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Ramsey Electronics DDF1, Manual

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DDF1 

•

 3  

DOPPLER RADIO 

DIRECTION FINDER 

Ramsey Publication No. MDDF1 

Price $5.00 

TABLE OF CONTENTS 

 

Introduction to the DDF1 ...............  4 
DDF1 Circuit Description ..............  4 
Parts List ...................................... 11 
DDF1 Assembly Steps ................. 14 
Component Layout ....................... 17 
Schematic Diagram ...................... 18 
Initial Testing ................................ 22 
Ramsey Warranty ........................ 23 

 

INSTRUCTION MANUAL FOR 

Summary of Contents for DDF1

Page 1: ...ign thanks to WA2EBY Featured in May June 1999 QST Articles Solid state antenna switching for rock solid performance Convenient LED 22 5 degree bearing indicator Audio Level indicator for trouble free...

Page 2: ...ITS DDF1 Doppler Direction Finder 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 ava...

Page 3: ...Publication No MDDF1 Price 5 00 TABLE OF CONTENTS Introduction to the DDF1 4 DDF1 Circuit Description 4 Parts List 11 DDF1 Assembly Steps 14 Component Layout 17 Schematic Diagram 18 Initial Testing 2...

Page 4: ...ion The signal received from an antenna moving away from the source of transmission appears to be lower in frequency than that of the actual trans mission Imagine a receiving antenna moving in a circu...

Page 5: ...the received signal in megahertz dF The Doppler shift in Hertz R Radius of antenna rotation in inches fc Carrier frequency of the received signal in megahertz As an example let s calculate how fast t...

Page 6: ...Doppler RDF circuit see the block dia gram of Figure 2 An 8 kHz clock oscillator drives a binary counter The out put of the counter performs three synchronized functions spin the antenna drive the LE...

Page 7: ...nfigured as an astable multivibrator C26 R27 and R28 R29 determine the multivibrator s oscillation frequency R27 and R28 are series connected to allow fine tuning the oscillation frequency to 8 kHz It...

Page 8: ...ED display sequences through four direction indicating LED s then switches to the next antenna Each direction indicating LED represents a heading change of 22 5 degrees The third synchronized function...

Page 9: ...verage rapid Doppler tone changes caused by multipath reflected signals noise or high audio peaks associated with speech A digitized representation of the Doppler tone is provided at the digi tal filt...

Page 10: ...11 similar to the low level lock out function Phase Correction If the audio output of the Doppler RDF FM receiver is incorrectly phased S3 phase invert can fix that If phasing is incorrect LED directi...

Page 11: ...31 34 35 38 43 45 1 56K ohm green blue orange R12 2 68K ohm blue gray orange R29 33 1 100K ohm brown black yellow R18 3 220K ohm red red yellow R15 21 23 1 PC mount 10K trimmer potentiometer 103 R50...

Page 12: ...8 1 74HC161 IC 16 pin DIP IC U7 1 74HC4051 IC 16 pin DIP IC U5 1 74HC4515 IC 24 pin DIP IC U11 3 324 Op Amp IC 14 pin DIP marked 324 U1 2 3 2 555 Timer IC 8 pin DIP IC marked 555 U4 6 MISCELLANEOUS CO...

Page 13: ...holes Second whenever possi ble we install in an order that fits our Learn As You Build Kit building phi losophy This entails describing the circuit that you are building instead of just blindly inst...

Page 14: ...or con nection Be sure to push the part as close to the circuit board as it will go as the alignment of this part is important in getting the case holes to line up with the part Solder all three leads...

Page 15: ...ensure proper polarity See the parts diagram for proper placement The capacitor should fit snugly down to the PC board Now it s time to build the power supply regulation portion of the circuit We nee...

Page 16: ...g for fox transmitters in baby strollers at the mall Let s get back to it Next we ll work on the digital filter section of the circuit Be sure to mount the components as close to the printed circuit b...

Page 17: ...DDF1 17 DDF 1 MAIN BOARD PARTS LAYOUT DIAGRAM...

Page 18: ...DDF1 18...

Page 19: ...DDF1 19...

Page 20: ...ed 104 That concludes most of the digital circuitry included in your kit take a mo ment to recheck your work We ll get started now on the audio processing section of the direction finder kit 39 Locate...

Page 21: ...e parts layout diagram 53 Install R16 10K ohm brown black orange There is another plated through hole inside the silkscreen for R16 that is not the installation hole Be sure to install the resistor le...

Page 22: ...ed red yellow 72 Install R22 10K ohm brown black orange 73 Install electrolytic capacitor C8 1 uF Be sure to orient the part cor rectly 74 Install R18 100K ohm brown black yellow 75 Install the last 3...

Page 23: ...ed flush to the circuit board and solder into place The switches are DPDT type so up down orientation is not critical Check the placement of each switch by test fitting the circuit board into the uppe...

Page 24: ...lder into place The main board assembly is complete You are that much closer to a func tioning Doppler DF system Take a break you have accomplished the big gest chunk of the kit When we start up again...

Page 25: ...ntenna whip to each ANTMTG board 1 Install the 1N4148 diode on the ANTMTG circuit board in the same manner in which you installed them on the switcher keeping those leads as short as possible 2 Instal...

Page 26: ...the an tennas themselves To create the necessary holes for both the mounting screw as well as the cable inputs take your soldering iron and melt a half moon shape in the side of the lid to allow clear...

Page 27: ...ap can be permanently installed using a hot melt glue gun or other sealer of your choice INITIAL TESTING Basic Testing It is wise to review your workmanship looking for circuit shorts or opens prior t...

Page 28: ...respectively Verify the presence of a square wave signal on pins 2 4 6 and 8 of buffer U12 Signal Level Indicators The following test uses an audio signal generator to simulate the presence of the Dop...

Page 29: ...on takes place Calibration Control Verify the function of the calibrate control by adjusting the audio generator equal to the antenna rotation frequency At this point only a single LED will illuminate...

Page 30: ...nna switcher to an FM receiver or transceiver tuned to a strong NOAA weather broadcast signal Caution Make sure you disable transmit mode if you are using a transceiver Apply power to the RDF unit and...

Page 31: ...ith respect to your location and the position of the car Have the driver slowly circle while you observe the display You should see the di rection indicating LED move in the opposite direction as the...

Page 32: ...UHF frequency FINAL CASE UP When all your tests are complete you will want to case up your main PC board First attach the overlay to the plastic case front The best only way to do this is to spray th...

Page 33: ...ts and or bad solder connections Working backwards through the assembly steps will often lead you to the problem Please understand that it is nearly impossible to troubleshoot by phone any specific qu...

Page 34: ...DDF1 34 DDF 1 ANTENNA SCHEMATIC DIAGRAM...

Page 35: ...e assured that the 1K ohm resistors are actually the missing 10 K parts Hum m m I guess the red band really does look orange Ramsey Electronics project kits are packed with pride in the USA If you bel...

Page 36: ...itial Testing 22 Ramsey Warranty 23 Price 5 00 Ramsey Publication No MDDF1 Instruction manual for RAMSEY MODEL NO DDF1 DOPPLER RADIO DIRECTION FINDER REQUIRED TOOLS Soldering Iron WLC100 Thin Rosin Co...

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