HP 8340b User Manual

The
YIG
tuned
filter
is
a
tunable
bandpass
filter.
It
is
tuned
to
the
RF
output
frequency
by
the
SYTM
coil
drive-current
(supplied
by
the
A28 SYTM
driver).
The
filter
bandpass
frequency
is
determined
by
a
small
YIG
sphere
whose
resonant
frequency
depends
on
the
strength
of the
surrounding
magnetic
field. The
magnetic
field
is
established
by
an opposing
pair
of
electromagnet
coils.
Changing
the
current
through
the
coils
changes
the
magnetic
field
strength,
and,
consequently,
the
bandpass fre¬
quency.
Typically,
the
bandcross
is
±12
MHz.
A14 HIGH BAND POWER
AMPLIFIER
The
A14
high
band
power
amplifier
is
a
GaAs
FET (gallium
arsenide
field
effect transistor)
that
covers
the
2.3
to
7.0
GHz
frequency
range.
The amplifier
provides
approximately
26
dBm
output
power.
The
small-signal
gain
is
typically
25
dB,
but
at
maximum
leveled
output,
the amplifier
can
be
10
dB
into
compression.
A
7.0
GHz notch
filter
reduces
harmonics out
of
the amplifier.
This
filter
is
switched in
when
the
amplifier
operates
below
4.5 GHz.
A15
LOW BAND LOW
PASS
FILTER
The
A15
low
pass
filter
attenuates harmonics from
the
3.7
GHz oscillator
to
minimize
unwanted
mixing
products produced
in
the
A17
low
band
mixer.
A16
HIGH
BAND MODULATOR/SPLITTER
The
A16
modulator/splitter
divides
the
YIG
oscillator
output
into
three paths:
•
The
low
band
output provides
LO
drive for
the
low band
mixer.
•
The
high
band
output
feeds
the
high
band
amplifier.
•
The
third
output
feeds
the AUX
OUTPUT
via
an
internal
coupler.
A17
LOW
BAND
MIXER
The
A17
mixer
mixes
a
fixed
3.7
GHz
signal
with
the
swept
3.71
to
6.0
GHz
YO
output,
producing
the
0.01
to
2.3
GHz
RF
output
of
low
band.
A
3.7
GHz directional
filter
(before the
single balanced
mixer) and
a
2.75
GHz
low
pass
filter
(at the
output)
minimize
unwanted
mixing
products.
The
swept
YO
output,
after
passing
through
the
A16
modulator/splitter,
acts
as
the
local
oscillator
signal
for the
mixer.
Conversion loss
is
approximately
9
dB
at
1
GHz
HP 8340B/41B
RF
Section
Theory
of
Operation
H-5

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English