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10MHz LOCAL OSCILLATOR
10MHz local oscillator. Under
development
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The
10MHz local oscillator design is a combination of G3XBM
designed local oscillator used for a similar 137kHz transverter and an ARRL Hand Book's
local oscillator design for a 160m band transverter. The success of
the this 10MHz oscillator will also be the used for a future 137kHz transverter.
Fig 1 Schematic of the
10MHz crystal lock oscillator and buffer stage. This circuit is
subject to further development.
Component
details
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XTAL
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XTAL 10MHz Fundamental
HC49U
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Q1
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Transistor - 2N3904
TO-92
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Q2
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Transistor - 2N3904
TO-92
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R1
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Resistor 100k 0.25W
Carbon
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R2
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Resistor 33k
0.25W Carbon
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R3
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Resistor 470
0.25W Carbon
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R4
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Resistor 10k 0.25W
Carbon
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R5
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Resistor 4k7 0.25W
Carbon
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R6
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Resistor 100 0.25W
Carbon
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R7
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Resistor 100 0.25W
Carbon
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C1
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Capacitor - trimmer 5
- 60pf (35pf)
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C2
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Capacitor - Ceramic -
100pf
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C3
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Capacitor - Ceramic -
100pf
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C4
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Capacitor - Ceramic -
33pf
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C5
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Capacitor - Ceramic -
100nf
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C6
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Capacitor - Electrolytic
- 47uf 50v
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C7
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Capacitor - Ceramic -
100nf
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L1
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FT50-43 Toroidal
core Amidon PN# FT-50-43
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L2
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FT50-43 Toroidal
core Amidon PN# FT-50-43
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The two RF transformers are wound per
Fig 2 & 3 winding details of 10turns of Bifiliar and Trifiliar
windings on a FT50-43 Toroidal cores.
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Fig 2
L1
winding details for the matching transformer
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Fig 3
L2
winding details for the splitter transformer
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Photo 1 Assembled L1 matching transformer
Photo 2 Assembled local
isolator and buffer circuit.
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last revised 05 May, 2025
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