2 METER AMATEUR PLL SYNTHESIZED FM TRANSCEIVER 140 - 180MHz Ramsey Electronics Model No.
A DEDICATION The Ramsey FX-series FM Transceiver Kits are writing a truly NEW chapter in the annals of the ham radio story. Growing numbers of today's radio amateurs ARE willing to build, understand, adjust and maintain modern VHF gear capable of digital frequency programming and data communication as well as FM voice. How do we know? We know it because, during 1991, thousands of hams worldwide built and are using our pioneering FTR-146 for two meters.
TABLE OF CONTENTS: The Ramsey FX-146 Tranceiver Manual is organized into three sections: General Reference Information, Kit Assembly Phase 1, and Kit Assembly Phase 2. FX-146 GENERAL REFERENCE INFORMATION Notice Regarding FX-146 Frequency Coverage ................................4 FX-146 Technical Specifications ........................................................5 Introduction to Transceiver Kit Assembly ...........................................6 A Message to Ham Radio Beginners .....................
IMPORTANT NOTICE The Ramsey FX-146 VHF FM Transceiver is capable of TRANSMITTING as well as receiving on any frequency in the range of 140 to 180 MHz, making it suitable for a wide range of VHF communications requirements. Operation of the Transmit function of this equipment requires an appropriate license issued by the Federal Communications Commission (FCC) for the class of operation intended.
SPECIFICATIONS FOR THE RAMSEY FX-146 General: Frequency Range: Any 20 MHz segment between 140 and 180 MHz Tuning: Diode-programmable PLL synthesis 12 front panel selected frequency pairs, easily expandable by switches, microprocessors, computers, etc. Programming: 5 KHz steps with programmable offsets Transmit Offset: Programmable: Simplex, +1.2, -1.2, Aux Mode: NBFM Packet (Data) Operation: All rates incl. 9600 baud .
INTRODUCTION to FX-series VHF Transceiver Kit Assembly For the 1990's, Ramsey Electronics has adopted a "Learn As You Build" philosophy for ALL our electronics kits. We feel that licensed ham operators should know about the equipment they use, and also should have the desire to understand how their gear works. Additionally, it has been our corporate response to all those urgings by public officials that both students and their parents need to become sharper in science and math.
parts as a finished product! For a minimal investment of your time as well as your well-earned money, you will have a VHF FM voice-data transceiver that you will truly own. Real "owning" ultimately means knowing how to maintain and understand something that we have, in contrast to merely possessing a thing because you spent the bucks to do so. You'll have the flexibility of 12 channels chosen by YOU with the easy ability to change or expand. You'll have both FM voice and high-speed data capability.
A MESSAGE TO HAM RADIO BEGINNERS: If you have just earned your Novice or Technician license, or are studying for either of them right now, we'd like to say a special Thank You for choosing this Ramsey VHF/UHF transceiver as part of your ham radio beginnings. We have tried to make this instruction manual as clear as possible. However, there are some VHF radio "basics" covered by the FCC question pools for all ham license study guides that we must presume that you have studied and understood.
DC POWER SUPPLY CONSIDERATIONS : Your Ramsey FM Transceiver is designed to operate from any stable DC voltage source in the 12 to 15 volt range, from typical car, boat or plane 12V systems to a wide variety of battery packs or AC-powered DC sources. In a pinch, you can get on the air for quite a while with 8 to 10 ordinary "D" cells! Our lab tests show only a .93 amp current draw for 5 watts of RF output. We have just a few points of advice and caution: 1.
ENCLOSURE & HARDWARE CONSIDERATIONS: The companion CFX case and knob kit is sold as a separate option ONLY as an accommodation to those radio hams who have their own ideas or resources for the "finishing touches." However, a proper case for your FX-series is much more than a "finishing touch," since the controls and jacks are panel mounted and proper RF shielding is required. The CFX case measures 9-3/4"L X 6"W X 1.5"H. 9" x 6" dimensions are minimum for accommodating the PC board.
Quantity RS Part No. Description 1992 Price ($) 1 270-272/74 Deluxe Project Enclosure 8.79 or 10.79 1 set 274-section Pkg. of 3 or 4 knobs 2.00-3.00 1 set 270-201 Rub-on project labels 2.99 2 sets 276-195 PC-board standoffs/ 2.38 This $16 to $18 (plus tax) in basic hardware also presumes availability of all needed drill bits and/or a reamer or punches of sufficient size to make the needed access holes for the rear panel jacks.
THE RAMSEY CFX TRANSCEIVER ENCLOSURE KIT: The CFX Kit is very obviously a fair value and solid investment for the long term performance and worth of your transceiver. As we have mentioned, we make it "optional" ONLY because some of our ham customers have specialized applications requiring only the basic PC board kit. We try whenever we can to accommodate that important do-it-yourself spirit of ham radio.
resoldered after passing through the grommet. Snap in the locking section of the relief grommet only AFTER both the red and black wires are in place. 4. Remove the two screws from the SO-239 antenna connector, gently bend the lugs as needed to match the rear panel holes, then secure the jack and lugs to the rear panel. 5. Since the top shell will not be needed until you're ready to go on the air, keep it wrapped in protective material until you're really ready to use it. 6.
GUIDE TO PC BOARD I/O CONNECTIONS: In addition to primary interconnections required for jacks and controls, etc., your FX-series Transceiver PC board provides additional access to operating voltages and circuit features to make later customizing as neat and easy as possible.
1. PRIMARY CONNECTIONS: PWR (near L20): +12-15 volts DC from S1. GROUND: - DC from battery or power supply. SPEAKER: both connections near C37 MIKE: both connections (IN & GND) near notched end of U1. SQUELCH: two connections marked CW and W near C18 VOLUME: three connections marked IN, OUT, GND. ANTENNA: Center of SO-239 connected at "RF OUT" near C71. CHANNEL SWITCH: Row of holes numbered 1 through 12. The switch wiper (moving contact) is wired to +5V near "1.
MICROPHONE & SPEAKER INFORMATION The FX transceivers with the hardware supplied are designed to accept standard ICOM or ICOM-compatible speaker-mikes such as MFJ-284. The most conveniently available such unit is Radio Shack No.19-310. Be aware that the receiver audio amplifier is capable of supplying a husky 2 watts or more of audio power and will drive full-size communications speakers to excellent volume levels. The PTT switching circuit can be activated simply by introducing a resistance (e.g.
VHF PACKET DATA OPERATION Your FM transceiver was planned and designed to accommodate easy and reliable VHF packet radio operation. The J1 Packet I/O port can be quickly connected to many modern TNC's and the Ramsey P-IBM or P64 Packet Modems with Radio Shack's shielded DIN cable (42-2151). Otherwise, your first step is to prepare a reliable 5conductor cable with a 5-pin DIN plug (RS 274-003) at one end, and the correct connector needed by your packet TNC at the other end.
RAMSEY FX-SERIES FM TRANSCEIVER (With emphasis on the PLL and VCO) MC13135 FX 146 • 18
FX-146 CIRCUIT OVERVIEW The FX-146 VHF FM Transceiver circuit theory is explained in progressive stages and in some detail as part of our "Learn As You Build" approach to electronic kits. Builders are encouraged to study and learn about a stage or section, build it and then test it before going to the next stage. The circuit explanations are necessarily written for people with all levels of experience, starting with and FAVORING beginners.
