General - HP 5254C Operating And Service Manual

Model 5254C
Section
III
SECTION
III
OPERATION
3-1.
INTRODUCTION.
3-2.
The Model 5254C Frequency Converter increases
the
range
of
an
HP
Electronic Counter to.
15
through
3.
0
GHz
(150
through 3000 MHz).
As
a general
rule
to
measure
frequency,
always
start
with
the
Mixing
Frequency
Control below
.
2
GHz
and
tune
upward
in
frequency
to
obtain
first
response and
tune for a
maximum
reading
in the
green
portion
of
the meter
scale.
The
input
frequency
is
the
sum
of
the
counter
reading
and
the
dial
frequency
reading. This proce-
dure
will
be
valid
whether there are responses
in
1,
2,
or
3
consecutive
harmonic
reference frequencies;
see
Figure 3-1.
If
the input signal level
to
the con-
verter
is
high, the second, third
and
other
harmonics
of this
signal
may
be generated. Therefore,
tuning
Mixing Frequency Control
from
the
low end
upward
will
enable
the input
fundamental frequency
to
be de-
tected
before
its
harmonics.
In the
5254C, harmonics
of
the
reference-frequency
signals are
held
to
such a
low
level that
regardless
of
input signal
level, their
mixing effects are
not
observable, avoiding possible
ambiguity. Figure 3-1 provides a step-by-step pro-
cedure
to
be used
for
measurement
of
frequencies
from
.15 to
3.
0
GHz
(150
MHz
to
3000 MHz).
The
only ex-
ception
is if
the first response occurs
at
•
15
GHz
or
.
25
GHz. To
avoid possible ambiguity
in
these cases,
start
from
above
.
45
GHz
and
tune
downward
in
fre-
quency
for the first
response and
subtract
the counter
reading
from
the
dial
frequency
for the frequency
of
the input signal.
Note
If
the input
frequency
is
known
approximately,
the
Mixing Frequency
Control can be
set
a
hundred megahertz below
the input signal.
Tune
up
for the first
response and add
the counter
reading
to the dial frequency.
3-3.
CONTROLS
AND
INPUT.
3-4.
GENERAL.
The
function
of
the front panel con-
trol,
meter, connectors, and
retaining
screws
are
discussed
in
Paragraphs 3-5 through
3-8.
3-5.
INPUT CONNECTOR.
Signal
input,
50
ohms
in-
put
impedance,
50
mV
(-13
dBm
in
50
ohms)
to
1
V
rms
(+13
dBm
in
50
ohms)
into
Type
N
female
connector.
3-6.
MIXING
FREQUENCY
SELECTOR.
Calibrated
from
.
2 to
3.
0
GHz
(200
MHz
to
3000 MHz),
this
con-
trol
tunes
the internal cavity
to
select a
harmonic
of
50
MHz
to
be heterodyned with
the
INPUT
signal.
3-7.
LEVEL
INDICATOR METER.
The meter
circuit
continuously monitors
the level of the
difference fre-
quency
output
of
the
converter
to
the counter.
When
meter
reads
in the
green
portion
of
its
scale,
INPUT
signal
amplitude
is
adequate
for
accurate frequency
measurement.
3-8.
AUX OUT CONNECTOR.
The
1
MHz
to
50
MHz
video amplifier output appears
at
AUX OUT BNC
type
connector.
3-9.
MAXIMUM
INPUT VOLTAGES.
3-10.
Damage
to
the converter
may
result
if
an
ac
signal
greater than +20
dBm
in
50
ohms
(2.2
V
rms)
or a dc voltage greater than 100V
is
applied
to
the
converter
INPUT
connector.
3-11.
FREQUENCY MEASUREMENT WITH
AMPLITUDE
LESS
THAN
50
MV
RMS.
3-12. The
front
panel
level
indicator
meter
indicates
in
the green portion
of
its
scale only
when
converter
Table
3-1. Frequency
Resolution
INPUT SIGNAL FREQUENCY
=
2.4911223344
GHz
MIXING
FREQUENCY CONTROL
set to
2.
45
GHz
Time
Base
Setting
Counter
Display Measurement
Resolution
.1
jl
s *(no display)
1 /IS
4
1
.
MHz
2.
4 9
1
GHz
10
/is
4.11
MHz
2.
4 9
1 1
GHz
.
1
ms
4 1.1 2
MHz
2.
4 9
112
GHz
1
ms
41122
kHz
2.
4
9
1 1
2 2
GHz
10
ms
4
1 1
2 2.3
kHz
2.4
9
1
1
2
2
3
GHz
.
1
s
4
1
1
2
2.3
3
kHz
2.
4 9
1 1
2 2 3 3
GHz
1
s
4
1 1
2
2.
3 3
4
kHz
2.
491
1
2
2334
GHz
10
s
1 1
22.3
3 4 4
kHz
2.491
1
223344
GHz
3-1