HP 70427A User Manual page 486

LO port, or to drive the LO port of one of the HP 11970 family of millimeter
harmonic mixers.
External Application of Millimeter Harmonic Mixers
The external harmonic mixer may be used to extend the frequency range
from 26.5 GHz to 110 GHz. The mixer requires an LO frequency of 2.4 to
6.6 GHz at +16 dBm. The mixer multiplies input frequencies between 26.5
GHz and 110 GHz with the harmonics of the stepped microwave reference
source to produce an IF between 5 MHz and 1500 MHz. If an odd harmonic
is required to produce the desired IF frequency, a bias current between –10
mA and +10 mA must be added to the IF port of the mixer. If an even
harmonic is required to produce the desired IF frequency, no mixer bias is
necessary.
Microwave Downconversion Mixer
The downconversion mixer multiplies microwave inputs between 1.5 GHz
and 26.5 GHz with the stepped microwave reference source to produce an IF
signal between 300 MHz and 900 MHz.
The mixer LO port is connected to the step reference output amplifier via the
SPDT, DC to 26.5 GHz switch connected to the step reference output
amplifier. The reference output level into the mixer is +10 dBm.
The microwave signal to be downconverted is connected to the mixer RF
Port via the two DC to 26.5 GHz attenuator/switch assemblies. The input
attenuator is used to attenuate input signals of –10 dBm to +30 dBm into the
RF port input range of –5 dBm to –10 dBm. The downconverter is usable for
signals between –10 dBm and –30 dBm, but the input attenuator must be
manually set to 0 dB attenuation. The downconverter maximum RF port
input level can be changed using the
back to the default value whenever the module is preset.
The tuning algorithm is designed to tune continuously over the 1.5 to 26.5
GHz frequency range, while minimizing the number of microwave
frequency steps required, and the frequency range of the IF signal. In
standard operation, the IF amplifier will be always be between 300 MHz and
600 MHz, except in the following cases:
at an input frequency of 1.5 GHz to 1.8 GHz, 2.1 GHz to 2.4 GHz and
25.8 GHz to 26.1 GHz, the IF frequency must be extended from 600 to
900 MHz, and
at an input frequency of 26.4 GHz to 26.5 GHz, the IF frequency must
be extended from 600 to 700 MHz.
These constraints were chosen to minimize the noise from the
HP 8662/3 RF signal generator used as the RF reference for phase noise
measurements of the downconverted IF output.
HP 70427A Microwave Deck Assembly
softkey, but will change
MIXER MAX LVL
HP 70427A/HP 70428A User's Guide 13-51
Block Diagram