FX 146 • 20
Stage CR: Integrated FM Receiver The MC13135 is a complete FM narrowband receiver from antenna input (pin 22) to audio output (pin 17). The low voltage dual conversion design results in low power drain, excellent sensitivity and good image rejection in narrowband voice and data link applications. The FX146 implementation of this IC yields increased image rejection by using a 21.4 MHz first IF rather than the traditional 10.7 MHz.A precision 2-pole crystal filter (FL1) is used for the 21.4 MHz first IF.
connection as well as +DC, D6 is grounded through RF choke L17, which prevents the antenna RF from being shorted to ground. During Transmit, D7 passes RF from the transmitter to the antenna, and L17 again prevents loss of RF to ground. During transmit, D6 is blocking transmitter RF from the receiver circuit. For maximum protection of the more delicate receiver circuit, D2 is turned on during transmit to ground any stray RF.
thereby increasing available modulation voltage. The VCO requires a very pure source of well-filtered DC, free of AC hum, alternator whine or other disturbance. R19 and the 47 uf C40 form a basic low pass filter. Transistor Q4 serves as an electronic capacitance multiplier. The actual effect of the filter is that the beta of Q4 multiplies the 47 uf for a virtual capacitance effect of a much larger device.
FREQ. N= BINARY PROGRAMMING VALUES 144.000 28,800 0111 0000 1000 0000 148.000 29,600 0111 0011 1010 0000 R48 and C85 form yet another low pass filter to ensure that any 5 KHz "whine" will not get into the VCO. Because the DC charge developed in C85 (.1 uf) would slow down the PLL during major frequency swings, such as just going from transmit to receive, D8 and D10 are set up back-to-back across voltage dropping R48.
There are several methods for quickly finding the required binary code for a particular frequency and its "N" number: 1. Descending Subtraction (see Programming Worksheet) 2. Printed reference lists (see Popular 2 Meter Frequency Pairs) 3.
Stage M: Microphone Amplifier and PTT Circuit U4 is a LM324 quad op amp: two are used as a conventional microphone gain amplifier, and the other two are used in the PTT (push to talk) circuit. Capacitor C83 couples microphone audio to U4A and isolates the audio (AC) from the PTT circuitry (DC). U4 is powered by a single +8V supply through the use of a voltage divider network (R59, R40). The gain of the amplifier is established by the ratio of R56 to R58. A passive low pass filter is formed by R51 and C89.
Using the FX-series FM Transceiver Quick Reference Programming Guide: In addition to "pencil & paper math" calculation directions and also a handy computer BASIC program for programming the FX- series Transceiver for any frequency and transmit offset within its specified range, we provide this guide for binary programming of a variety of popular Repeater frequency pairs as well as some other frequencies of general interest.
FX-146 Quick Program Reference Standard 2 Meter band repeater pairs and selected frequencies Program as follows: 1. Install diodes at 16K, 8K, 4K and NO diodes at 32K, 2K ,1K positions. 2. PLUS install diodes at 512 through 1 positions as needed per this Quick Reference Chart. 3. For repeater channels, add the proper repeater TX offset diode. Simplex channels: add the 'SIMP' diode. 4. A '1' means to install a diode, '0' means NO diode. Freq Offset N 512 256 128 64 32 16 8 4 2 1 145.
145.49 - 29,098 0 1 1 0 1 0 1 0 1 0 146.61 - 29,322 1 0 1 0 0 0 1 0 1 0 146.64 - 29,328 1 0 1 0 0 1 0 0 0 0 146.67 - 29,334 1 0 1 0 0 1 0 1 1 0 146.70 - 29,340 1 0 1 0 0 1 1 1 0 0 146.73 - 1 0 1 0 1 0 0 0 1 0 146.76 - 29,352 1 0 1 0 1 0 1 0 0 0 146.79 - 29,358 1 0 1 0 1 0 1 1 1 0 146.82 - 29,364 1 0 1 0 1 1 0 1 0 0 146.85 - 29,370 1 0 1 0 1 1 1 0 1 0 146.
N = Frequency (KHz) ÷ 5 Freq = Receive frequency/Repeater output 145.01 S 29,002 0 1 0 1 0 0 1 0 1 0 145.03 S 29,006 0 1 0 1 0 0 1 1 1 0 145.05 S 29,010 0 1 0 1 0 1 0 0 1 0 145.07 S 29,014 0 1 0 1 0 1 0 1 1 0 145.09 S 29,018 0 1 0 1 0 1 1 0 1 0 145.01 - 29,002 1 0 1 0 0 0 1 1 0 1 145.03 - 29,006 1 0 1 0 0 1 0 1 1 1 145.05 - 29,010 1 0 1 0 0 1 1 0 1 1 145.07 - 29,014 1 0 1 0 1 1 0 0 0 1 145.
Let's try doing an example. We want to receive 146.
+RPT or -RPT positions. Using Computer BASIC as a Diode Matrix Programming Aid The purpose of the following BASIC program is to be as CLEAR AND GENERIC as possible with no concern for programming efficiency or sophistication. Those who enjoy and understand programming in Basic can dress it up to suit themselves. Or, they can write a program that satisfies their own standards. A major purpose of the deliberate simplicity is that the routine should run on virtually any computer using any version of Basic.
50 52 55 60 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 200 205 206 210 215 216 220 225 226 230 235 236 240 245 246 250 255 256 260 265 266 270 275 276 280 285 286 290 295 296 300 305 306 310 315 316 320 325 PRINT “Enter Receiver Frequency as 6 digits with NO decimal!” INPUT “For example: 146520.
326 330 335 336 340 345 346 347 400 405 410 415 420 425 430 435 440 445 450 455 460 465 470 475 IF NL < 8 THEN NM = NL IF NM => 4 THEN NN = 1 IF NM > 4 THEN NX = NM - 4 IF NM < 4 THEN NX = NM IF NX > 2 THEN OO = 1 IF NN = 2 THEN OO = 1 IF NX = 3 THEN PP = 1 IF NX = 1 THEN PP = 1 PRINT “32768 - “; AA PRINT “16384 - ”; BB PRINT “ 8192 - “; CC PRINT “ 4096 - “; DD PRINT “ 2048 - “; EE PRINT “ 1024 - “; FF PRINT “ 512 - “; GG PRINT “ 256 - “; HH PRINT “ 128 - “; II PRINT “ 64 - “; JJ PRINT “ 32 - “; KK PRINT “
0 1 1 1 0 0 1 0 1 0 1 1 1 1 0 1 >>> Enter Next Frequency for Programming: Enter Receiver Frequency as 6 digits with NO decimal! For example: 146.52 MHz. = 146520. Enter here >>> ? HOW TO ACTIVATE AN AUXILIARY OFFSET: 1. Install NO diode in SIMP, -RPT or +RPT for the channel that gets a nonstandard offset. 2. Program the AUX matrix row for the desired offset, following our published instructions. 3. Connect the channel row to the AUX matrix row by installing a diode as shown below.
PROGRAMMING THE 'MINUS' OFFSETS We showed the Plus offsets first to prepare you for the Minus offsets. The offsets are entered into the FX synthesizer through the binary adders, U710. Notice that we said adders and not subtractors; in binary there is 'no such animal' as a subtractor. We must use the technique known as 'two's complement addition' which actually performs a subtraction process! This may sound complicated, but it really isn't.
EXAMPLE 2: RECEIVER OSCILLATOR FREQUENCY We know from previous circuit discussion that the PLL synthesizer must run 21.4 MHz lower when in receive mode. Two things must be done to do this; first, we switch out varactor diode D3 to allow the VCO L-C circuitry to tune 21.4 MHz lower, and secondly, program in a 'minus' 21.4 MHz offset to the synthesizer. This offset is permanently programmed into the matrix because the 21.4 MHz 1st IF is integral to the FX receiver design.
