DIY RF Transmitter Circuit, crystal controlled

DIY Transmitter Bug - VHF, FM Crystal Controlled

Pete Zenners Radio Transmitter Circuit - XMT Modification

DIY Radio Transmitter Bug - VHF, FM Crystal Controlled - XMT

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Crystal Controlled 125mW - 150 To 165 Mhz, VHF / FM Subminiature Transmitter Bug
Resistors: 1/4 Watt
R1 = 10K
R2 = 1 MEG
R3 = 10K
R4 = 1 MEG
R5 = 2.2K
R6 = 47K
R7 = 10K
R8 = 470 Ohm
R9 = 33K
R10 = 4.7K
R11 = 10 Ohm
R12 = 10 Ohm
R13 = 470 Ohm
R14 = 10 Ohm
R15 = 22 Ohm
RM1 = 150 Ohm
Capacitors: - Disc Or Electrolytic (
Electrolytic Shown with +/- )  All Low Voltage
C1 = .05
C2 = .001
C3 = .05
C4 = 220 MFD
C5 = .01
C6 = 100 pf
C7 = .01
C8 = 2 to 22 Pf Trimmer ( Adjustable ) Small Surface Mount Type
C9 = 2 to 22 Pf Trimmer ( Adjustable ) Small Surface Mount Type
C10 = .01
C11 = .01
C12 = 2 to 22 Pf Trimmer ( Adjustable ) Small Surface Mount Type
C13 = .001
C14 = 12 to 70 Pf Trimmer ( Adjustable ) Small Surface Mount Type
C15 = 2 to 22 Pf Trimmer ( Adjustable ) Small Surface Mount Type
Transistors -  Digi-Key Electronics
Q1, Q2, and Q3 - All 2N3904 - NPN
Q4, Q5  2N3866 - NPN
MIC:
Electret Mic. Element. Most any electret element will do. Digi-Key
Electronics does sell some very small sensitive ones.
VR:
NTE-613 Varactor Diode or a suitable replacement.
ON/OFF Switch:
Any, On / Off Switch Will Do - connecting the + side of the 9 volt
battery to the circuit
BATTERY:
9.0 Volts D.C. The Negative Side Of The Battery Connects To The
On/Off Switch to ground
Antenna:
18 Inches of small flexible stranded wire
L1:
20 1/2 Tight Turns of # 30 Magnet Wire Wound tight on a  Digi-Key
Electronics  3368K-ND Fiber Washer. The Inductance of this coil is
.150 uH
L2:
13 1/2 Tight Turns of # 24 Magnet Wire Wound tight on a Digi-Key
Electronics 3368K-ND Fiber Washer. The Inductance of this coil is
.067 uH
L3:
9 Tight Turns of # 26 Magnet Wire Wound tight on a Digi-Key
Electronics 3368K-ND Fiber Washer
L4:
2 Turns of # 24 Magnet Wire Air Wound around a .155 Drill Bit.
Width between turns = 1/8"

Digi-
Key Electronics 3368k-ND Coil Form Samples
Shown Below

                Unwound                         Wound                                                  
All Components - Digi-Key Electronics
crystal controlled fm transmitter circuit diagram
fm transmitter circuit coil
FM Transmitter Circuit Diagram Coils
The Images displayed above are shown larger than the actual forms.
Actual Inside Dia: 0.120" (3.05mm)
Actual Outside Dia: 0.250" (6.35mm) 1/4"
Actual Thickness: 0.062" (1.57mm)
XT1: ( CRYSTAL )
This Circuit was a pure Accident - But The Damn thing works, and works great! It functions with
virtually any crystal you insert into it. I designed this unit for a young kid on a Task Force down in
Georgia, and accidently - thru a mistake - prototyped it with the wrong crystal. 
I started plugging various crystals into it, tuning the unit up, and then listening to it's output on a
scanner. The quality was great and you only need experiment with it.
With various Digi-Key Electronics  CA-301 Barrel Crystals and several Junk Box Crystals - Here
are some of the end frequencies ( Transmit ) I came up With:

50.0 Mhz Xtal = Transmitted at 166.953 Mhz. 49.8 Mhz Xtal = Transmitted at 166.430 Mhz. 55.0
Mhz Xtal = Transmitted at 165.160 Mhz. ( Junk Box Crystal - 143.7640 Mhz ) = Transmitted at
164.116 Mhz. 46.0 Mhz Xtal = Transmitted at 153.568 Mhz. 42.0 Mhz Xtal = Transmitted at
154.224 Mhz.

In All Cases, when tuned - the output was measured @ 2.5 Volts RF into a 50 Ohm Load - Or an
actual RMS Output of 125 Mw