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Ramsey Electronics Model No.       FM-100 

Now here’s the ultimate radio transmitter for all of you home 
brew DJs out there! This all-in-one stereo transmitter has all 
the features you will ever need for transmitting for a school 
radio station, around your yard, or even around the block. 
With an optional high power module for out of the US 
transmitting, this is definitely a professional unit! 

2 Line inputs and one mic input-plus a built in mixer! 

PLL Crystal controlled for rock solid frequency 

Left and right channel peak hold indicators and large LED 

frequency display 

Built in power supply, just plug it in! 

25mW output standard, optional 1W module for foreign 

country operation 

Auto AGC microphone muting function for cool talk overs 

Rugged steel enclosure for years of use 

Summary of Contents for FM-100

Page 1: ...an optional high power module for out of the US transmitting this is definitely a professional unit 2 Line inputs and one mic input plus a built in mixer PLL Crystal controlled for rock solid frequenc...

Page 2: ...AMATEUR RADIO KITS FX 146 VHF Transceiver HR Series HF All Mode Receivers QRP Series HF CW Transmitters CW700 Micro Memory CW Keyer CPO3 Code Practice Oscillator QRP Power Amplifiers RAMSEY MINI KITS...

Page 3: ...e 10 00 TABLE OF CONTENTS Introduction 4 How does it work 5 Parts List 13 Assembly Index 16 Section Layout 17 Display Layout 18 Main Board Layout 21 22 Schematic Centerfold 34 35 Troubleshooting 51 Us...

Page 4: ...comment here is the result of months of design and years of stereo transmitter experience The FM 100 has all of the features needed to run a professional sounding radio station It includes extensive a...

Page 5: ...VDC and then smoothed out with C86 and C52 both 3300uF capacitors These big capacitors were required to reduce ripple in the power supply to a minimum and therefore reducing 120Hz noise in the audio o...

Page 6: ...of U6 we simply send U2 divide by N data to produce the desired frequency from the BA1404 s VHF oscillator The oscillator s frequency is divided by this value N producing an output in the 100KHz regio...

Page 7: ...he power supply The low level RF output of U6 is then fed to Q2 and surrounding parts to boost it to a more reasonable level for filtering Since the RF output of the BA1404 is not the cleanest much fi...

Page 8: ...R62 or R84 R62 and R84 control each line level s transmission volume These levels are then summed in U8 A so now both signals are present on pin 1 of U8 This signal is then sent through R63 which whe...

Page 9: ...r in time the peak hold function is The voltage on the peak hold is then observed by using a LM3915 bargraph display driver U12 and a ten segment bargraph This part is pretty self explanatory it s rea...

Page 10: ...it in setup mode 4 Yes increase the frequency value in RAM by 200KHz 5 Send the appropriate divide by N to the PLL U2 along with the rest of the required data 6 Decode the display digits then send the...

Page 11: ...ng heating both wires and pads simultaneously Apply the solder on the iron and the pad when the pad is hot enough to melt the solder The finished joint should look like a drop of water on paper somewh...

Page 12: ...these steps 1 Pick the correct part value to start with 2 Insert it into the correct PC board location making sure the part is mounted flush to the PC board unless otherwise noted 3 Orient it correct...

Page 13: ...stripe on one end D6 7 21 22 23 24 5 1N4148 small signal switching diodes small orange glass body with black stripe D1 4 5 8 9 1 BB609 Varactor diode black diode with green band D10 3 BS170 N Channel...

Page 14: ...2 C7 8 14 24 25 26 28 36 41 45 62 75 87 88 90 2 0047uF ceramic capacitors marked 0047 or 472 C61 74 13 01uF ceramic capacitors marked 01 10n or 103 C3 10 17 20 21 48 49 53 54 79 80 81 83 6 1uF ceramic...

Page 15: ...e panel 1 Top case half 14 4 40x1 4 board mounting screws 6 6 32x1 4 self tapping black case screws 2 4 40x5 8 self tapping machine screws 1 Fuse holder with hardware 1 1 Amp fuse 1 110 Volt line cord...

Page 16: ...crowded sections of the board Following is a list of all the sections in the manual that we will be going into A Display Board 18 B Part Preparation 23 C Microphone Amp 24 D Mixers 25 E Switched Capa...

Page 17: ...FM 100 Page 17 SECTION LAYOUT ON MAIN BOARD...

Page 18: ...FM 100 Page 18 DISPLAY BOARD LAYOUT Parts Layout Parts Values Note Gray components are on the reverse side of the board...