FX-146 PROGRAMMING SUMMARY Programming your FX-146 is really quite simple; all it takes is a clear mind, a scratch pad and a calculator. In closing, let's find the proper N value for a common NOAA weather channel, 162.55 MHz.
FX-XCVR RIBBON CABLE 1N914/ PC BOARD 1N4148 CONNECTION SWITCH: SPST 1 2 4. DON'T run switching cables across the VCO and Transmit RF side of the PC board. 5. Please DO submit successful frequency control ideas as articles for your favorite ham radio magazine. Your pay as author may cover the cost of your transceiver! 4 8 16 32 6. Please DO mail or fax us your good ideas. 64 7. Please DON'T try out ANY modifications of the basic FXTransceiver unless you already have it WORKING fine.
FX-SERIES TRANSCEIVER GLOSSARY The following is a deliberately INFORMAL collection of: • Technical terms useful to know in understanding your FX- transceiver design. • Acronyms (phrases expressed by first letters of words: example: PLL = Phased Locked Loop) • Selected Electronics Industry "jargon" Any of these words or expressions might be used in this instruction manual or in conversation related to your FX- transceiver, either with other hams or with Ramsey technicians.
CCW = see CW below. COR = "Carrier Operated Relay," a switching circuit activated by the detection of a carrier signal in a receiving circuit. "CW" = TWO common meanings in electronics: "Continuous Wave" for the communicating of Morse code signals, or "Clockwise" to designate a point on a variable control. "CCW" therefore means "counterclockwise.
elements connected to RF ground, the horizontal elements are called a "groundplane." HIGH = In solid-state circuitry, to say a given device pin or circuit point is at a "logic high" is to say that it shows a + DC supply voltage at that point. Switching to the opposite state (LOW) or back again for some specific purpose is a fundamental capability of the circuit. HOUSE-NUMBER = A manufacturer's part number different from the industry-standard description of a part.
magic number (decimal) to understand in FX binary frequency programming. N = the frequency in KHz divided by 5 KHz. NBFM = "Narrow-Band FM." NE- = prefix to transistors or IC's made by Signetics, Inc. OFFSET = The distance in KHz or MHz of the transmitted signal from the primary or received signal. The "TX Offset" may be higher or lower, depending on the repeater setup or other application.
controlled, compared with another frequency, as is done in a PLL circuit. See PHASE DETECTOR, PLL. RSSI = "Received Signal Strength Indicator," a function of the MC13135 IC and comparable circuits which permits MEASURING of the relative strength of a received signal. A few microamps of variation can be interpreted as DB (decibels) of signal strength. RX = Abbreviation for receive, receiver, receiving.
amount of DC voltage applied to it. The higher the voltage, the lower the capacitance. See also VCO. VCO = "Voltage Controlled Oscillator," an oscillator whose frequency is varied by DC voltage applied to varactor diodes, which change capacitance in step with the voltage level. ZENER DIODE = a diode designed to have a very specific reverse breakdown voltage. This property makes the Zener diode ideal for simple voltage regulators or precise voltage drop elements.
FX- TROUBLESHOOTING GUIDE The FX- transceiver is designed to W-O-R-K with a minimum of adjustment or alignment. By imprinting the location and correct orientation of each component on the PC-board itself in addition to publishing detailed assembly steps, we have virtually guaranteed the successful operation of your transceiver from the moment you turn on the switch. A detailed guide to servicing a transceiver requiring so few internal adjustments is virtually pointless to compile.
despite the detail of our explanations, be sure you set one channel up for 146.52 MHz Simplex before you pursue troubleshooting. It is very important to have a clear understanding of how to program the frequency synthesizer and offset matrixes of your transceiver. It's fairly easy to double-check "obvious" details such as IC orientation, diode polarity, electrolytic capacitor polarity, and those other construction essentials that we stress repeatedly.
NOTE ON REPLACEMENT PARTS: If you lose or damage parts during assembly or testing, you may, of course, order any needed replacement parts by writing or faxing the Ramsey Electronics, Inc. factory. Some of the more common parts may also be picked up at Radio Shack or other local parts distributors. Use EXACT values when replacing parts.
D11,D12 6.2 V Zener RS276-561 VR1 7808 ECG964, SK3630 or RE VR2 7805 RS276-1770 U1 MC13135 RE or Motorola U2 LM380 ECG740A, SK3328 or RE U3 MC12017 RE or Motorola U4 LM324 RS276-1711 U5 LM358 ECG928, SK3691 or RE U6 MC145152 RE or Motorola FX-146 MASTER COMPONENT INDEX The following pages were prepared to serve these purposes: 1. A general cross-reference for circuit study and servicing; 2. Additional help for parts sorting and identification; 3.
G: H: M: TC: TX: PART PLL Frequency Synthesizer Diode Matrix, Frequency Programming Microphone Amplifier and PTT Transmit Coil and RF Choke Preparation Transmit Buffer, Driver and RF Final VALUE or ID STEP [ ] [ ] C1 .001 A16 [ ] [ ] C2 .001 A13 [ ] [ ] C3 .001 A14 [ ] [ ] C4 .001 A15 [ ] [ ] C5 .01 CR9 [ ] [ ] C6 .1 CR15 [ ] [ ] C7 4.7 or 10 uF CR16 [ ] [ ] C8 .1 CR11 [ ] [ ] C9 4.7 or 10 uF CR10 [ ] [ ] C10 .001 CR19 [ ] [ ] C11 .
[ ] [ ] C24 .001 M16 [ ] [ ] C25 100 pF DR6 [ ] [ ] C26 .01 CR14 [ ] [ ] C27 8.2 pf DR8 [ ] [ ] C28 47 pf DR19 [ ] [ ] C29 330 uF electrolytic B7 [ ] [ ] C30 47 pf DR17 [ ] [ ] C31 47 pf DR22 [ ] [ ] C32 100 pf F13 [ ] [ ] C33 .01 B4 [ ] [ ] C34 470 uF B6 [ ] [ ] C35 100 pf F18 [ ] [ ] C36 .01 E12 [ ] [ ] C37 .01 B8 [ ] [ ] C38 .001 F11 [ ] [ ] C39 .001 E14 [ ] [ ] C40 47 uF elec. E13a [ ] [ ] C41 .1 B5 [ ] [ ] C42 1500 uf elec.
[ ] [ ] C53 .01 D10 [ ] [ ] C54 56 pf E3 [ ] [ ] C55 .01 TX30 [ ] [ ] C56 10 pf TX5 [ ] [ ] C57 .001 F12 [ ] [ ] C58 .1 uf TX26 [ ] [ ] C59 .001 TX27 [ ] [ ] C60 220 uf elec. TX25 [ ] [ ] C61 .001 TX17 [ ] [ ] C62 .001 M37 [ ] [ ] C63 .01 TX43 [ ] [ ] C64 .001 TX33 [ ] [ ] C65 .1 uf A17 [ ] [ ] C66 3.9 pf TX18 [ ] [ ] C67 2.2 uf elec. G11 [ ] [ ] C68 .01 G23 [ ] [ ] C69 .01 G22 [ ] [ ] C70 2.2 uf elec.
