Updated July 22, 2021

Welcome to the Hagerty Radio Company web-site.

I would like to show you my work on direct-digital VFOs (variable-frequency oscillators). A direct-digital synthesizer (DDS) utilizes a high-speed, computational integrated circuit to generate precise, stable radio signals.

New! Rotary-Switched Overtone Display Software For Valiant 1 & 2
*For this option, please add $30.00 to the kit price.

WA1FFL's talk at the Boxboro Convention, 8/25/2012

VFO Driver Amp Article (published in CQ, June 2011)

New- pc board for control switches and encoder.
All other parts included with kit. Fits BOTH detente and non-detente (Bournes EM14) encoders


An Attractive and Functional Enclosure (Rotary Switched Version)
built by Ken Miller, K6CTW

Here is a beautiful enclosure for the VFO built by Dennis B. Adamson, K8MSC, which includes all switches and functionality

Another beauty built by Tom Noel, KC8JW


Jim's Direct-Digital 'Boat-Anchor!'
See the June 2011 issue of CQ.

Here is the VFO buffer amplifier kit assembled, showing the output transformer winding detail.
Easily meets the drive requirements for the Hallicrafters HT-40, E.F. Johnson (Adventurer, Challenger and Viking 1 & 2), Heathkit DX-40, Millen 90800,
and many others.

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

Updated VFO Circuit Board, Showing Ultra-Tough LT1086 Linear Regulators.


Driver Amplifier Kit for Tubes
I now have pc boards for the June 2011 CQ article, as well as a parts kit with instructions for the amplifier kit to drive vintage tube rigs. Price is $44.00 plus $5.50 shipping Click Here to Order

Complete VFO kits with displays available for $160.00 plus $15.00 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