Page 19: ...facing in the same direction as shown in the parts layout diagram Solder all 18 pins checking for solder bridges when done 5A Install U5 the other LM3915 Log scale bargraph driver Again make sure all...

Page 20: ...side of the board The parts on the back side of the board are marked in gray instead of black 13A Install J3 a five pin jumper block short leads go into the board Again make sure you are putting them...

Page 21: ...FM 100 Page 21 MAIN BOARD PART VALUES...

Page 22: ...FM 100 Page 22 MAIN BOARD PART LAYOUT...

Page 23: ...here When done winding use a hot soldering iron and fresh solder to tin the ends of the wire This takes a little heat and patience but the enamel will burn off without any need for scraping Set this...

Page 24: ...s shown in the layout 9C Install R55 a 10K ohm resistor brown black orange 10C Install R41 another 10K ohm resistor brown black orange 11C Install R25 a 220K ohm resistor red red yellow 12C Install R3...

Page 25: ...esistor red red orange 11D Install R47 a 1K ohm resistor brown black red 12D Install R57 a 10K ohm resistor brown black orange 13D Install R63 a 10K ohm resistor brown black orange 14D Install R71 a 1...

Page 26: ...r 28D Install C76 even another 10uF electrolytic capacitor 29D Install C77 a 10uF electrolytic capacitor 30D Install C80 a 01uF ceramic capacitor marked 01 10n or 103 31D Install Q6 the last of the BS...

Page 27: ...l R69 another 4 7K ohm resistor yellow violet red This resistor and R61 form a voltage divider for the MAX291 ICs opamps since they need to run from the 5 volt supply The divider creates 2 5 volts whi...

Page 28: ...2E Install C70 a 100pF ceramic capacitor marked 100 or 101 23E Install C66 a 1uF ceramic capacitor marked 1 or 104 24E Install C65 a 10uF electrolytic capacitor Check its installation Check you work u...

Page 29: ...right 12F Install R51 a 100K ohm resistor brown black yellow Stands upright 13F Install R54 a 47K ohm resistor yellow violet orange 14F Install D9 a 1N4148 type diode orange glass body with black stri...

Page 30: ...marked 102 or 001 25F Install U11 a LF347 low noise opamp Make sure and orient it in the same direction as shown in the parts layout Also check for all 14 pins to be through the board before solderin...

Page 31: ...nstall the part in a lay down fashion so that we can strap the crystal to the board with a jumper so that it is secured in place Lay it down in the orientation shown then use a scrap piece of lead to...

Page 32: ...7G Install R8 a 10K ohm resistor brown black orange 18G Flip the board over and find the hole where the whip antenna mounts Insert the antenna screw 4 40X1 4 into the hole so that the threads are poin...

Page 33: ...ked 5 or 5K 41G Install C27 a 10pF ceramic capacitor marked 10 or 10K 42G Install C32 a 10pF ceramic capacitor marked 10 or 10K 43G Install C87 a 001uF ceramic capacitor marked 001 or 102 44G Install...

Page 34: ...iented as shown in the parts layout diagram Notice because these are not a standard transistor the pin out is not C B E like with 2N3904 transistors instead it is B E C Base Emitter Collector 60G Inst...

Page 35: ...Install R19 a 1K ohm resistor brown black red 9H Install Q3 a 2N3904 switching transistor Make sure when installing that the flat side is facing in the same direction as shown in the layout 10H Insta...

Page 36: ...on to the EEPROM circuit I EEPROM EEPROM is where the operating frequency last used is stored so that the next time you power up the unit it goes right back to that frequency It sure beats having to r...

Page 37: ...potentiometers Install this part so that its shaft is perfectly parallel to the PC board before soldering It is easy enough to reheat the pads and adjust the pots so they align properly to the holes...

Page 38: ...e most picky eye that you possess We have installed many parts up to this point in time and chances are you have made a mistake somewhere Even the best of kit assemblers are known to make mistakes whe...

Page 39: ...talled correctly 3K Install D23 a 1N4002 type rectifier diode orientation 4K Install D24 another 1N4002 type rectifier diode line end installed correctly The four diodes we installed form a bridge rec...

Page 40: ...rity before installing 16K Install VR3 the 7805 5 volt power regulator We want to mount this flat to the board as shown in the diagram The tab side of the part should be facing the board Install HS1 b...

Page 41: ...tly to the board The copper of the PC board works well as a heat sink for this part 22K Install C4 a 1uF ceramic capacitor marked 1 or 104 23K Install C5 a 100uF electrolytic capacitor Watch polarity...

Page 42: ...ed 103 01 or 10n 7L Install C83 a 01uF ceramic capacitor marked 103 01 or 10n 8L Using a scrap piece of component wire install a wire in the hole marked TP2 Make sure this wire is long enough to conne...