[ ] [ ] C82 10 pf TX10 [ ] [ ] C83 .001 M2 [ ] [ ] C84 35 pf trimmer TX32 TX final output tuning [ ] [ ] C85 .1 uf G38 PLL loop filter [ ] [ ] C86 .001 M1 [ ] [ ] C87 39 pf G4 [ ] [ ] C88 .001 M3 [ ] [ ] C89 .001 M15 [ ] [ ] C90 2.2 uf elec. G13 [ ] [ ] C91 .01 G24 [ ] [ ] C92 2.2 uf elec. G14 [ ] [ ] C93 4.7 or 10 uf elec. M14 [ ] [ ] C94 3.9pf F19 [ ] [ ] C95 4.7 or 10 uf elec. A6 [ ] [ ] C96 4.7 or 10 uf elec. G12 [ ] [ ] C97 .
[ ] [ ] D7 BA482 PIN M34b See T-R switch theory [ ] [ ] D8 1N914 or 1N4148 G34 works with D10,C85: see PLL theory [ ] [ ] D9 1N914 or 1N4148 A18 [ ] [ ] D10 1N914 or 1N4148 G35 see D8 [ ] [ ] D11 1N914 or 1N4148 M31 assures positive switching by U4D [ ] [ ] D12 1N914 or 1N4148 M32 " [ ] [ ] D13 1N914 or 1N4148 H8a disables -RPT during receive [ ] [ ] D14 1N914 or 1N4148 H8b turns on Q15 during receive [ ] [ ] D15 1N914 or 1N4148 H7 disables +RPT during receive [ ] [ ] D16
L: INDUCTORS (Coils, Transformers, Chokes): [ ] [ ] L1 455 KHz LB53303HK CR23 FM quadrature adjust [ ] [ ] L2 .015 uH DR20 Q2 input bandpass filter [ ] [ ] L3 not used [ ] [ ] L4 not used [ ] [ ] L5 .015 uH DR18 [ ] [ ] L6 .015 uH DR21 [ ] [ ] L7 variable coil E1 [ ] [ ] L8 2.2 uH TX34 [ ] [ ] L9 VK200 RF choke TX49 Install AFTER alignment! [ ] [ ] L10 .04 uH TX47 Install AFTER alignment! [ ] [ ] L11 .33 uH, mini TX7 [ ] [ ] L12 2.5 T TX40 [ ] [ ] L13 1.5T, 5/16" dia.
[ ] [ ] Q5 2SC2498 NPN RF F8 VCO common base buffer [ ] [ ] Q6 2N3904 NPN B9 Carrier detect switch [ ] [ ] Q7 2SC2498 NPN RF E9 VCO [ ] [ ] Q8 SD1127 or MRF237 TX2 Transmit final amplifier [ ] [ ] Q9 2N3866 NPN RF TX1 Transmit driver [ ] [ ] Q10 NE021 TX14 Transmit buffer [ ] [ ] Q11 2N3904 M18 Grounds mic amp in receive [ ] [ ] Q12 PNP 2N3906 (228256) M20 PTT switching [ ] [ ] Q13 PNP 2N3906 (228256) M21 +8R PTT output [ ] [ ] Q14 PNP 2N3906 (228256) M22 +8T PTT outpu
[ ] [ ] R16 47K DR13 [ ] [ ] R17 470 ohm DR14 [ ] [ ] R18 270 ohm E7 [ ] [ ] R19 10K E13b [ ] [ ] R20 270 F5 [ ] [ ] R21 470 M33 [ ] [ ] R22 10K E6 [ ] [ ] R23 100 ohm F6 [ ] [ ] R24 10K CR5 [ ] [ ] R25 47K E18 [ ] [ ] R26 51 ohm F3 [ ] [ ] R27 47K F4 [ ] [ ] R28 470 ohm DR5 [ ] [ ] R29 100 ohm TX6 [ ] [ ] R30 51 ohm E5 [ ] [ ] R31 47K M39 [ ] [ ] R32 82 (1/2W) TX48 [ ] [ ] R33 47K M40 [ ] [ ] R34 270 ohm TX13 [ ] [ ] R35 100K E20 [ ] [ ] R36 10K
[ ] [ ] R43 10K G26 [ ] [ ] R44 22K G20 [ ] [ ] R45 82 ohm 1/2W TX23 [ ] [ ] R46 10K trimpot M19 [ ] [ ] R47 10K G31 [ ] [ ] R48 10K G33 [ ] [ ] R49 10K M9b [ ] [ ] R50 10K M9a [ ] [ ] R51 47K M10 [ ] [ ] R52 10K G27 [ ] [ ] R53 22K G21 [ ] [ ] R54 200 or 220 (1/2W) DR3 [ ] [ ] R55 10K G19 [ ] [ ] R56 47K M11 [ ] [ ] R57 2.2K M6 [ ] [ ] R58 270 ohm M8 [ ] [ ] R59 100K M7 [ ] [ ] R60 10K M23 [ ] [ ] R61 2.
[ ] [ ] R71 100K H22-H40 U6 counter input pulldowns [ ] [ ] R72 " " " [ ] [ ] R73 " " " [ ] [ ] R74 “ “ “ [ ] [ ] R77 " " " [ ] [ ] R78 " " " [ ] [ ] R79 " " " [ ] [ ] R80 " " " [ ] [ ] R81 " " " [ ] [ ] R82 " " " [ ] [ ] R83 " " " [ ] [ ] R84 " " " [ ] [ ] R85 " " " [ ] [ ] R86 " " " [ ] [ ] R87 " " " [ ] [ ] R88 " " " [ ] [ ] R89 " " " [ ] [ ] R90 10K G30 [ ] [ ] R91 100K H11-H21 U6 counter input pulldowns [ ] [ ] R92 " " " [ ]
[ ] [ ] R103 47K G28 [ ] [ ] R104 10K G29 [ ] [ ] R105 100 ohm F16 [ ] [ ] R106 10K F15 [ ] [ ] R107 10K M35 [ ] [ ] R108 2 ohm B3 [ ] [ ] R109 47K B10 [ ] [ ] R110 10K TX12 [ ] [ ] R111 4.7K M25 [ ] [ ] R112 4.
S: SWITCHES TP: TEST POINTS [ ] [ ] S1 on R7 (volume) A2 DC on-off [ ] [ ] S2 12 position "H" Frequency selection [ ] [ ] TP1 F20 VCO control voltage [ ] [ ] TP2 F20 VCO output frequency [ ] [ ] TP3 F20 U3 prescaler output U: INTEGRATED CIRCUITS [ ] [ ] U1 MC13135 CR1 FM dual-conversion receiver [ ] [ ] U2 LM380 B1 Receiver audio amplifier [ ] [ ] U3 MC12017 F21 Dual- modulus 64/65 prescaler [ ] [ ] U4 LM324 M17 Quad op amp: mic and PTT [ ] [ ] U5 LM358 G9 Dual op amp:
The RAMSEY FX Transceiver Kit WARRANTY Please read carefully BEFORE calling or writing in about your Kit. Most problems can be solved WITHOUT contacting the Factory! Notice that this is not a "fine print" warranty. We want you to understand your rights and ours too! All Ramsey kits will work if assembled properly. The very fact that your kit includes this manual is your assurance that a team of knowledgeable people have field-tested several "copies" of this kit straight from the Ramsey inventory.
KIT ASSEMBLY PHASE 1: Stage A: DC Power Regulation & Distribution Plus Packet Data I/O Connector Stage B: Receiver Audio Amplifier Stage CR: Integrated Circuit FM Receiver Stage DR: Receiver, Tuned RF Input and Preamp Stage E-F: Transceiver VCO with Buffer Stages Each set of Assembly Instructions is introduced by an explanation of how that part of the circuit works and what it is for.
FX-146 Transceiver Assembly Phase 1: Circuit stages A through E-F FX-146 MASTER PARTS LIST Before beginning assembly, take some time to check and organize these kit components in such a way that you can find them easily and not lose any or confuse them. Leave parts supplied on tape strips in the strips until you need them. The following headings also provide logical sorting categories.
