User`s guide

21
increasing the system cost and
complexity. The HP 71500A
solution is much simpler,
because it directly provides
RF-IF or IF-RF measurements
without additional components.
HP 11770A Link
Measurement Personality
This personality provides the
HP 8590 E-series spectrum
analyzers with group delay
measurement capability very
similar to an MLA. This solution
can measure devices from 300
KHz to 2.9 GHz; it is not limited
to 70/140 MHz IFs as with
a conventional MLA. Using two
spectrum analyzers with
this personality, RF frequency
translating devices can be
measured relatively inexpensively.
The link analyzer personality
has one potentially serious
limitation — it cannot measure
devices that perform a
frequency inversion (i.e., the IF
sweeps downward in frequency
as the RF is swept upwards).
This can occur when measuring
downconverters such as direct
broadcast satellite (DBS) tuners
that use high-side LO mixing
(LO > RF). The MTA does not
have this limitation as it is
tuned independently from
the source.
Summary
For microwave measurements
of frequency converters with
internal LOs, the HP 71500A is
the highest performance
solution, especially when FM
group delay is required. For RF
measurements, the choices are
greater. For many applications,
lower cost solutions will suffice,
such as an SNA, or two HP 8590
E-series spectrum analyzers
with the link analyzer
personality. The HP 71500A
solution can fill certain niches
such as when FM group delay of
a frequency inverting device is
needed, or where the instrument
can provide additional
measurements such as time
domain pulsed-RF profiling, or
dynamic AM-to-PM conversion
measurements.