Fluke PM6669 User manual

Universal Frequency
Counter
PM6669
Operators Manual

CONTENTS
SAFETY...........................................................................2
Introduction ...................................................................2
PRODUCT PRESENTATION .........................................3
General .........................................................................3
Rear View......................................................................3
Front View.....................................................................4
INSTALLATION ...............................................................5
Unpacking.....................................................................5
Voltage-Range Selection ..............................................5
Grounding .....................................................................5
Connecting External Reference....................................6
Installing Options ..........................................................6
Calibrating the MTCXO.................................................6
OPERATING INSTRUCTIONS........................................8
Using the Frequency Counter.......................................8
Battery Unit ................................................................20
Error Codes.................................................................20
GPIB-INTERFACE OPERATION..................................21
Introduction .................................................................21
What Can I Do Using the Bus?...................................21
Connecting the Controller ...........................................22
Giving the Counter an Address...................................22
Checking the Communication.....................................22
Two Ways of Programming.........................................23
Syntax .........................................................................23
Selecting Output Separator.........................................24
How to Select Function ...............................................24
Selecting Measuring-Time...........................................24
Selecting Triggering.....................................................25
Totalize Start/Stop .......................................................25
Free-Run/Triggered.....................................................25
Service Request..........................................................26
Status Byte..................................................................26
Output Mode................................................................27
Bus Learn....................................................................30
Programming Data Out...............................................30
What Happens When I Switch to Local?.....................30
Summary of Bus Commands......................................31
Programming Examples..............................................32
SPECIFICATIONS .........................................................35
Measuring Functions...................................................35
Definitions....................................................................36
Input specifications......................................................36
General Information.....................................................37
Auxiliary Functions......................................................38
Optional Accessories...................................................38
Ordering Information ..................................................40
APPENDIX 1..................................................................41
Checking the Sensitivity of Counters ..........................41
INDEX ............................................................................43
4822 872 20021
5/12-April-1995
CONTENTS Page: 1
PM 6669 - OPERATORS MANUAL

SAFETY
Introduction
Read this page carefully before you install and use the
PM 6669 Frequency Counter.
This Frequency Counter has been designed and tested in
accordance with IEC publication 1010-1, and CSA 22.2
No.231, and has been supplied in a safe condition. The
user of this instrument must have the required knowledge
of PM 6669. This knowledge can be gained by thoroughly
studying this manual.
Safety Precautions
Use generally-accepted safety procedures, in addition to
the safety precautions stated in this manual, to ensure per-
sonal safety and safe operation of the Frequency Counter.
Caution & Warning Statements
You will find specific warning and caution statements,
where necessary throughout the manual. Do not carry out
repairs or adjustments to the Frequency Counter without
reading the Service Manual, which contains the relevant
warnings for such activities.
CAUTION: Indicates where incorrect operating pro-
cedures can cause damage to, or
destruction of, equipment or other property.
WARNING: Indicates a potential danger that re-
quires correct procedures or practices in
order to prevent personal injury.
Symbols
Indicates where the protective ground lead is
connected inside the instrument. Never unscrew
or loosen this screw.
If in doubt about safety
Whenever you suspect that it is unsafe to use the instru-
ment, you must make it inoperative, clearly mark it to pre-
vent its further operation, and inform the Fluke service
Centre.
E.g.The instrument is likely to be unsafe if it is vis-
ibly damaged.
Page: 2 SAFETY
PM 6669 - OPERATORS MANUAL

PRODUCT PRESENTATION
General
The PM 6669 is a compact, high resolution, reciprocal Fre-
quency Counter which performs many functions. Anum-
ber of options are available i.e. HF-input, GPIB-interface,
high stability oscillator, and rechargeable battery for field
use.
Arack-mount kit and a carrying case are also available as
accessories.
Rear View
A) Rear feet.
B) Screws for removing the cover.
C) External-reference-input, BNC connector.
D) Voltage-range selector.
E) Power-inlet socket.
F) GPIB interface-connector (optional).
G) GPIB address-selector ( option).
10MHz 0.5-15Vrms
EXT REF INPUT
VOLTAGE
SELECTOR
PM 9604
INCLUDED OPTIONS
PM 9605
PM 9607
PM 9608B
IEEE 488 INTERFACE
TALK ONLY
ADDRESS
16 8 4 2 1
ON
OFF
SUPPORTED
FUNCTIONS:
SH1,AH1
T5,L4
SR1,RL1
DC1,DT1
E2
THERMAL FUSE IN
MAINS TRANSFORMER
A B C D E B A
F G
Figure 1 Rear View.
PRODUCT PRESENTATION Page: 3
PM 6669 - OPERATORS MANUAL

