Ramsey Electronics AM25, Assembly And Instruction Manual

Page 1: ...h for high school college or neighborhood radio station in use the world over Easily programmed via DIP switch to any clear channel on the AM broadcast band from 540 to 1710 KHz Operates on the same p...

Page 2: ...IO 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 sc...

Page 3: ...ic Diagram 7 Parts Layout Diagram 8 Parts List 9 Assembly Instructions 10 Frequency chart 18 Alignment Procedures 19 Troubleshooting 20 FCC Information 20 Antenna Experimenting 22 Ramsey Kit Warranty...

Page 4: ...radio stations Re broadcasting received audio for shortwave or HAM radio use Listening aid for auditoriums churches or other events Short range experimentation We think that you will be very pleased w...

Page 5: ...ng auto transformer L4 from Q8 and Q9 thus producing an AM output waveform This signal is then low pass filtered using C1 C7 and inductors L1 3 Notice that the audio information is applied at the powe...

Page 6: ...from the VCO Voltage Controlled Oscillator and divides it by a number that we ll call N N is the frequency data that was sent by U2 and N is always equal to the desired frequency in megahertz times 10...

Page 7: ...AM25 7...

Page 8: ...AM25 8 PARTS LAYOUT DIAGRAM...

Page 9: ...0 pF disc capacitor marked 0022 or 222 or 2200K C2 3 6 7 2 3900 pF disc capacitor marked 0039 or 392 or 3900K C4 5 2 4700 pF disc capacitor marked 0047 or 472 or 4700K C4 5 2 5600 pF disc capacitor ma...

Page 10: ...atsinks 80 enameled magnet wire 2 4 40 x 1 4 screw 2 4 40 kepnut ASSEMBLY INSTRUCTIONS There are numerous solder connections on the AM25 printed circuit board Therefore PLEASE take us seriously when w...

Page 11: ...tched ends of IC s and so forth 6 Solder all connections unless directed otherwise Use enough heat and solder flow for clean shiny completed connections 7 Trim or nip all excess wires extending beyond...

Page 12: ...intain frequency exactly as programmed 12 Install C13 01 uf disc capacitor marked 01 or 103 of 10 nf 13 Install C14 another 01 uf disc capacitor 14 Install jumper JMP2 Simply use a small scrap of comp...

Page 13: ...llow violet brown 28 Install Q10 2N3904 transistor Be sure to orient it correctly See the parts diagram for correct orientation 29 Install Q2 another 2N3904 transistor watch that flat side 30 Install...

Page 14: ...mishaps Later stages of the transmitter require extra care so better to catch errors now rather than later 49 Install C19 001 F disc capacitor marked 001 or 102 50 Install R20 1 K ohm brown black red...

Page 15: ...tion burn off and a nice coating of solder attach to the copper wire under the enamel insulation Gosh it takes longer to explain than to do it 66 Position the wire ends so that the three wires are in...

Page 16: ...k brown 83 Install JMP3 using a scrap component lead wire 84 Install Q8 2N3904 transistor observe placement of the flat side 85 Install C17 01 F disc capacitor marked 01 or 103 or 10nF 86 Install C22...

Page 17: ...ncy you wish to set your transmitter to It really is not sufficient to just check the AM band for an empty frequency using the AM radio closest at hand It is your responsibility to research what AM st...

Page 18: ...entire circuit board Energizing the circuit board with solder bridges or misplaced components can damage your kit ANTENNA CONSIDERATIONS For many applications a 5 6 foot wire antenna connected to the...

Page 19: ...6 close switched 128 16 and 2 A calculator comes in handy when you successively subtract the binary numbers 128 64 4 2 1 It really is quite easy and fun to find the right switches to close ALIGNMENT P...

Page 20: ...o double check the assembly steps going backwards from the last step to the the first Bright lighting and a magnifying aid can be helpful in identifying soldering problems Use a methodical logical tro...

Page 21: ...listeners have all the rights Your non licensed use of any device such as the AM25 has absolutely no rights at all over the rights of a licensed broadcast operator If your operation of the AM25 interf...

Page 22: ...Here s a neat antenna idea the 1 1 2 PVC loading coil will fit nicely into 2 diameter PVC pipe Get a 10 foot length run the long antenna wire up through the pipe and over the edge a bit slip a PVC pi...

Page 23: ...be 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 b...

Page 24: ...for RAMSEY MODEL NO AM25 SYNTHESIZED AM TRANSMITTER KIT REQUIRED TOOLS Soldering Iron WLC100 Thin Rosin Core Solder RTS12 Needle Nose Pliers MPP4 or RTS05 Small Diagonal Cutters RTS04 ADDITIONAL SUGGE...