Thank you for visiting my amateur radio website. My name is James Hagerty and I have been licensed since 1965. I am an electrical engineer with 35 years’ experience. Updated April 1, 2011

See you at Dayton 2011, Booth #351

Jim's Direct-Digital 'Boat-Anchor!' See the June 2011 issue of CQ,
or visit us at Dayton Booth #351 (May 20-22) for details.

My current project is a Direct-Digital VFO (variable-frequency oscillator) using the Analog Devices AD9951.

Circuit Board Close-Up.

Complete VFO kits with displays available for $145.00 plus $5.00 shipping 
*** Ordering information for the VFO Parts Kit is described here.

Click for New Spectral Plots     10 kHz Resolution    1 kHz Resolution

This circuit, as well as an accompanying article is published in QEX for May/June 2008. (1.4mb PDF)
Reprinted with the permission of the ARRL. Copyright ARRL.

The VFO features include:

  1. Full Coverage of 100 kHz through 30 MHz.
  2. Improved Spectral Purity Over Past Designs.
  3. Flash EEPROM Memory Storage of 16 Frequency Configurations (Expandable to 32).
  4. RIT (Receive Incremental Tuning), +/- 10 kHz in 10 Hz Steps.
  5. CAL Routine (1 Hz step increment/decrement of carrier) to Compensate for Clock Oscillator Error.
  6. Transmit Offset {Selectable: plus or minus CW (700 Hz) or SSB (1.5 kHz)}; can be tied to the keying line or enabled separately.
  7. Frequency Tuning Steps of 1 Hz, 10 Hz, 100 Hz, 1 kHz, 10 kHz, 100 kHz, and 1 MHz, selectable by rotating the tuning encoder while holding down the “step” switch.

The accompanying photos will give you an idea of what the VFO board looks like all ready to go. As design updates are completed, important applications information will be available on this site. I now have a revised parts list, as well as several new filter designs to choose from for the pre-filter (between the DDS output and the input to the amplifier stage).

Clean Output Waveform at 21 MHz