Front View
H) Large LCD-display.
J) Input-A BNC-connector.
K) Sensitivity control with dual-range push-in/pull-out
switch.
L) 50 kHz filter switch (Input-A).
M) Input-B BNC-connector (optional).
N) Power switch.
O) Reset button, doubles as Local button if the Fre-
quency Counter is equipped with an GPIB inter-
face. Starts and stops counting if the TOT A
function is selected.
P) Measuring-time selector-button. *
R) Function-selector button. *
S) Display-hold button. Freezes the display. The but-
ton is also used for storing A0.
T) Blank digits button. Blanks out one digit for each
depression of the button, from the right to the
left of the display. (No rounding off).
U) Trigger level setting button.
V) Tilting support.
* The selected function is indicated on the display. A
short press on the button moves the cursor one
step to the right. A long press makes the cursor
scroll.
FUNCTION
PM 6669
UNIVERSAL FREQUENCY COUNTER
160MHz/1.3GHz
200mVrms
10mVrms
MIN
SENSITIVITY
A
LEVEL A
TRIGGER
Ao
STORE
AA
TRIGGER LEVEL A
AUTO
EXT
REF
TOTALIZE A
STANDBY
ON RESET
LOCAL MEAS TIME DISPL HOLD BLANK DIGITS
FREQ
AFREQ BFREQ A/Ao FREQ A-Ao RPM APER ATOT WIDTH
SINGLE 0.2s 1s 10s
MEASURING TIME
DISPL
HOLD
INPUT A
10Hz-160MHz
MAX 350Vp
1M
Ω
30pF
OPTION
70MHz - 1.3GHz
MAX 12Vrms
50 Ω
START/STOP
FILTER<50kHz
INPUT B
H J K L M
N O P R S T U V
Figure 2 Front View.
Page: 4 PRODUCT PRESENTATION
PM 6669 - OPERATORS MANUAL

INSTALLATION
Unpacking
If the Frequency Counter is cold, leave it in the cardboard
box until it has reached normal room temperature.
–Lift the Frequency Counter out of the box.
–Remove the polystyrene supports.
–Unpack the Frequency Counter from the plastic bag.
–Reverse the procedure to pack.
Check List
Has the Frequency Counter been damaged in transport?
If it has, file a claim with the carrier immediately, and notify
the Fluke sales & service organization to make repair or
replacement of the instrument easier.
–Check that the package contains the following items in
addition to the Frequency Counter:
–This Operators’ Manual
–A power cable with protective earth conductor
–A Battery unit if ordered *)
–An MTCXO oscillator if ordered *)
–A GPIB interface if ordered *)
–An HF-input if ordered *)
*) Labels on the rear panel indicate which options
are fitted in your Frequency Counter.
Voltage-Range Selection
Set the Frequency Counter to the local line voltage before
connecting it. As delivered the Frequency Counter may be
set to either 115 V or 230 V. The setting is indicated on the
voltage range selector on the rear panel.
If the voltage range setting is incorrect, set the selector in
accordance with the local voltage before connecting the
power cable to the line.
Grounding
The Frequency Counter is connected to ground via a
sealed three-core power cable, which must be plugged
into a socket outlet with a protective ground terminal. No
other grounding is permitted for this Frequency Counter.
Extension cables must always have a protective ground
conductor.
PM 9604
INCLUDED OPTIONS
PM 9605
PM 9607
PM 9608B
Figure 3 Options Label on Rear Panel.
10MHz 0.5-15Vrms
EXT REF INPUT
VOLTAGE
SELECTOR
PM 9604
INCLUDED OPTIONS
PM 9605
PM 9607
PM 9608B
IEEE 488 INTERFACE TALK ONLY
ADDRESS
16 8 4 2 1
ON
OFF
SUPPORTED
FUNCTIONS:
SH1,AH1
T5,L4
SR1,RL1
DC1,DT1
E2
THERMAL FUSE IN
MAINS TRANSFORMER
Figure 4 Location of Voltage Range Selector.
INSTALLATION Page: 5
PM 6669 - OPERATORS MANUAL

