER KITS · FR1 FM Broadcast Receiver · AR1 Aircraft Band Receiver · AA7 Active Antenna · SC1 Shortwave Converter RAMSEY HOBBY KITS · SG7 Personal Speed Radar · SS70 Speech Scrambler · TT1 Telephone Recorder · SP1 Speakerphone · MD3 Microwave Motion Detector · TFM3 Tri-Field Meter · LC1 Inductance-Capacitance Meter RAMSEY AMATEUR RADIO KITS · HR Series HF All Mode Receivers · QRP Series HF CW Transmitters · CW7 CW Keyer · CPO3 Code Practice Oscillator · QRP Power Amplifiers RAMSEY MINI-KITS Many other kits are available for hobby, school, scouts and just plain FUN. New kits are always under development. Write or call for our free Ramsey catalog. FR220 FM RECEIVER KIT INSTRUCTION MANUAL Ramsey Electronics publication NO. MFR220 Rev. E1 First printing: February 1992 COPYRIGHT 1992 by Ramsey Electronics, Inc. 590 Fishers Station Drive, Victor, New York 14564. All rights reserved. No portion of this publication may be copied or duplicated without the written permission of Ramsey Electronics, Inc. Printed in the United States of America. FR-220 · 2 Ramsey Publication No. MFR220 Price $5.00 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR FR220 FM RECEIVER KIT TABLE OF CONTENTS Introduction to the FR220 .............. Circuit Description ......................... Parts List ........................................ Simplified Block Diagram .............. Parts Layout Diagram .................... FR220 Assembly Instructions........ Testing and Alignment ................... Enclosure Ideas ............................. Troubleshooting Guide .................. Notes for Advanced Users ............ Ramsey Kit Warranty..................... 4 5 6 8 9 11 21 24 24 25 27 RAMSEY ELECTRONICS, INC. 590 Fishers Station Drive Victor, New York 14564 Phone (585) 924-4560 Fax (585) 924-4555 FR-220 · 3 INTRODUCTION Because all but the most expensive scanners skip over the 220 MHz band, and most Ham rigs are 144 or 440 MHz, 220 is the long forgotten child. This nifty little receiver will allow you to check out 220 at a very affordable price! When you see how uncrowded the band is, and it's excellent VHF propagation characteristics, we're sure you'll order our 220 MHz transceiver and join in. This receiver is a good project for amateurs wishing to become more familiar with 220 Mhz FM before choosing a transceiver, or for those active on 220 who want an inexpensive receiver to take on trips, keep in a briefcase or to watch for band openings. Most Ramsey Electronics can be classified as "Skill Level 1" if we use the old Heathkit¦ guidelines for ease of assembly. That means that our kits are intended to be successful for first-time kit builders. This FR220 FM Receiver is best regarded as a "Skill Level 2" project, and should not be taken lightly, even by experienced, licensed radio amateurs. Still, this step-by-step manual is written with the beginner in mind, because we are well aware of the fascination with 220 MHz and its maze of repeaters holds for newcomers, which means this could be your very first kit project. The same holds true for those who just want to peek in on LOW VHF public service communications without the cost of a scanner. To be honest, we'd like to see first-time builders start out with an easier kit such as the Ramsey HR-40 Forty Meter receiver before assembling the FR220, but we are confident that you can construct the FR220 successfully if you follow this manual carefully and patiently. Before beginning the project or even studying the circuit description, it is worthwhile to develop some prior respect for how much receiver is packed onto the circuit board. The nine semiconductor devices (diodes, transistors and IC chips) give the equivalent of about 30 or more transistors and diodes. And, in addition to four inductors, a crystal and two ceramic filters, there are nearly 60 capacitors and resistors. Surely, all that should result in a decent receiver! You