Henning,
The 6db pads are there to try and tame the wily DBM.? They provide a optimized
match to the ports for best possible performance.? Also because the 5351 is not?
a 50ohm output devices as it was initially designed to drive digital things.
Yes that means the diodes are not turned on "hard". That does two things,
makes the mixing process less linear and more subject to having the other
signal also interact with the diodes to alter their instantaneous current (undesired).
Now the signal happen to be very square as in on time is equal to off time.
In the frequency domain it means even harmonics are weaker than the
odd harmonics.??
However the signals seen at the diodes are square as the leakage inductance
of the transformers is small as a result of tight coupling (twisted wire) so the?
extrapolating the wave?shape?at the diode being a factor is not true.? its limited?
current flowing?in the?diodes interacting with the fairly high current of the signal
that causes some of?the havoc.
Combine that with the very nature of sampled signals (yes nyquist) we get a
lot of mush at the output.? Its very simple looking device but anything but simple
in operation.
Allison
