Crystalcontrolled147.460MHzFMtransmitter

Crystal controlled 147.460 MHz FM transmitter
  The XFM1 transmitter is a crystal controlled tone modulated FM transmitter designed for model rockets but suitable for wildlife, balloons and many other applications requiring a small, frequency stable FM transmitter. Use this transmitter with a scanner or 2 meter amateur radio receiver. Transmitter ground range is approximately 400 yards (5 feet above ground) . Field tests were done with a ICOM IC-W32A transceiver with 0.16 micro volts of receiver sensitivity through the standard 8 inch antenna. Air to ground transmissions can improve range significantly as will a directional high gain antenna or a more sensitive receiver.General Specifications:
  Frequency: 147.455 to 147.460
  Mode: FM
  Size: 2 .75 "x 0.5"
  Weight: 8 grams (.3 oz) including battery
  Range (ground): 400 yards with counterpoise
  Frequency control: Crystal
  Battery life: 3 days (two CR1632 batteries in series)
  Receiver Type/requirements: FM, 144.455 - 147.460 MHz., 0.16microvolts sensitivity or better
  Receiver Antenna: directional antenna recommended but not required.
  Other: Knowledge of radio direction findingTRANSMITTER
  The transmitter is a crystal controlled 147.460 MHz FM transmitter.The transmitter is tone modulated by a 12F675 microprocessor approximately every two seconds. A Morse code call sign ID is transmitted approximately every 30 seconds. If a call sign has not been specified it will transmit “XFM1”.The transmitter is turned off between tone bursts which greatly extends the battery life. The circuit is designed to use a low cost “computer crystal” 49.39 Mhz (3rd over tone), However, custom crystals can be used if other frequencies are desired. If other frequencies are desired a 3rd overtone series crystal can be ordered from a crystal manufacture. Microprocessor
  The transmitter is controlled by a program running border=0>
   
  
  
  Directional Beam antenna:A “beam” or “Yagi” antenna is probably the simplest and best all around choice for a directional antenna. A simple 3 element antenna can be built for about $10.00 using common materials. The sensitivity pattern shown below is when both the transmitter and receiving antenna is polarized vertically (the elements are pointing up and down). If the antenna of the transmitter are not vertical then the pattern will be different unless the receiving antenna is orientated to match the transmitter antenna. Since the transmitter antenna’s orientation is not always known some experimentation must be done with the receiving antenna. (Note that the patterns are not always as shown. They can vary depending border=0>
    Receivers
  To achieve adequate performance you will need a receiver with at least 0.16 micro volts of sensitivity. Most 2-meter Amateur (ham) radios are at least this sensitivity. Scanners may or may not be sensitivity enough.
  
  Component Side View
  
  
  
  reversed foil side
   
  2" x 0.65"
  
   foil side
  
  Transmitter parts
  Resistors
  Value
  Part number
  Supplier
  Comments
  R1
  10K 1/8 watt
  299-10K
  Mouser
  R2
  100K 1/8 watt
  299-100K
  Mouser
  Capacitors
  C1
  .001uF
  21RX510
  Mouser
  C2
  22pF
  21RD722
  Mouser
  C3
  15pF
  80-C315C150J1G
  Mouser
  two C3 (15pF caps) may be needed (see text)
  Semiconductors
  Q1
  NTE107
  526-NTE107
  Mouser
  Q2
  NTE108
  526-NTE108
  Mouser
  Crystal
  xtal
  147.460
  815-ABLS-49.152-B2
  Mouser
   49.152MHZ 3rd overtone crystal
   Inductors
  L1
  0.68 uH
  434-22-R68
  Mouser
  L2
  4 turns #22 magnet wire tightly wound on 1/8"dia.
   278-1345B
   Radio Shack
   Enamel-coated magnet wire
  Miscellaneous
  Battery
  CR1632 or BR1632
  658-BR1632
  Mouser
  PCB
   See foil pattern
  antenna & Counterpoise
  12 inch
   #20 to #24 solid conductor wire
   Just about any type of “hook-up” or phone wire
  J1
  Jumper wire
  Use trimmed off leadsource codetele147_1.asm