via this auction
"A frequency shifter is not a pitch shifter, it shifts each harmonics of a sound by a frequency separately up and down. With the rarely available external reference input one can shift each harmonic by each harmonic frequency in the reference frequency (which itself is not heard directly).
The unit has two separate built in voltage controlled reference sine wave oscillators, one each for the frequency shifter and balanced modulator sections.
One also has the option of using any external wave for both sections carrier and modulator bypassing the internal oscillator. I'm pretty sure the 285e is the only frequency shifter module currently in production that can frequency shift the input wave with another input wave. The only other module I know of that did this was the (as far as I know) no longer produced Serge External Carrier Frequency Shifter, one of their most expensive "modules".
Firmware version 30.2 (current). Includes mounting screws.
Manufacturer Description:
The top section of the dual-function 285e performs frequency shifting; up and down outputs are simultaneously available. The reference frequency can be externally applied or internally generated; the latter can be voltage-controlled and modulated using FM.
The bottom section is independent, and functions as a balanced modulator of the applied signals. The degree of modulation is voltage-controlled, and the reference frequency can be internally generated or externally applied, as with the frequency shifter. A separate audio output is dedicated to classic ring modulation, a subset of balanced modulation.
All settings of the 285e can be stored and recalled as part of a preset using the 225e or the 206e Preset Manager"
