Some guidelines for user input cabling are:
• For best high-frequency performance, user cabling should have at
least two braided shields or one braid and a foil wrap.
• Always use shielded coaxial cables with the characteristic
impedance of the multiplexer used (50Ω or 75Ω). Keep cables as
short as possible, especially in high-frequency circuits or pulse
circuits where a rise/fall time of <50 nsec is critical.
• Long cables can add delay time which can cause timing problems.
All test equipment, such as counters, spectrum analyzers, and
oscilloscopes, must be terminated in the characteristic impedance to
minimize reflection loss.
• To maintain low dc offset voltages, cables should have copper center
conductors, not copper-clad steel. RG-233/U cable is recommended.
Table 2-1 lists Hewlett-Packard BNCcables which meet these
guidelines.
Table 2-1. Hewlett-Packard BNC Cables
Type Length Part Number
50 Ω coaxial 30 cm (12 in)
61 cm (24 in)
122 cm (48 in)
8120-1838
8120-1839
8120-1840
75 Ω coaxial 30 cm (12 in)
61 cm (24 in)
5062-6452
5063-0061
Chapter 2 Configuring the HP E1366A/E1367A RF Multiplexers 19