WARNING: Never interrupt the protective ground-
ing intentionally. Any interruption of the
protective ground connection inside or out-
side the instrument, or disconnection of
the protective ground terminal is likely to
make the instrument dangerous.
Connecting External
Reference
If you wish to use an external 10 MHz reference frequency
source, connect it via a BNC-cable to the EXT REF INPUT
on the rear panel of the Frequency Counter.
When the Frequency Counter starts measuring, it automat-
ically detects the external reference and begins to use it.
The EXT REF indicator on the display is switched on.
Installing Options
Introduction
The options ordered at the same time as the Frequency
Counter are normally factory-installed. Other options can
be fitted when needed.
The options fit inside the Frequency Counter, but not all at
the same time: The HF-input, the high stability-oscillator
and either of the GPIB-interface or the Battery-unit can be
installed in one and the same Frequency Counter.
Calibrating the MTCXO
The MTCXO Time-base can easily be recalibrated to any
10 MHz reference. To maintain the accuracy of the
MTCXO, use a reference with an accuracy of 3*10-8.
The PM 9691 oven-enclosed oscillator used in Fluke
counters version /.5. meet this requirement, if calibrated.
Preparations
If you remove the cover when counter has been switched
on, the temperature of the MTCXO will rapidly drop about
10°C. Since the MTCXO must have a stable temperature
when calibrated you must wait an hour between removing
the cover and calibrating.
If the counter has been switched off more than three
hours, you can calibreate it directly.
Removing the Cover
WARNING: When you remove the cover you will ex-
pose live parts and accessible terminals
which can be dangerous to life.
–Make sure that the power cable is disconnected.
WARNING: Although the power switch is in the off
position, the line voltage is present on the
printed circuit board.
–Loosen the two screws in the rear feet.
–Grip around the front panel and pull the Frequency
Counter out of the cover.
Calibration Procedure
–Remove the cover from the counter.
–Allow the MTCXO to adapt the new ambient tempera-
ture. (See ’Preparations’.)
–Connect the 10 MHz reference to Input-A.
–Switch ON the counter.
–Adjust the sensitivity control so that the counter counts
properly.
–Hold down the CALIB-button, on the main printed-circuit
board in the counter, and press the Reset-button.
Loosen the two screws
using a Pozidrive No. 1 screwdriver
Figure 5 Loosen These Screws to Remove Cover.
Page: 6 INSTALLATION
PM 6669 - OPERATORS MANUAL

–Wait about 20 seconds, until the display shows
10.0000000 MHz. Now the oscillator is calibrated.
–Switch OFF the counter and disconnect the 10 MHz ref-
erence.
Fit the cover.
CALIB-button
Figure 6 Location of the CALIB-Button.
INSTALLATION Page: 7
PM 6669 - OPERATORS MANUAL

OPERATING INSTRUCTIONS
Using the Frequency Counter
CONTROL OPERATING THE
CONTROL DISPLAY GPIB-CODE
POWER, a two-position
mechanical push-button.
Pressed = ON,
Released = OFF
No control
possible but D
gives the same
settings as
after power-ON.
A short depression of
the FUNCTION key
moves the cursor in the
lower edge of the
display one step to the
right. If the key is held
depressed, the cursor
will scroll to the right
until released. When the
cursor reaches the
rightmost position it
jumps back to the
leftmost position and
continues from there.
One code for
each function,
- see below:
Move function cursor to
FREQ A FREQ A
ON
STAND-BY
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
M kHz
ums
GATE
0.
FUNCTION
FUNCTION
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
0.
Page: 8 OPERATING INSTRUCTIONS
PM 6669 - OPERATORS MANUAL

