Alan Peake wrote:
Hi all,
I'm looking for the element values of the 2Q4 phase shifter as
described in the 1992 ARRL Handbook.
Alternatively, can anyone recommend an active (analog) all-pass that
would give the same or better results. I have some precision capacitors
so that's no problem.
Thanks,
Alan
VK2TWB

These days the way to do it would be to use a DSP. If this is for
a receiver the DSP would have two A/D converters and a single D/A
unit. The DSP would combine the two quadature signals and apply
bandwidth filtering. The quadature RF drive to the mixer would
come from a DDS circuit with both sine and cosine waveform
outputs (AD9853/54).

For a transmitter the DSP would have a single A/D and two D/A
stages, and would split the audio into two quadature signals
after applying bandwidth limiting and compression filtering.

Having said this, I wish I knew how to write the required DSP
software! However I'm sure there are some reading this list
with the required skill (talent?). (My software experience
lies in other areas, such as embedded controllers, NOT
math with imaginary numbers!).