6 METER FM RECEIVER KIT
Ramsey Electronics Model No. |
FR6 |
Check out the 6 meter action with this simple and fun to build FM receiver. Receive crystal-clear signals from thousands of miles away! Six meters is a fascinating band! Tune the entire 6 Meter band or the VHF low Police and Fire band.
•Tunes any 5 MHz portion of the 40 to 60 MHz band.
•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 instructions carefully guide you to a finished kit that works the FIRST time!
RAMSEY TRANSMITTER KITS
·FM100B Professional FM Stereo Transmitter
·FM25B Synthesized Stereo Transmitter
·AM1, AM25 AM Transmitters
· TV6 Television Transmitter
RAMSEY RECEIVER KITS
· FR1 FM Broadcast Receiver
· AR1 Aircraft Band Receiver
· SR2 Shortwave Receiver
·AA7 Active Antenna
·SC1 Shortwave Converter
RAMSEY HOBBY KITS
·SG7 Personal Speed Radar
·SS70A Speech Scrambler
· SP1 Speakerphone
·WCT20 Wizard Cable Tracer ·ECG1 Heart Monitor
·LABC1 Lead Acid Battery Charger ·IG7 Ion Generator
·CT255 Compu Temp Digital Binary Thermometer
·LC1 Inductance-Capacitance Meter
RAMSEY AMATEUR RADIO KITS
·HR Series HF All Mode Receivers
·QRP Series HF CW Transmitters
·DDF1 Doppler Direction Finder
·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.
FR-10 10 METER FM RECEIVER KIT INSTRUCTION MANUAL Ramsey Electronics publication NO. MFR6 Rev. E1
First printing: January 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.
FR6 • 2
Ramsey Publication No. MFR6
Price $5.00
KIT ASSEMBLY |
AND INSTRUCTION MANUAL FOR |
FR6 6 METER
FM RECEIVER KIT
TABLE OF CONTENTS |
|
Introduction to the FR6.................. |
4 |
Circuit Description ......................... |
5 |
Parts List........................................ |
6 |
Simplified Block Diagram .............. |
8 |
Parts Layout Diagram.................... |
9 |
Schematic Diagram....................... |
10 |
FR6 Assembly Instructions ........... |
11 |
Testing and Alignment................... |
18 |
Enclosure Ideas............................. |
20 |
Troubleshooting Guide.................. |
21 |
Notes for Advanced Users ............ |
22 |
Ramsey Kit Warranty .................... |
23 |
FR6 • 3
INTRODUCTION
FM and repeaters on 6 meters? You bet!
There's not a lot to say about using the FR6 receiver once its been correctly built and aligned. If 6 meters is "dead”, it resembles the usual 2 meter action. If 6 meters is "hot", you’ll find an amazing variety of crystal-clear FM signals from many thousands of miles away! If there are local 6 meter repeaters in your area, the FR6 will be just as active as the local repeater gang.
Since the FR6 “hears” only FM, the various SSB and CW signals on the band will not be properly demodulated as to be intelligible.
This receiver is a good project for amateurs wishing to become more familiar with 6 meter FM before choosing a transceiver, or for those active on 6 who want an inexpensive receiver to take on trips, keep in a briefcase or to watch for band openings.
Most Ramsey Electronic Kits 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 FR6 FM Receiver is best regarded as a "Skill Level 2" project, (or least Level 1.46!) 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 that Six Meters 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 HR40 Forty Meter receiver before assembling the FR6, but we are confident that you can construct the FR6 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 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.
FR6 • 4
BUILDING YOUR FR6 KIT
There are just over 200 solder connections on the FR6 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.
FR6 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 (8-pin DIP) mixerproduct detector-oscillator. The tuneable 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 50-54 MHz signals, the oscillator must tune 60.7 to 64.7 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.
The MC3359 IC has an internal oscillator controlled by the 10.24 MHz crystal. The 10.24 MHz signal is mixed with the 10.7 MHz input from U1 to convert down to the low IF of 450 KHz. The 450 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
FR6 • 5
practical level for speaker or headphone operation. Pin 16 of U2 will ground the input of U3 when the squelch is closed.
L4, a 450 KHz IF coil, permits adjustment of the 90-degree voltage-current phasing ("quadrature") of FL2's output to the FM detector demodulator (pin 8 of the MC3359).
PARTS LIST
Inductors
2 .15 uH inductors [looks like a resistor with brown-green-silver bands] (L1,L2)
1 slug-tuned turn coil [blue color] (L3)
1 shielded transformer coil [marked LB 53303] (L4)
Semiconductors and IC's
1 2SC2498 or 2SC2570A transistor (Q1)
3 2N3904 transistor (Q2,Q3,Q4)
1 SA602 8-pin IC (U1)
1 MC3359 18-pin FM receiver IC (U2)
1 LM386 8-pin audio amplifier IC (U3)
1 Varactor diode, BB505 [orange body marked BB505] (D1)
1 1N4148 signal diode (D2)
Special Components
1 10.24 MHz Crystal (Y1)
1 10.7 MHz ceramic filter [brown, molded, 3 leads] (FL1)
1 450 KHz ceramic filter [black, square] (FL2)
Fixed Resistors
1 2 ohm [red-black-gold] (R22)
3 270 ohm [red-violet-brown] (R6,9,20)
1 470 ohm [yellow-violet-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-violet-orange] (R4,8,13,21)
1 100K ohm [brown-black-yellow] (R16)
1 470K ohm [yellow-violet-yellow] (R15)
1 1 megohm [brown-black-green] (R10)
Capacitors
1 4.7 or 5 pF (C2)
2 10 pF (C1,5)
1 22 pF (C19)
FR6 • 6
4 62 pF (C3,4,9,10)
4 100 pF [marked 100, 101, or 101K] (C6,11,12,22)
1 220 pF [marked 220 or 221] (C18)
6 .001 uF [marked .001 or 102 or 1 nF] (C7,8,20,23,24,25)
8 .01 uF [marked .01 or 103 or 10 nF] (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
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
NOTE CONCERNING THE AUDIO OUTPUT JACK
Your receiver kit is supplied with a standard subminiature 2.5 mm (3/32") audio output 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 to rough up the PC board to accommodate your jack.
FR6 • 7
FR6 BLOCK DIAGRAM
U2, 3359 |
FR6 • 8
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