27-04-2012, 10:33 AM
Google Jackson Brothers - I believe their successors still supply variable capacitors of both air-spaced and solid dielectric type, so I imagine they'll have a differential type. I have one, retrieved from an early 1930s homemade set. I believe I could also lay hands on an air-spaced low capacity type as well (I'd have to rummage).
Of course you don't need a differential for reaction purposes - a minor mod to the circuit will allow the use of a 'standard' component. The differential design was supposed to prevent (or limit) reaction chasing, the effect that forces slight retuning as reaction is adjusted.
-Tony
Of course you don't need a differential for reaction purposes - a minor mod to the circuit will allow the use of a 'standard' component. The differential design was supposed to prevent (or limit) reaction chasing, the effect that forces slight retuning as reaction is adjusted.
-Tony
