I have an old radio that uses a permeability variable inductor (~ 1uH - 3-uH) within a vacuum tube VFO (PTO). it offer very smooth, precise tuning over a full 360 rotation that covers 100 kc band spread. I want to replace the tube oscillator with a DDS but retain the permeable inductor to retain the old design as the electromechanical tuning interface. The new DDS/PTO would cover the HF band between 1.8 - 2MHz and that then goes into a mixer stage.
I am looking for a circuit concept that would allow the inductor range of 1 - 3uH to linearly vary a voltage from e.g., 0 -5vdc TTL to be read by an Arduino controlled DDS. The perm inductor is in a shielded, temp compensated enclosure within the radio. Any advise where to start would be much appreciated.
Jerry
I am looking for a circuit concept that would allow the inductor range of 1 - 3uH to linearly vary a voltage from e.g., 0 -5vdc TTL to be read by an Arduino controlled DDS. The perm inductor is in a shielded, temp compensated enclosure within the radio. Any advise where to start would be much appreciated.
Jerry