FUNCTION AND RANGE HINTS AND COMMENTS
Switches the power ON and OFF. When switched on,
the built in microprocessor switches on all segments
of the display then it runs a power-up test, checking
the measuring-logic of the Frequency Counter before
the counter starts working. This test takes about 2
seconds.
If an error is found, an error code will be displayed.
Try switching the Frequency Counter off and on
again. If error code 01 - 03 persists, call Fluke serv-
ice. Look on the last page in this manual for Phone
No. and address.
WARNING:The power switch operates on the
secondary side of the transformer. The power cable
must be disconnected from the line outlet socket if it
is necessary to completely isolate the Frequency
Counter from the line.
Error 01 = RAM memory error
Error 02 = Measuring logic error
Error 03 = Internal bus error
Error OF = Overflow in the counting registers
Selects one of the nine measuring functions available. The cursor does not stop at FREQ C if no Input-C HF-
input is installed.
Reciprocal frequency measurement of the signal at In-
put-A.
Range:
0.1 Hz to 16 MHz (SINGLE measuring-time)
1 Hz to 160 MHz (0.2, 1, and 10 s measuring-time)
If the signal is sine shaped and the input AC coupled,
the minimum input frequency is 20 Hz (at specified
sensitivity).
OPERATING INSTRUCTIONS Page: 9
PM 6669 - OPERATORS MANUAL

CONTROL OPERATING THE
CONTROL DISPLAY GPIB-CODE
Move function cursor to
FREQ B FREQ B
Move function cursor to
FREQ A/A0Not bus selectable
Move function cursor to
FREQ A-A0Not bus selectable
Move function cursor to
RPM A RPM A
Move function cursor to
PER A PER A
Move function cursor to
TOT A TOTM A
FUNCTION
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
0.
FUNCTION
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
0.
FUNCTION
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
0.
FUNCTION
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
0.
FUNCTION
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
ms
0.
FUNCTION
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
0.
Page: 10 OPERATING INSTRUCTIONS
PM 6669 - OPERATORS MANUAL

FUNCTION AND RANGE HINTS AND COMMENTS
Reciprocal frequency measurement of the signal at In-
put-B.
Range:
70 to 1300 MHz (PM 9608B)
The cursor does not stop at FREQ B if no Input-B HF-
input is installed.
The counter divides the frequency on Input-A by a
constant, A0, that is stored in the counter in the follow-
ing way:
1) Connect a signal with the frequency to be stored
as A0to Input-A.
2) Select FREQ A.
3) Depress the DISPL HOLD key and hold it de-
pressed until the DISPL HOLD indicator is switched
off again. Now A0is stored.
4) Select FREQ A/A0.
5) Connect the frequency to be measured to Input-A.
If you select this function without storing A0,
Frequency A will be displayed.
This function is convenient when an oscillator is to be
tuned to the frequency of a reference oscillator. It is
much easier to adjust until the display shows
1.0000000 than 7.1223678.
The counter substracts a constant, A0, from the fre-
quency at Input-A. You can read about how to store
A0in the description for FREQ A/A0.
If you select this function without storing A0,
Frequency A will be displayed.
This function can e.g. be used in a radio to display
the received frequency; Set the intermediate
frequency as the constant A0. Select FREQ A-A0and
measure the frequency of the local oscillator, and the
display will show the received frequency.
The frequency on Input-A is multiplied by 60 and dis-
played as Revolutions Per Minute.
Range: 6 RPM to 720 000 000 RPM.
When you select SINGLE, the Frequency Counter
measures one period, the range is: 100 ns to 200
000 000 s (about 6 years and four months!).
When you select 0.2, 1, and 10 s Measuring-time, the
Frequency Counter divides the input frequency by 10
and measures the average period for the No. of cy-
cles in that time.
Range:
8 ns to 1 s.
Use SINGLE when the input frequency is low. This
shortens the measuring time considerably since one
cycle is measured instead of 10.
The Frequency Counter counts the total number of
pulses fed to Input-A. You start and stop the totalizing
with the TOTALIZE START/STOP key (RESET/LO-
CAL). If you keep this key depressed for more than
one second, the total sum will be reset.
Range:
0 to 1*1015 pulses
k on the display indicates kilo-pulses (1000) and Min-
dicates Mega-pulses(1 000 000).
The Measuring-time indicator is switched off in TOT
A MAN.
OPERATING INSTRUCTIONS Page: 11
PM 6669 - OPERATORS MANUAL

