Description:
This synthesizer was
designed to drive a high performance HF (Shortwave Receiver)
receiver, but it has applications to any HF radio in the DC
to 50 MHz band. Low phase noise and reference feedthrough
were also design goals. The design is fully self contained
and utilized a low cost shielding arrangement that
eliminated the need for costly custom shields. Using a
clever AC CMOS gating arrangement the 50 - 100 MHz VCO is
divided and filtered to cover the full 12 - 40 MHz range. A
PIC Microcontroller controls the programming and reads a
panel mounted rotary encoder and drives a Vacuum Fluorescent
Display (VFD). Power is provided from a simple UL approved
Wall Wart power supply. A low cost double sided board was
utilized to keep manufacturing costs down.
- Low cost and high
performance by using standard RF parts, clever use of AC
CMOS and standard mechanical enclosures.
- Fully self contained
with PIC Microcontroller driving a VFD display.
- Single supply
operation.
- Reference spur
suppression > 85 dBc.
- Harmonics > 40 dB
down.
- Phase noise of 122 dBc /
Hz at 10 kHz offset.
- 11 dBm output
power.
- Self contained low
noise, low drift, crystal reference oscillator.
- RF and PSpice
simulations used to verify and optimize the VCO
design.
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