CRYSTALS: 1 10.240 MHz, has 2 leads (Y2, PLL reference frequency) 1 21.855 MHz, has 2 leads (Y1, receiver IF oscillator) 1 21.4 MHz crystal filter, has 3 leads (FL1, 1st IF filter) INDUCTORS: 1 455 KHz shielded inductor, marked LB53303HK (L1) 1 Shielded variable coil, marked 8488 5-5 (L7) 4 .015 uH, 1.5 turns, .125" diameter (L2,5,6,14) 1 .04 uH, 4 turns, red color, (L10) 1 500 uH noise suppression choke, large with black shrink tubing over the body (L20) 2 .33 uh.
4 47 pf (C12,28,30,C31) 2 56 pf (C19,54) 10 100 pf (may be marked 100 or 101) (C17,20,22,25,32,35,45,46,47,50) ADDITIONAL DISC CAPACITORS: 22 .001 uf (may be marked .001, 102 or 1nf) (C1,2,3,4,10,23,24,38,39,43,44,52,57,59,61,62,64,77,83,86,88,89) 16 .01uf (may be marked .01, 103 or 10 nf) (C5,15,16,26,33,36,37,53,55,63,68,69,91,97,98,99) 8 .1 uf (may be marked .1 or 104) (C6,8,11,13,41,58,65,85) ELECTROLYTIC (Polarized) CAPACITORS: 4 2.2 uf electrolytic (C67,70,90,92) 8 4.
CONTROLS, HARDWARE AND MISC.: 1 volume control potentiometer with switch (may be any value from 10K to 100K) (R7,S1) 1 10K squelch control potentiometer (R13) 1 12-position rotary switch (S2) 1 3.5 mm. Jack, miniature (J2, speaker) 1 2.5 mm.
VERY IMPORTANT PC BOARD ASSEMBLY INFORMATION FOR A-L-L OUR BUILDERS! 1. Your FX- transceiver PC board is double-clad with plated- through holes. What this means in practice is that it is VERY important to select and install correct part values the FIRST time around. This type of board makes "desoldering" much more difficult and risky because the solder adheres inside the hole and flows to the component side of the board as well. It is VERY tricky to remove a part without damaging it.
at the factory have tried to help by grouping similar or related parts in individual sealed bags. Sorting organizers popular among kit builders include empty egg cartons, muffin tins, small box tops, or the corrugated edges of box cartons. Since the assembly of this kit is presented in distinct stages, some builders may prefer to group their parts by stage before beginning assembly. 11. HELPFUL HINT: Many of the parts are supplied on tape strips cut from bulk reels.
21. Use the extra spaces provided throughout this manual to write down the details of any changes or revisions noted on additional sheets that may be supplied with your kit. 22. You will be installing various wires for switches, controls and jacks very early in the assembly procedure. This is contrary to normal building or manufacturing practice but will permit progressive testing of completed stages.
STAGE A: DC POWER INPUT REGULATION & DISTRIBUTION and PACKET RADIO I/O CONNECTOR (J1) The "power supply" for your FX- transceiver is, basically, any "12-volt" battery or well designed power supply operating from 120VAC or other source. In theory, all "12V" sources should provide pure DC voltage to your FX- transceiver DC input.
STAGE A: DC POWER INPUT REGULATION & DISTRIBUTION and PACKET RADIO I/O CONNECTOR (J1) FX 146 • 72
Stage A: ASSEMBLY STEPS A1. Strip 1/8" of insulation from the heavier-gauge black wire, insert and solder in the GROUND hole. This connection may be soldered on the TOP side of the board as well as the solder side. A2. Strip 1/8" of insulation from the in-line fuse wire and solder it to one of the S1 switch lugs of the volume control (R7). The switch lugs are the two outermost lugs of the 5 lugs. FUSE VOLUME IN OUT A3.
A10. Study the PC board, locate the triangular set of 3 holes for VR2 (type 7805), and insert VR2 so that the flat metal tab side is toward the center of the board. Press VR2 in as far as it will go, solder and trim. A11. Near VR2, install C100, a 4.7 or 10 uf electrolytic, oriented for correct polarity. Stage A PROGRESS TEST: The power input circuitry is completed and can be tested before proceeding. Perform the test as follows: 1. Make sure a 1 amp fuse is installed in the fuse holder. 2.
A13. Install C2, .001 uf disc capacitor. It may be marked .001 or 1 nf or 102. (102 means a one, a zero and two zeros which equals: 1000 pf. 1000 pf is the same as .001 uf. This notation (102) is similar to the resistor color code to indicate resistance values. A14. Install C3, .001 uf. A15. Install C4, .001 uf. A16. Install C1, .001 uf (Don't confuse with C65). A17. Install C65, .1 uf. It may be marked .1 or 104. (As above, 104 means a one, a zero and four zeros = 100,000 pf which is the same as .
Stage B: Receiver Audio Amplifier The secret to the fine performance of the LM380 audio amplifier lies in careful selection and physical positioning of the several external components required to complete its circuit. The LM380 is a self contained general purpose audio amplifier capable of over 2 watts audio output with a voltage gain of 50. Audio from the FM discriminator (U1) is fed through C7 through the 10K volume control (R7) to pin 2, the amplifier input.
Stage B: Receiver Audio Amplifier and Speaker Connection Stage B: AUDIO AMPLIFIER CIRCUIT ASSEMBLY: Some of the Stage "A" steps required more detailed explanation than simply inserting and soldering parts. As we move along, there will be more and more short "one liners"! The following steps will complete a working audio amplifier ready to power up and test. B1. Install U2, the LM380 IC. Be sure to orient the dotted or banded end as illustrated.
B3. Install R108, 2 ohm (red-black-gold). B4. Install C33, .01 uf disc capcitor (marked .01 or 103). B5. Install C41, .1 uf disc capacitor (marked .1 or 104). B6. Install C34, 470 uf electrolytic. Watch out for correct polarity. B7. Similarly, install C29, 330 uf electrolytic. B8. Install C37, .01 uf disc capacitor (marked .01 or 103). B9. Install NPN transistor Q6.
Optional: To a test speaker, temporarily or to a speaker intended for regular use inside or along with your FX- Transceiver. B16. Solder the speaker cable to your choice of speaker. Give attention to the polarity marks on most bare speakers as well as enclosed units. The wire from the point marked SPKR should be connected to the speaker terminal marked (+). Stage B: AUDIO AMPLIFIER TEST: 1. Reconnect 12 volts DC as done for testing the power input circuit in stage A. (We assume speaker hookup per B15.) 2.
STAGE CR: FM RECEIVER CIRCUIT DUAL CONVERSION SUPERHET WITH IF FILTERS FX 146 • 80
Stage CR: Integrated FM RECEIVER (with Squelch Control) This step is named "CR" so that the assembly step numbers do not resemble designator numbers for capacitors. To fully appreciate the marvel of U1, the MC13135 FM Receiver IC, one would need to study the schematic diagram of any FM receiver more than 15-20 years old, including fully "solid-state" models. The MC13135 IC is truly a "Receiver-on-a-Chip.
"DR" of this project. The purpose of the "DR" circuitry is to filter out or at least diminish other signals while boosting signals in the 146 MHz region. 2. The First IF converts the incoming 146.52 MHz signal down to 21.4 MHz. In order to do this job, the IC's 1st IF Mixer needs ANOTHER frequency source to mix with the signal presented by the antenna through the filters and preamps of Stage DR. This other signal must be VERY precise since the mixer output is fed into a very sharp crystal filter at 21.