CONTROL OPERATING THE
CONTROL DISPLAY GPIB-CODE
Move function cursor to
WIDTH A WIDTH A or PWIDTH A
MEAS TIME is operated
in the same way as the
func-tions control, see
page 8.
MTIME <num>
where <num>
is the time in
seconds.
Range:
10 ms to 10 s.
0 = Single
Move the measuring-
time cursor to SINGLE MTIME 0
Move the measuring-
time cursor to 0.2 s MTIME 0.2
Move the measuring-
time cursor to 1 s MTIME 1
Move the measuring -
time cursor to 10 s MTIME 10
FUNCTION
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
ms
0.
TIME
MEAS
TIME
MEAS
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
TIME
MEAS
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
TIME
MEAS
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
TIME
MEAS
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
Page: 12 OPERATING INSTRUCTIONS
PM 6669 - OPERATORS MANUAL

FUNCTION AND RANGE HINTS AND COMMENTS
The counter measures the positive pulse width of the
signal on Input-A.
Range:
100 ns to 200 000 000 s.
If you are interested in the negative pulse width
instead; first measure the period and make a note of
the result, then measure the pulse width and
substract it from the period reading.
The set Measuring-time controls the time during
which the main gate is opened, allowing pulses to en-
ter the counting logic. A longer Measuring-time gives
higher resolution readouts with more digits displayed.
The time the gate is open is not exactly the preset
Measuring-time, because the Frequency Counter syn-
chronizes the measurement with the input signal in or-
der to measure complete periods. If the period of the
input signal is longer than the set Measuring-time, the
main gate does not close again until the period is
completed.
If you wish to do one measurement instead of
repetitive measurements, see DISPL HOLD.
For PER A and WIDTH exactly one period or one
time interval is measured. The minimum result possi-
ble is 100 ns.
The display time will be 100 ms.
When set to SINGLE, FREQ A and, RPM A, the
Measuring-time is one cycle of the input signal or
3 ms, whichever is longest. When set to SINGLE and
FREQ B, the Measuring-time is 3 ms.
The input frequency is limited to 16 MHz for FREQ A,
PER A, and RPM A.
If external reference is used, the EXT REF indicator
will not be switched-on until after the first
measurement.
A Frequency-A measurement will result in 6-7 digits
on the display.
A Frequency-A measurement will result in 7-8 digits
on the display.
A Frequency-A measurement will result in 8-9 digits
on the display.
OPERATING INSTRUCTIONS Page: 13
PM 6669 - OPERATORS MANUAL

CONTROL OPERATING THE
CONTROL DISPLAY GPIB-CODE
The TRIGGER
LEVEL A control is
operated in the same
way as the functions
control, see page 8.
One code for
each trigger
level offset.
See below.
Move Trigger Level A
cursor to AUTO.TLO AUT
Move Trigger Level A
cursor to TLO POS
Move Trigger Level A
cursor to TLO SYM
Move Trigger Level A
cursor to TLO NEG
Each depression of the
BLANK DIGITS key
blanks out one digit
starting from the right
(Least Sig-nificant Digit).
When all digits are
blanked out, the next
depression removes the
blanking.
Not bus
controllable
LEVEL A
TRIGGER
LEVEL A
TRIGGER
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
0.
LEVEL A
TRIGGER
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
0.
LEVEL A
TRIGGER
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
0.
LEVEL A
TRIGGER
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
0.
DIGITS
BLANK
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
Page: 14 OPERATING INSTRUCTIONS
PM 6669 - OPERATORS MANUAL

