Phasing Strip; Figure 131. Audio Phasing Section Schematic - NORCAL NC2030 Manual

Phasing strip

Figure 131. Audio phasing section schematic

The phasing strip gives opposite side band rejection. The I and Q outputs of the audio preamplifier are
passed into the phasing strip. The phasing strip causes one leg to be shifted an additional 90 degrees
compared to the other leg. Thus instead of I and Q being 90 degrees apart from each other, on the USB,
the two halves of the phasing strips end up being 180 degrees apart from each other and when summed
across the two 2K output resistors, cancel each other out. Conversely, on the LSB, the two outputs are
now in phase and simply add to each other.
The phasing strip has two adjustment pots to properly align the opposite sideband suppression. One pot
adjusts the rejection at the low frequency end (300 Hz), while the other adjusts the rejection at the high
frequency end (700 Hz).
After the phasing strip has been aligned, the opposite side band will be rejected a minimum of 45 db,
with much of the bandpass having 50 to 55 db of opposite sideband rejection.
The phasing strip has no audio gain.
Norcal NC2030 v5 12-18-05
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