ADDITIONAL RECEIVER IC FUNCTIONS AND FEATURES In addition to audio output at pin 17, a separate high speed data output (up to 35000 baud) is available and may be linked directly to a packet TNC or other data controller using the jumper wire pad provided on the PC board. The MC13135 is capable of detecting true FSK (frequency shift keying) in addition to AFSK.
CR11. Install C8, .1 uf disc capacitor (marked .1 or 104). CR12. Install C13, .1 uf disc capacitor (marked .1 or 104). CR13. Install C14, 27 pf disc capacitor (marked 27). CR14. Install C26, .01 uf disc capacitor (marked .01 or 103). CR15. Install C6, .1 uf disc capacitor (marked .1 or 104). CR16. Install C7, 4.7 or 10 uf electrolytic. Watch polarity (or U1's audio won't reach U2!) The polarity doesn't always show up on the silkscreen so consult the pictorial for proper orientation. CR17. Install C13, .
CR29. Install FL1, the 21.4 MHz IF filter. Its 3 wires may be inserted either way; make sure its body is snug against the top of the board before soldering. CR30. Prepare three 8" lengths of hookup wire for connecting R13, the 100K Squelch Control. Strip back ¼" from one end of each wire. Tin all ends. • Select a wire, connect one stripped end to the three connecting lugs of the control. • Observe the diagram and locate the squelch wire connections on the printed circuit board.
frequency of the signal generator frequency plus 21.4 MHz. Because we have not yet constructed any of the input circuitry (Stage DR), you would also hear any signal on the signal generator frequency minus 21.4 MHz.
FX SERIES TRANSCEIVER Simplified Receiver Block Diagram ANTENNA LOW PASS FILTER HIGH PASS FILTER Q3 RECEIVE PRE-AMP BAND PASS FILTER 21.4 MHz FILTER, AMPLIFIER 21.885 MHz LOCAL OSCILLATOR SECOND IF MIXER LIMITER 6 POLE 455 KHz FILTER FM DISCRIMINATOR Q2 RECEIVE PRE-AMP FIRST IF MIXER PLL CONTROLLED VCO PROGRAMMED 21.
Stage DR: Receiver Tuned RF Input and Preamp FX 146 • 88
Stage DR: Antenna Input and RF Preamplifier The operation of the FM receiver IC was discussed in Stage CR. The purpose of the following circuitry is to minimize the strength of unwanted signals and to boost signals in the 140 - 160 MHz range before they reach the 1st mixer input of U1 (pin 22). In addition, the circuit includes PIN diodes for proper T-R (transmit-receive) switching.
STAGE DR ASSEMBLY: Be very attentive to capacitor values (in picofarads) and to coil descriptions throughout this section. DR1. Correctly identify and install PIN diode D6. It is the only BA479 used in the circuit, and its number is stamped plainly on the diode body. Be sure to orient the cathode end correctly! DR2. Install L17, 2.2 uH in upright position with the inductor's body in the designated hole. This is a molded inductor, resembling a resistor but is larger. Look for 2 red bands on its body. DR3.
Install the following resistors, each in upright position: DR13: R16, 47K ohm (yellow-violet-orange). DR14: R17, 470 ohm (yellow-violet-brown). DR15: R12, 100 ohm (brown-black-brown). DR16. Install C20, 100 pf. (marked 100 or 101). DR17. Install C30, 47 pf (marked 47). DR18. Install L5, .015 uH, a small 2 turn wire coil. DR19. Install C28, 47 pf (marked 47). DR20. Install L2, another .015 uH small 2 turn wire coil. DR21. Install L6, yet another 2 turn .015 uH coil. DR22. Install C31, 47 pf (marked 47).
Stages E - F: Transceiver VCO (Voltage Controlled Oscillator) and Buffer Stages FX 146 • 92
Stage E-F: The FX Transceiver VCO The VCO (Voltage Controlled Oscillator) provides basic frequency control for both transmit and receive modes. It is essential to understand its function in the transceiver circuit. Q7 is the oscillator transistor and the key VCO components are L7, D3 and D23. Think of the VCO for now as just a simple 'VFO' type RF oscillator whose output frequency can be changed by adjusting the slug in L7.
VCO CIRCUIT SUMMARY: The control voltage for the D3 and D23 varactor diodes is supplied through R47 and R25 by the output of U5:A in the PLL synthesizer circuit. We know already that there must be a 21.4 MHz difference between the receive and transmit frequencies of the VCO. This swing cannot be accomplished by PLL programming alone. The VCO must be able to stay "in range" with the synthesizer.
Stage E: BASIC VCO ASSEMBLY In this Stage, we will assemble the basic VCO (Voltage Controlled Oscillator) circuit. Understanding the function of this stage is especially important for knowing how the FX transceiver works. E1. Select and install shielded coil L7, stamped 84885-5. It fits in two different ways, and either way will work. Be VERY sure BEFORE soldering that this coil is seated snugly on the PC board. E2. Install C43, .001 uf (marked .001 or 102). E3.
E20. Install R35, upright, 100K ohm (brown-black-yellow). R35 is between positions for D5 and C62. Steps E1-E20 are presented as a group primarily as a help in visualizing the location of the VCO on the PC board. You have built up the VCO itself and the capacitance multiplier voltage filter provided by C40, Q4, etc. After double-checking the accuracy of your work, proceed with installing the VCO related components in Stage F.
F18. Install C35, 100 pf disc capacitor (marked 100 or 101). C35 couples the VCO buffer to the receiver IC. F19. Install C94, a 3.9 pf disc capacitor (marked 3.9). F20. Solder 1/4" lengths of bare wire (trimmed from resistors or capacitors) in the two test point holes marked TP2 and TP3. Study the following optional test procedure before installing a similar test point at TP1.
VCO AND RECEIVER TEST PROCEDURE: 1. Make sure work area is tidied up and that the PC board has been checked for stray scraps of wire, etc. 2. Use your own hookup wire and potentiometer to connect to TP1, +8V and GND as illustrated. 3. Turn power switch OFF and squelch fully counter clockwise. 4. Connect 12V DC, speaker and antenna (2' of wire will do). 5. With power on and volume at a low level, s-l-o-w-l-y turn the temporary tuning potentiometer.
RAMSEY FX-146 VHF FM TRANSCEIVER KIT ASSEMBLY PHASE 2: • Stage G: Understanding and Building the PLL Frequency Synthesizer • Stage H: Building and Programming the Diode Matrixes • Stage M: Microphone Amplifier and PTT Circuit • Stage "TC": Preparing Transmitter Coils, RF Chokes • Stage "TO": Other Transmitter Stage Preparation • Stage TX: Transmitter Buffer, Driver and Final Each set of Assembly Instructions is introduced by an explanation of how that part of the circuit works and what it is fo
Stage G: The PLL Synthesizer: Understanding and Assembly FX 146 • 100
Stage G: The FX- Transceiver PLL Synthesizer A reassuring feature of the FX Transceiver is that if you build it correctly and make just a few adjustments, it will work fine whether you understand how it works or not. For most amateurs and beginners, the functions of the PLL Frequency Synthesizer and VCO will present the greatest challenge to understanding.
