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Formulas for Cable
Length Maximums
Figure 3-2
NOTE
The maximum LO source frequency required when driving the HP 11970x
waveguide mixers is 6.11 GHz. The two cable lengths (L
affected by this maximum frequency. Refer to the diagram below.
L
, L
, L
Cable Lengths, Example
S
R
T
The maximum length of the LO cables (L
a. the LO power required by the mixers
b. the LO output power available from the HP 85309A across the LO
frequency range (3 to 6 GHz)
c. the loss through other microwave components in the LO path.
Test and reference cables must be the same length.
The output LO power of the HP 85309A is normally greater than +20.8 dBm
between 3 and 6 GHz. The mixers require a nominal +16 dBm (+14 dBm
minimum). The difference between these two LO power levels (+ 20.8 dBm
and +16 dBm) determines the maximum loss of the test and reference path.
General Information
Maximum RF Cable Lengths
and L
R
or L
) is a function of:
R
T
HP 85325A Operating and Service Manual 3-7
) are
T
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