could easily spend twice the money plus hours of time trying to gather the equivalent parts from catalogs and still need to make your own circuit board. FR-220 · 4 BUILDING YOUR FR220 KIT There are just over 200 solder connections on the FR220 printed circuit board. That means your work could be 99% excellent and you could STILL have 2 or 3 cold solder points or solder bridges. Since this circuit is more sophisticated than a direct-conversion HF receiver or a simple transmitter, a beginner or casual amateur could have a harder time tracing a problem due to a poor solder connection. Therefore, PLEASE take us seriously when we say that good soldering is essential to the proper operation of your receiver! Use a 25-watt soldering pencil with a clean, sharp tip. Use only rosin-core solder intended for electronics use. Use bright lighting. A magnifying lamp or bench-style magnifier may be helpful. Do your work in stages, taking breaks to check your work. Carefully brush away wire cuttings so they don't lodge between solder connections. FR220 CIRCUIT DESCRIPTION VHF signals from the antenna are amplified through the tuned input circuit (L1,C3 and L2,C4) by Q1, a microwave bipolar transistor. Q1's output is fed to the input of the SA602 IC, an efficient single-package (8pin DIP) mixer-product detector-oscillator. The tunable oscillator section of the SA602 is aligned to operate at 10.7 MHz higher than the signal fed and amplified by Q1. For example, to receive 222-227 MHz signals, the oscillator must tune 232.7 to 237.7 MHz in order for the SA602's mixing capability to produce a steady 10.7 MHz output signal to the rest of the circuit. The oscillator frequency is determined by L3 and its associated capacitors, and varied by the varactor tuning network using D1 and varied by R1. The output from pin 4 of the SA602 passes through a ceramic 10.7 MHz filter, amplified by transistor Q2 and applied to input pin 18 of U2. Q3 provides AFC (automatic frequency control) by keeping the local oscillator of U1 from drifting away from an incoming signal. This is accomplished by tuning the varactor circuit in the direction opposite the drift. FR-220 · 5 The MC3359 IC has an internal oscillator controlled by the 10.245 MHz crystal. The 10.245 MHz signal is mixed with the 10.7 MHz input from U1 to convert down to the low IF of 455 KHz. The 455 KHz IF is filtered by FL2 and then amplified by a limiting amplifier in U2. Audio demodulation takes place in the quadrature detector, with L4 adjusting the detector. The audio modulation is detected in U2, and the background noise is used to control the squelch. U3 amplifies the audio output from pin 10 of U2 to a practical level for speaker or headphone operation. Pin 16 of U2 will ground the input of U3 when the squelch is closed. L4, a 455 KHz IF coil, permits adjustment of the 90-degree voltagecurrent phasing ("quadrature") of FL2's output to the FM detector demodulator (pin 8 of the MC3359). PARTS LIST Inductors 2 small 4 turn coils (L1,L2) 1 slug-tuned 3È turn coil (L3) 1 shielded transformer coil marked LB 53303 HK (L4) Semiconductors and IC's 1 3 1 1 1 1 1 2SC2570A or 2SC2498 transistor (Q1) 2N3904 transistor (Q2,Q3,Q4) SA602 8-pin IC (U1) MC3359 18-pin FM receiver IC (U2) LM386 8-pin audio amplifier IC (U3) Varactor diode, BB405 [small black body with white band] (D1) 1N914/1N4148 signal diode (D2) Special Components 1 10.245 MHz Crystal (Y1) 1 10.7 MHz ceramic filter [brown, molded, 3 leads] (FL1) 1 455 KHz ceramic filter [black, square] (FL2) FR-220 · 6 Fixed Resistors 1 2 ohm [red-black-gold] (R22) 3 270 ohm [red-purple-brown] (R6,9,20) 1 470 ohm [yellow-purple-brown] (R5) 2 1K ohm [brown-black-red] (R11,12) 3 10K ohm [brown-black-orange] (R7,17,19) 1 18K ohm [brown-gray-orange] (R18) 1 33K ohm [orange-orange-orange] (R14) 4 47K ohm [yellow-purple-orange] (R4,8,13,21) 1 100K ohm [brown-black-yellow] (R16) 1 470K