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  FM10C 1 

FM STEREO 

TRANSMITTER 

Ramsey Electronics Model No.        FM10C 

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Great for transmitting your tape deck or CD player throughout the 
house, yard or even your car. 

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Powerful enough for college or neighborhood radio stations - in 
use all over the world. 

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Fantastic audio quality sounds better than most stations on the 
dial.  And we’ll tell you why! 

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Easily connects to the line-level outputs on any tape deck, stereo 
system or CD player. 

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Some users hook up one channel to the scanner and the other to 
their two way radio.  Now you can hear what’s going on around 
town up to several blocks away from your house with a simple 
stereo receiver... and adjust the volume of each individually with 
your balance control! 

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Add a mike-mixer and tape/CD deck for a “PRO” sounding station. 

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Operates on 5 to 20 volts, using a crystal controlled subcarrier. 

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Tunable anywhere in the 88-108 MHz FM band. 

Own and operate your own FM Stereo broadcast station.  
Definitely not a toy, the FM-10C has an exceptional transmission 
range... and the audio quality puts your favorite radio station to 
shame.  See why this is one of our most popular kits! 

Summary of Contents for FM10C

Page 1: ...hannel to the scanner and the other to their two way radio Now you can hear what s going on around town up to several blocks away from your house with a simple stereo receiver and adjust the volume of...

Page 2: ...MSEY AMATEUR RADIO KITS DDF1 Doppler Direction Finder HR Series HF All Mode Receivers QRP Series HF CW Transmitters CPO3 Code Practice Oscillator QRP Power Amplifiers RAMSEY MINI KITS Many other kits...

Page 3: ...18 Adjusting your FM10C 20 Using FM10C Within the Home 21 Power Supply Considerations 21 LED Power On Indicator 21 Experimental Broadcasting Projects 22 Antenna Ideas 23 Troubleshooting Guide 24 Appen...

Page 4: ...ality frequency stability and stereo channel separation of this build it yourself FM stereo transmitter If you follow our assembly directions carefully and use your FM10C in accordance with applicable...

Page 5: ...9kHz pilot signal and RF Carrier 88 108 MHz The control of U1 is determined by its surrounding circuitry as described in the following paragraphs Audio We will look only at the left channel circuitry...

Page 6: ...to the transistor Q1 R11 sets the bias or operating point of Q1 R12 is the collector load resistor that develops the output signal and brings in DC power RF Output C23 couples the RF output signal to...

Page 7: ...FM10C 7 FM10C PARTS LAYOUT DIAGRAM...

Page 8: ...electrolytic capacitor C4 INDUCTORS 3 2 2 uH red red gold L1 2 3 1 13 turn air core inductor L5 1 Adjustable shielded inductor coil L4 small square silver can RESISTORS 1 200 ohm 1 2 watt red black b...

Page 9: ...eet 1 Button for DPDT switch REQUIRED NOT SUPPLIED 9 volt alkaline or heavy duty battery Shielded stereo audio cables Line level output audio source such as a tape deck or CD player OPTIONAL LED power...

Page 10: ...at the traces to which you are soldering heating both wires and pads simultaneously Apply the solder to the iron and the pad when the pad is hot enough to melt the solder The finished joint should loo...

Page 11: ...e us a call at the factory We will be happy to help you with any problems you may run into This is a mixed signal project meaning there is digital audio and RF circuitry all in one unit As with all RF...

Page 12: ...ight chan nel of the modulator IC Seat it flat before soldering 10 Install R4 another 1K ohm trimmer potentiometer marked 102 This pot is used to adjust the audio level to the left channel of the modu...

Page 13: ...has no polarity require ments so its leads can be placed in either of the two holes 20 Install crystal strap using a scrap component lead looped around the crystal and placed through the other two cry...

Page 14: ...ator 38 Install C17 a 001uF ceramic capacitor marked 102 39 Install C19 a 10pF ceramic capacitor marked 10 40 Install shielded slug tuned coil L4 The larger tabs secure the shield can to the ground fo...