Page 43: ...is a small catch tab on one side of the pin Insert the pin into the Molex jack so the tab faces the side with the slotted holes You should hear a small click when installed properly 6M Install the cen...

Page 44: ...ing the included hardware 15M Solder the wire from point A on the PC board to the center pin of the F connector That should take care of that We are almost ready to plug it in the wall and give her a...

Page 45: ...board 1O Mount the main board to the bottom of the case making sure the holes line up with the standoffs in the bottom Note that you will be install ing 5 board screws the screw under the power switch...

Page 46: ...imal point should blink indicating setup mode 6P Press FREQ UP until the display shows 107 9 MHz if it does not already 7P Connect your voltmeter between the exposed part of R11 and ground Adjust L1 w...

Page 47: ...o the microphone and verify that the music mutes while you talk 21P Press the AUTO AGC button again to turn it off Talk into the microphone and verify your voice is now mixed with un muted music 22P T...

Page 48: ...the holes for the RCA jacks on the back panel This prevents physical damage to the RCA jacks 4Q Use the four sticky pad feet on the bottom of the case in each corner 5Q Install all five switch button...

Page 49: ...t completely other one sounds OK SOLUTION More than likely a short somewhere in any one of the audio sec tions These are usually a bugger to find without a signal tracer or an oscillo scope Inject a s...

Page 50: ...re quency using the FM portable radio closest at hand It is your responsibility to carefully research what FM stations can be listened to with a good system within the transmitting range of your FM 10...

Page 51: ...be set so that the audio level meters read as follows 88 1 MHz to 92 9 MHz 6 on meter 93 1 MHz to 99 9 MHz 0 on meter 100 1 MHz to 107 9 MHz 3 on meter 2 Audio Connection Hooking up an audio source to...

Page 52: ...responsibility in accordance with Part 15 of the FCC Rules to ensure that this operation does not cause interference to your neighbors EXPERIMENTAL BROADCASTING PROJECTS To use the FM 100 successfully...

Page 53: ...ieve it is worth the effort to calculate the length for your exact frequency using the simple formula of Length of one side in feet 234 Frequency in MHz If the dipole is installed vertically the end c...

Page 54: ...n show your FM 100 and this book to a licensed radio engineer and negotiate with that person for a safe installation which will feed your signal through interior wiring of your home or building Do not...

Page 55: ...air This will prevent the audio level of your voice varying every time you come on 3 Use the MIC button to toggle between on and off Turning on AUTO AGC 1 Press the AUTO AGC button when the MIC ON LE...

Page 56: ...Finally we urge all of our overseas customers to observe the regulations of their own national telecommunications authorities In all instances compliance with FCC rules in the operation of what the F...

Page 57: ...ent complying with the regulations in effect prior to June 23 1989 2 It is the sole responsibility of the builder user of any FM broadcast band device to research and fully avoid any and all interfere...

Page 58: ...FM broadcasting station or to use it for any other non interfering practical application d FCC Rule 15 5 General conditions of operation b Operation is subject to the conditions that no harmful interf...

Page 59: ...fined as a maximum field strength of 40 V per meter measured at a distance of 15 meters The June 1989 revised rule specifies a maximum of 250 V per meter but measured at 3 meters from your antenna Bot...

Page 60: ...tricts such factors as transmitter power or antenna height which cannot really limit the possible range of a transmission under good conditions By restricting the maximum field strength at a specific...

Page 61: ...may have set up a special antenna to enjoy Calibrated field strength meters such as described in the ARRL Radio Amateur s Handbook can detect signals down to about 100 microvolts To measure RF field s...

Page 62: ...n IMMEDIATELY 6 If you are contacted by the FCC regarding use of this device cooperate fully and promptly 7 Do your own homework and research to understand and comply with present and future FCC rulin...

Page 63: ...ntentions NOTICE The radio frequency intentional radiator device which may be constructed from kit parts supplied by us is intended and designed by Ramsey Electronics Inc to conform to applicable prov...

Page 64: ...not require licensing either amateur or commercial To provide more personal and club radio learning opportunities and to cut down on administrative costs today s FCC permits far more non licensed act...

Page 65: ...much 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...

Page 66: ...ly and Instruction manual for RAMSEY MODEL NO FM 100 REQUIRED TOOLS Soldering Iron Ramsey RTS06 Radio Shack RS64 2072 Thin Rosin Core Solder Ramsey RTS12 RS64 025 Needle Nose Pliers Ramsey RTS05 RS64...

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