Philips PM 6670 Operating Manual page 4

Input and output
specifications
Inputs A and B
Frequency range:
Decoupled: 0. .120MHz
AC coupled: 50 Hz . . .120 MHz
Rise time: Approx. 4 ns.
Sensitivity:
Decoupled: lOmVprps sine wave or
30mVpp(0...75MHz).
20mVrms sine wave or
60mVpp(75...120MHz).
AC coupled: lOmVrms- -lOOrnVrms sine
wave(50 Hz...75MHz).
20 mVcnig... 100 mVrrps sine
wave(75...120MHz).
Attenuation: x 1 /x 10 fixed.
For frequency related measurements, tfie
fixed attenuator can be used in combina
tion with the continuously variable attenu
ator x1. .. xlO (AC coupled position).
Noise immunity/tiysteresis band:
Decoupled: approx. 20mVpp/200mVpp.
AC coupled: approx. 20mVpp. . .2Vpp.
Dynamic input voitage range:
Decoupled: 30mVpp...5Vpp/
300 mVpp... 50 Vpp.
AC coupled: lOmV^ms - -SVrms/
100 mVrms 20 Vrms-
Trigger levei:
Decoupled: -2.5V...-1-2.5V/
-25 V...-1-25 V.
AC coupled: fixed OV; level control acts
as continuously variable attenuator, which
is more suitable for frequency related
measurements.
Trigger level output, not available on PM 6670:
Set trigger voltages -2.5 V. . .-1-2.5 V, avail
able on 1 mm jacks at the front for moni
toring of set trigger level.
Trigger indicators, not available on PM 6670:
Tri-state LED trigger lights to indicate
trigger status:
On: trigger level is too low.
Blinking: triggering occurs, input signal
crosses hysteresis band.
Off: trigger level is too high.
Coupling: DC/AC
Impedance: Approx. 1 MOhm//35pF, inde
pendent of sep/com switch position.
Ct^annel input: Separate A and B or
common A.
Noise filter: Switchable 50 kHz Low pass
filter in channel A. Noise suppression
approx. 40dB at 1 MHz.
Maximum voltage wittiout damage:
DC; 300 V.
AC; 260 Vrms al -440 Hz declining to
12Vrms a' -1 MHz (in ATT x 1 position),
260Vrms (in ATT x 10 position).
input C, PM 6672 only
Frequency range: 70MHz. ..1GHz.
Operating input voitage range:
15mVrms. .12Vr,ms( 70 MHz...800 MHz).
2o mVpms... 12 Vrms (800 MHz... 1 GHz).
Impedance: 50 Ohm nominal; VSWR <2.
Coupling: AC.
AM tolerance: 98%, minimum signal must
exceed minimum operating input voltage.
Maximum voitage without damage: 12 Vrms;
overload protection with PIN diodes
Ext. reference and
Ratio input (channel D),
not available on PM 6670
Frequency range: 1 kHz.. .10MHz.
Sensitivity: 500mVrms
Impedance: Approx. 2 kOhm
Coupling: Ac
Max. voltage without damage: 25 Vrms
Note: As external reference frequency,
only 10 MHz will give correct decimal point
and unit indication. With the optional
frequency multiplier PM 9697 references
of 1 and 5 MHz can also be accepted.
Internal standard output
(channel D),
not available on PM 6670
Crystal frequency: 10 MHz.
Output level: LS-TTL compatible.
Output impedance: Approx. 400 Ohm.
Coupling: DC.
Overload protection: Short-circuit proof.
Ext. arming/Freq-avg/
Reset (channel E),
not available on PM 6670
A 3-position rear panel switch gives
choice of external control over:
ARMING: In this position, the counter is
prevented from starting a new measure
ment when input E is high. A high-to-low
going pulse arms the counter to start a
new measurement.
Note: Arming not applicable in COUNT A,
manual mode.
FREQUENCY AVERAGE: Frequency
measurements (max. 100MHz) and period
measurements are interrupted when
input E is high. The measurement is con
tinued again when input E is low. Each
individual frequency sample must contain
at least 20 pulses (FRED mode) or 2
pulses (PERIOD mode).
The effective measurement time (defining
resolution and accuracy) is the sum of
external gate times that occurs during the
selected measurement time.
EXT. RESET-START: Electrical reset,
equivalent to the front panel RESET push
button. (See HOLD and RESET). Counter
is reset when input E goes high. A new
measurement can be made after input
E has returned low.
input ieveis:
High: '^2\/.
Low: =£0.5V.
Input impedance: Approx. 2kOhm.
Max. input voltage without damage: ±25 V
Minimum puise duration:
Arming and frequency avg: 500 ns.
External reset: 200>js.
Gate monitor output (rear),
not available on PM 6670
The gate status monitor output permits
observation on an oscilloscope of the
measured time interval and the trigger
hold-off time (PM 6671 only).
Output level:
Main gate open: approx. 0.4 V.
Hold-off active: approx. 1.2 V.
Main gate closed: approx. 2.5 V.
Output impedance: Approx. 1.5 kOhm.
Delay: Internal delay between actual trig
gering and gate monitor output is approx.
150 ns.
Overload protection: Short circuit proof.
Auxiliary functions
Measuring time
The measuring time is "continuously" vari
able (33 steps/decade): 10ms. . .96s. with
clear setpoints at 10ms, 100ms, Is, 10s
and 96s. Selected measuring time is dis
played, without any delay, when depres
sing the measuring time control.
The actual measuring time equals the
selected measuring time plus the time
needed to synchronize the measurement
with an integer number of cycles of the
input signal (Reciprocal measurements
are synchronized with multiples of 10 in
put cycles).
In the FREQUENCY AVERAGE mode,
the measuring time can be externally con
trolled to make burst frequency average
measurements.
Hold-off PM 6671 only
With trigger hold-off activated, the counter
ignores re-triggering (channel A) or stop
triggering (channel B) during the set
hold-off time. The hold-off time can be
digitally measured by pressing CHECK.
Applicable in all time modes.