Inserted into this circle is the frequency synthesizer (U6 with U3), which compares the output of the VCO with the output of its own 10.24 MHz. Reference Oscillator (see Y2) and also with the frequency programming which you have set up. After making these comparisons, it gives an instruction to the VCO in the form of a precision voltage applied to the varactor diodes, and the cycle repeats itself at lightning speed. Try dividing 10240 KHz by 2048 on your calculator.
soon as both strings are exactly on the same frequency. By tuning the one string to the exact pitch of the other, you have corrected the phasing of the two independent frequency sources. Pilots of multi-engine planes (or boats) make slight RPM adjustments to get all engines in phase. If you have two audio oscillators handy, listen carefully as you adjust both to EXACTLY the same frequency. Another analogy is the process of tuning a BFO equipped receiver to a perfect null or "zero beat.
• • work together for channel programming. The Phase Detector (or "phase corrector") which compares the 5 KHz Reference Frequency with the "intended" 5 KHz output of the divide by N counter and sends correcting pulses to the VCO to keep the output of the N divider right at 5 KHz. A "lock detect signal" circuit.
Unlike simpler PLL IC's, U6's phase detector has TWO outputs at pins 7 and 8. These outputs go through very simple low pass filters (R44-C68, R53C91) to cut back the 5 KHz whine sound of U6 at work. Op amp U5:A sums together the phase detector outputs and the output of U5:A is passed through a network of 2.2 uf electrolytic capacitors (C67,70,90,92) to smooth out the phase detector pulses to clean DC for controlling the VCO.
R48 and C85 form yet another low pass filter to ensure that any 5 KHz "whine" will not get into the VCO. Because the DC charge developed in C85 (.1 uf) would slow down the PLL during major frequency swings, such as just going from transmit to receive, D8 and D10 are set up back-to-back across voltage dropping R48. Whenever there is a major frequency shift (which means a significant VCO control voltage change), one way or the other, one diode or the other is switched on to short out R48 and discharge C85.
finish or review your work. G1a. Insert the 28-pin DIP socket for U6 into its PC board position and slightly bend the 4 outermost pins to hold it in place. G1b. Examine the solder side and verify that ALL 28 pins are extended into their respective holes. G1c. Press the socket squarely onto the board, solder the 4 corner pins, check for proper seating, then solder remaining pins. G2. Install U6, MC145152, checking that all pins are fully seated. G3. Install oscillator crystal Y2, 10.240 MHz.
G18a. Insert and solder U10 as in step G15a. Soldering the remaining pins for U7, U8, U9 and U10 may be done either as a single operation or at any other pace preferred by you to ensure careful work (no missed pins, no solder bridges). As you complete the soldering of each IC, mark its respective assembly step: G15b. 14 pins soldered on U7. G16b. 14 pins soldered on U8. G17b. 14 pins soldered on U9. G18b. 14 pins soldered on U10.
Stage H: Frequency Programming, Understanding and Building your Diode Matrix FX-146 • 109
Stage H: FREQUENCY PROGRAMMING: Understanding and Building the Diode Matrix The labeling of the 16 parallel programming inputs of U6 should have a familiar ring to anyone with at least some understanding of computer principles, which should include all of us by now. Even though our desired "N" number is a five-digit decimal number, it is programmed as a "16 bit" BINARY number. Binary numbers can be as big as you like, but we get there by counting on a base of two, either 1 or 0, yes or no, on or off.
"N" for 146.
before doing any further work on your transceiver. Freq N= 32 K 16 K 8K 4K 2K 1K 512 256 128 64 32 16 8 4 2 1 144.00 28,800 0 1 1 1 0 0 0 0 1 0 0 0 0 0 0 0 148.00 29,600 0 1 1 1 0 0 1 1 1 0 1 0 0 0 0 0 146.
Even though there are 16 matrix positions to program, there are some shortcuts to make your job easier for normal ham band operation. Let's look at the upper and lower band edges for the 2 Meter band: Notice that the values of the highest 6 positions are the same throughout the band. We still must program in those six positions but we only need to calculate for the remaining 10 (512 through 1). Let's look again at the programming of 146.52 MHz Simplex, where N = 29,304.
THE RX/TX OFFSET PROGRAMMING MATRIX Diode placement in this matrix follows the same binary number principles as used for frequency programming. This matrix is connected to the 16 programming inputs of U6 through the four binary adders (U7-U10). Fewer programming positions are provided on the board simply because there is no practical use for extremely large or very tiny frequency offsets. The 1 to 8K range provides plenty of flexibility for non-standard channel spacing.
Easy enough! Whenever you want a transmit offset that is higher than the receiver or repeater output frequency, simply find the the N number for the offset and program it on the offset matrix. Here's one more example. Let's say we want a + 1 MHz offset. 1 MHz = 1000 KHz. 1000 ÷ 5 = 200 = N Converting to binary: (Obviously 200 is less than all values from 8K through 256, meaning that we need no diodes in those positions.
H2: R69, 1K (brown-black-red). H3: R114, 1K (brown-black-red). H4: R65, 1K (brown-black-red). H5: R67, 10K (brown-black-orange). Install the following diodes, be sure to orient the cathode banded end correctly. (Diodes are type 1N914/1N4148): H6: D19 H7: D15 H8a: D13 H8b: D14 H9: D16 H10. Install NPN transistor Q15, type 2N3904. Watch correct orientation of the flat side.
H41. Form one diode matrix "bridge" for the RECV row of holes. Using the heavier gauge bare wire in your kit, shape, insert and solder this wire bridge as illustrated. H42a. Select seven (7) diodes from the master supply of 1N914 or 1N4148 switching diodes provided with this transceiver kit. H42b. Set the PC board across two small boxes, blocks, cups or any objects which provide a couple inches of clearance between the bottom (solder side) and your work surface. H42c.
Frequency Programming and Channel Switch Preparation Before completing the transmit functions of this VHF FM transceiver, we should now verify that the PLL Frequency Synthesizer gives performance as desired and as designed. Regardless of whether you pursued the VCO/ receiving tests proposed as optional in the previous section, it is now time to put your completed receiver section through its paces. In order to do this, one or more receiving frequencies must be programmed on the primary matrix.
Freq (MHz) 32K 16K 8K 4K 2K 1K 512 256 128 64 32 16 8 4 2 1 146.52 162.55 145.01 programming explained in detail in the first pages of this Section. In lieu of constructing diode bridges and wiring the channel selector switch, you may elect to build your own switching system, using DIP, slide or toggle switches. Do such projects only after your transceiver is finished and working. Channel Switch S2 may be installed at whatever point in the procedure that is most convenient for you.
C60 until instructed to do so. Adjustment Procedure: 1. Check PC board carefully for missed connections, wire trimmings or untrimmed wires bent down, etc. 2. Connect speaker and DC supply voltage. 3. Obtain or make a non-metallic alignment blade capable of adjusting L7 and C81. 4. Set frequency to the channel you selected for 146.52 MHz Simplex. 5. Turn on the unit and verify normal operation of squelch and volume controls. 6. Connect an accurate voltmeter to TP1 and adjust L7 for 1.27 volts (1.25 to 1.
If the receiver section is not working, going ahead with Stage M or Stage TX is very unlikely to fix the problem. Nor is there much point calling the Ramsey factory for a quick fix or "what do I check?" because all a technician can really tell you is to double-check your work. It is virtually imposible to trouble-shoot your unit over the phone.
Stage M: Microphone Amplifier and PTT Circuit If you have studied all preceding circuit explanations, you have a good idea of what the Microphone and PTT circuitry is supposed to accomplish. Understanding our design clearly and assembling it correctly will save many headaches and will ensure reliable FX transceiver operation. U4 is a "quad op amp" which means 4 operational amplifiers in one DIP package.
assures that the otherwise-silent PTT circuitry is indeed functioning and obviously has nothing to do with the RF output of the transmitter. The PTT circuit may also be activated at pin 3 of the Packet I/O jack. A direct short to ground is not necessary. The author noted very positive PTT action with resistance as high as 100K from pin 3 to ground.