ohm [yellow-purple-yellow] (R15) 1 1 megohm [brown-black-green] (R10) Capacitors 1 2 or 2.2 pf (C2,12) 4 4.7 or 5 pf (C1,5,9,10) 2 10 pf (C3,4) 1 22 pf (C19) 1 27 pf (C11) 2 100 pf [marked 100 or 101] (C6,22) 1 220 pf [marked 220 or 221] (C18) 6 .001 uf [marked .001 or 102 or 1nf] (C7,8,20,23,24,25) 8 .01 uf [marked .01 or 103 or 10nf] (C13,16,17,21,26,28,29,31) 1 .1 uf [marked .1 or 104] (C34) 1 1.0 uf electrolytic (C27) 3 4.7 or 10 uf electrolytic (C15,30,36) 4 100 to 220 uf electrolytic (C14,32,33,35) Controls and Hardware 1 Printed circuit board 3 10K ohm potentiometer (R1,R2,R3) 1 DPDT push switch (S1) 1 PC mount RCA jack (J1) 1 PC mount subminiature speaker jack (J2) 1 9-volt battery bracket (B1) 1 9-volt battery snap-on clip REQUIRED, NOT SUPPLIED 1 9-volt alkaline battery 1 VHF antenna with cable terminated in RCA-style plug or adapter 1 Speaker or headphones FR-220 · 7 FR220 BLOCK DIAGRAM U1 SA602 MIXER U2, 3359 FR-220 · 8 FR220 PARTS LAYOUT DIAGRAM FR-220 · 9 NOTE CONCERNING THE AUDIO OUTPUT JACK Your receiver kit is supplied with a standard subminiature 2.5 mm (3/32") audio jack, which mates with commonly available earphone plugs and adapters available at Radio Shack, such as 274-290 (plug) or 274-327 (adapter for 1/8" mono plug). If you prefer to use another size and style jack, we suggest that you still install the original jack and then wire your own jack in parallel with it rather than rough up the PC board to accommodate your jack. SEMICONDUCTOR REPLACEMENT DATA U1 SA602 U2 MC3359 (Motorola) U3 LM386 (National) Q1 2SC2498 or 2570 Q2,3 2N3904 D1 BB405 D2 1N4148 Contact Ramsey Factory ECG860 or SK7731 available at Radio Shack, other suppliers ECG10 or SK9139 available at Radio Shack, other suppliers contact Ramsey Factory available at Radio Shack, other suppliers FR-220 · 10 RAMSEY "Learn-As-You-Build" KIT ASSEMBLY: We have a twofold "strategy" for the order of the following kit assembly steps. First, we install parts in physical relationship to each other, so there's minimal chance of inserting wires into wrong holes. Second, whenever possible, we install in an order that fits our "Learn-As-You Build" Kit building philosophy. FOR EACH PART, OUR WORD "INSTALL" ALWAYS MEANS THESE STEPS: 1. Pick the CORRECT part value to start with. 2. Insert it into the CORRECT PC board location. 3. ORIENT it correctly, which means: PLEASE follow the PC board drawing and the written directions for ALL parts where there's a right way AND a wrong way to solder it in. (Diode bands, electrolytic capacitor polarity, transistor shapes, dotted or notched ends of IC's, and so forth.) 4. Solder ALL connections unless directed otherwise. Use enough heat and solder flow for clean, shiny, completed connections. Don't be afraid of ANY pen-style soldering iron having enough heat to damage a component. 5. Trim or "nip" excess wire lengths after soldering. NOTE: Save some of the longer wire scraps nipped from resistors and capacitors. These will be used to form wire jumpers (JMP1, etc.) to be soldered in just like parts during these construction steps. Now, let's start building! 1. Press S1 firmly into its six holes and solder all six pins. The switch fits the board only one way. Ignore the other set of six solder connectors on the switch. 2. Install J1, the RCA-style antenna jack. Solder all 4 points. 3. Install J2, the subminiature phone jack. Solder all three points. Be gentle and patient in inserting, so as not to damage the solder tabs. 4. Install controls R1, R2 and R3. Insert the three PC mounted controls into their positions. Check that the controls are pressed in firmly and straight against the top of the board. Solder the three center pins and then the two larger mechanical mounting tabs. Use enough solder for a solid connection. FR-220 · 11 Also, if you plan to use an enclosure other than the custom Ramsey enclosure and knob kit, you may wish to locate ...