Page 15: ...ll 53 Install R13 a 1K ohm resistor brown black red 54 Install L5 a 13 turn air core coil Just as with the other inductors polarity is not an issue 55 Install ANT1 a telescoping antenna Insert the scr...

Page 16: ...p Also look for potential solder bridges the parts layout diagram can help with that You may want to hurry and get the kit powered up but any thing you find now will save you a lot more trouble later...

Page 17: ...the groove side is on your left 2 Place the front panel in the groove of the case bottom in the side that is facing you 3 Place the circuit board in the case bottom so that the DPST switch comes thro...

Page 18: ...FM10A 18 FM10C REV2 1 SCHEMATIC DIAGRAM...

Page 19: ...FM10C 19...

Page 20: ...cess for the right channel and R3 Hooking up an audio source to your FM10C is really quite simple However there are some general rules A terribly distorted sound is a sign of too much audio level Simp...

Page 21: ...ility to suppress unwanted AC line hum Various plug in adapters and power supplies in the 6 to 12 volt range may be tried but make sure the unit has DC output positive tip and is not merely a transfor...

Page 22: ...2 It would be an excellent class family or Scout project 3 Commercially made stereo mixing consoles while much less expensive today than a decade ago will cost much more than did your FM10C kit 4 The...

Page 23: ...nnected to the center conductor of the coax should be the upper higher end If young children will be around the set up a flexible wire antenna is preferable rather than rigid tubing A ground plane ant...

Page 24: ...lation is beyond the original purpose of this kit and the safety standards intended for all Ramsey kits and because we have not tested the FM 10A in such an installation we cannot provide further deta...

Page 25: ...of Documents at 202 512 3238 or fax at 202 512 2250 To order the correct document ask for CFR Title 17 Parts 1 to 19 The cost is 24 00 Master Card and Visa accepted In the United States this is how t...

Page 26: ...id any and all interference to licensed FM broadcast transmission and reception This instruction manual gives you practical advice on how to do a good job of finding a clear frequency if one is availa...

Page 27: ...eneral conditions of operation b Operation is subject to the conditions that no harmful interference is caused and that interference must be accepted that may be caused by the operation of an authoriz...

Page 28: ...but the field strength voltage is only halved Using this theory we can construct a simple chart to show the maximum permitted performance of a non licensed FM band transmitter The theoretical figures...

Page 29: ...easy the numbers would get too cumbersome if we discussed your possible signal coverage in terms of square feet or square meters 2 It s very easy to see that your signal can easily and legally serve...

Page 30: ...ower transmitter such as the FM10C The main point is that you may not cause any interference whatso ever to licensed broadcast services and that you must be willing to put up with any interference tha...

Page 31: ...C is toughest about clandestine transmission which cost time and money to track down 10 Do not assume that the mere fact that you purchased this kit gives you any specific right to use it for any purp...

Page 32: ...pose of this kit manual will show you many legal uses of radio transmitting devices which do not require licensing either amateur or commercial To provide more personal and club radio learning opportu...

Page 33: ...vpp Line Level Pre emphasis 75uS or 50uS component selected Stereo Separation 45 dB typical Power Supply Requirements Jack 2 1mm center External Supply Voltage 5 to 20 VDC External Supply Current 60mA...

Page 34: ...____________ ______________________________________________________________ ______________________________________________________________ _____________________________________________________________...

Page 35: ...actory for a full refund less shipping The return package should be packed securely Insurance and tracking is highly recommended A reminder this applies to unassembled kits They must be in the same ne...

Page 36: ...TOOLS Soldering Iron Thin Rosin Core Solder Needle Nose Pliers Small Diagonal Cutters ADDITIONAL SUGGESTED ITEMS Helping Hands Holder Desoldering Braid TOTAL SOLDER POINTS 151 ESTIMATED ASSEMBLY TIME...

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