M18. Install Q11, NPN transistor type 2N3904. Be sure to orient flat side as shown. M19. Identify and install R46, the yellow color modulation control trimmer potentiometer. It differs from trimmer capacitors by having three terminals. Simply place it in position and solder all three points. NOTE: The remaining three transistors used in this section are PNP types, 2N3906 or similar, marked 228256. It is essential to use the correct transistor type for Q12, Q13, Q14. M20.
during transmit. M35: R107, near Y1, 10K (brown-black-orange). M36: D22, near VR1, type 1N914 or 1N4148. Orient the banded end correctly. (+8T through R107 and D22 turns on Q6 to mute the audio amp IC during transmit). M37: C62, near R113, .001 uf. M38: Diode D5, near R35, type 1N914 or 1N4148. M39: R31, near D5, 47K (yellow-violet-orange). M40: R33, also 47K (yellow-violet-orange). M41: R70, near diode matrix, 1K (brown-black-red).
background noise is audible.
6. Press the microphone button: the TX LED should light, and the receiver should be silenced. 2.5 TURN 1.5 TURN 7. Touch a wire from ground to pin 3 of the Packet I/O jack. Do the same with any resistor that is 47K or lower. Either way, you should get the same results as in Step 6. 8. Disconnect the DC Power. OPTIONAL: Interested builders might wish to verify microphone amplifier operation at PC board point "PL" before proceeding, but such a test is not essential at this point.
Stage TX: Transmitter, Buffer and Final Amplifier FX 146 • 128
Stage TX: Transmitter Buffer, Driver and Final The transmitter section, Q10, Q9 and Q8, is conventional VHF RF circuitry that has proven quite reliable in Ramsey transceivers. Just a few circuit notes are in order. Transistor Q10, the transmit Buffer, amplifies the VCO output from C56 to about 10 milliwatts, quite sufficient for checking modulation and PLL alignment in transmit mode as soon as this stage is built. Operating bias is supplied by the PLL lock detect voltage from U5B through R110.
IMPORTANT: DO NOT install any parts near Q8 until after Q8 has been installed in accord with the explicit directions in Step TX2. If you fail to observe this caution, it will be virtually impossible to perform the installation of Q8 correctly. DO NOT INSTALL L9, R32 or L10 UNTIL AFTER ALIGNMENT HAS BEEN COMPLETED. C75 is a SMT (surface-mount-technology) "chip" capacitor and is the only part installed on the SOLDER SIDE (bottom) of the board. TX1. Install Q9, RF NPN type 2N3866.
B. Unpack and study the design of the chip, noting both ends are metallic. C. Lightly pre-tin both PC board points. D. Holding C75 in place across the two tinned points with tweezers, gently touch one junction with the soldering tip. The connection should solder easily. E. Solder the other end and touch up the first one if necessary. Identify and install the following components: TX4: C56, 10 pf. TX5: R29, 100 ohms (brown-black-brown). TX6. L11, miniature .33 uh.
However, DO NOT INSTALL L9, R32 or L10 UNTIL AFTER ALIGNMENT HAS BEEN COMPLETED. Whether you test now or later depends on how anxious you are to see (and hear) the results of all your hard work. If you are still awaiting your ham license, you can test the FM modulation of buffer stage Q10 and also enjoy your receiver fully. Be aware, however, that the buffer stage, even with no antenna connected to it, has a transmitting range of about 100 feet, even through walls and obstacles.
8. While speaking in the microphone, adjust modulation level (R46) for the best sounding speech. "Best" is not necessarily the maximum: see the following note. NOTE: R46 adjusts the FM deviation of the transmitted frequency. Deviation is carrier frequency swing in step with voice modulation. If you "over-deviate," your signal will not be stronger. Instead, the speech will become distorted and "splash" over to adjacent channels.
TX26: C58, the last .1 uf capacitor. TX27: C59, .001 uf. TX28: L13, 1.5 turn hand-wound coil. Review "TC" and TX16. TX29 C73, 18 pf. TX30: C55, .01 uf. TX31: C74, 35 pf trimmer. TX32: C84, 35 pf trimmer. TX33: C64, .001 uf. TX34: L8, 2.2 uH molded inductor (2 red, 1 gold and 1 black stripe). At this point, every single main PC board component has been installed except for L10, R32 and L9, which apply power to the RF output transistors (driver Q9, final Q8).
the lead preventing a good solder connection, you may wish to slightly scrape away this coating on some parts. TX35. Install R119a, 1K (brown-black-red). TX36. Install D26, 1N914/1N4148 diode, observe correct placement of the cathode band. TX37. Install C71, 39 pf. TX38. Install C19, 56 pf. TX39. Install C72, 39 pf. TX40. Install L12, the 2 1/2 turn coil prepared in stage TC. Insertion will require you to spread the windings slightly to fit the holes.
main PC board.
This completes the assembly of the low pass filter PC board. Inspect the board to be sure all leads on the bare side of the board are trimmed neatly and that the coils do not short against the PC board ground plane. TX45. Exactly when to install the SO-239 antenna RF connector is left to your discretion. If you are using your own case, you must now "wing it" on your own, observing the way we are mounting the connector to our case.
good 50 ohm load. Keep these key-down tests as brief as possible. TX52. If you are observing at least 4 watts of RF output, transmitter tuneup is completed. Spread coils L13 and L16 on the main board and L12 and L22 on the low pass board for maximum RF output. These coils are purposefully wound with a little too much inductance, so that they can be easily "peaked" by some spreading. This is probably one of the most important steps to get the most RF out of your rig. TX53.
FX-146 TECHNICIAN’S NOTES Throughout production of the “FX” series transceivers, the technicians here at Ramsey have been speaking with customers, making repairs, experimenting, and compiling notes on the FX-146. These notes, and the circuit overview and theory of operation sections of your FX-146 manual, provide extensive information on the inner workings of the FX-146. Should a nasty gremlin jump into your trusty new FX-146, this information will help lead your foray into troubleshooting.
help after all. VCO & PLL Faults: (manual pages ref. 21-24, assm.35-36, 43-48, 52-57) 1. PLL not locking. (L7 will not set correct voltage @ TP1) a. Check for proper programming inputs to U6 (pins 10-25). If VOLTAGES ON U6 @ 146.
back to the manual, isn’t our “n” number for 10 Khz right about 2? c. Some coincidence! Now we can guess that our fault is between the # 2 position trace and the input to U6.) d. Some channels are off frequency by different amounts. (Refer to preliminary check # 5) *Common faults: • Improper diode programming. • Solder shorts between traces. (There’s a lot of traces between U6 and the diode matrix!) Transmit Section Faults: (manual pages ref. 26, assm. 72) 1. No power output. a.
output by spreading the coils.) *Common faults: • Low supply voltage. • Improper tuning. • Improper output power measurement. Receive Section Faults: (manual pages ref. 20-21, assm 22-24, assm 30) 1. Poor or no receive. Lots of audio hash. a. Check for proper VCO frequency. b. Ensure pin diode D6 is forward biased (anode ~ 2.7VDC, cathode ~ 2.0 VDC) and pin diodes D2 and D7 are reverse biased (D2 anode ~ 0VDC, D7 anode ~ 0VDC, cathode ~ 2.0VDC). c. Check preamp transistors Q2 and Q3 for proper operation.
FX-146 • 143
FX 146 • 144
FX-146 • 145