FUNCTION AND RANGE HINTS AND COMMENTS
The normal trigger level of the AC-coupled Input-A is
0 V. This is ideal for symmetrical signals like sine-
waves, since their average DC component is 50 % of
Vp-p.
Non-symmetrical signals however, might fail to trigger
if the trigger level is 0 V. Therefore there are three
trigger level settings available; one for small duty fac-
tors, one for symmetrical wave forms and one for
large duty factors.
It is often possible for the counter to trigger on
unsymmetrical signals even though the symmetrical
triggering is selected, provided that the sensitivity is
high enough. This however, gives poor noise
immunity.
If you don’t know the duty factor of the input signal,
select Auto. If that does not work (too low input
frequency) do as follows;
a) Set the sensitivity to max.
b) Select Trigger level .
c) Reduce the sensitivity until the gate indicator stops
blinking.
d) Check if trigger level or makes the gate
indicator start blinking again. If it does, leave the
trigger level in that position, otherwise return to trigger
level .
e) Turn the sensitivity down until the gate indicator
stops
blinking, then up slightly until it starts again. The
trigger
level is now correct.
When set to Auto the counter first tries the trigger
level for symmetrical signals. If that does not work, it
tries the other settings.
Auto does not work if TOT A is selected.
Range: Auto works with input frequencies from 100
Hz and up.
Use this setting if the duty factor is below 25 %.
A positive offset voltage is added to the trigger level.
Use this setting if the duty factor is between 25 %
and 75 %.
The trigger level is 0 V.
Use this setting if the duty factor is below 75 %.
A negative offset voltage is added to the trigger level.
Each digit that is blanked out is removed and re-
placed by a -. The numerical value on the display is
not rounded off. The blanking is cleared by reset,
changing settings or when all digits are blanked and
you press the BLANK DIGITS key once more.
This function is used to blank the display of irritating,
unstable digits.
OPERATING INSTRUCTIONS Page: 15
PM 6669 - OPERATORS MANUAL

CONTROL OPERATING THE
CONTROL DISPLAY GPIB-CODE
RESET/LOCAL, a short
press is enough for
Reset. When the remote
indicator is on, a press
will cause the counter to
switch back to LOCAL,
i.e. control from the front
panel.
TOTALIZE
START/STOP, one
press starts totalizing,
the next press stops.
Xstarts a new
measurement.
GATE OPEN
starts and
GATE CLOSE
stops Totalize
MAN.
Switches ’on’ or ’off’
DISPL HOLD when de-
pressed.
Not bus con-
trollable, but
Free-run OFF
will give a
similar function;
See GPIB-bus
operation.
Connect the signal to
INPUT-A via a BNC-
cable.
Connect the signal to
INPUT-B via a BNC-
cable.
LOCAL
RESET
START/STOP
TOTALIZE A
HOLD
DISPL
A
0
STORE
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
ums
GATE
0.
M
10Hz-160MHz
MAX 350Vp
1M
Ω
30pF
INPUT A
OPTION
70MHz - 1.3GHz
MAX 12Vrms
50 Ω
INPUT B
Page: 16 OPERATING INSTRUCTIONS
PM 6669 - OPERATORS MANUAL

FUNCTION AND RANGE HINTS AND COMMENTS
When reset is depressed, the display and counting
registers are cleared. When reset is released, a new
measurement is started. The Measuring-time-, Func-
tionand display hold- settings are not affected.
If the TOT A function is selected, the RESET/LOCAL
key functions as a START/STOP key. One press
starts the counting and the next press stops it. A long
depression results in reset.
When the counter is controlled from the GPIB-Bus,
the LOCAL key can be disabled via the ’Local Lock
out’ command.
Display hold freezes the display, but not until the
measurement in process has been finished. A new
measurement can always be initiated via the RESET
key.
Store A0is used to store the constant used in func-
tions FREQ A/A0and FREQ A-A0. The procedure is
described under FUNCTIONS, FREQ A/A0.
Use this input for all functions except FREQ B.
Range: 10 Hz to 160 MHz
Impedance: 1 M //30 pF
Min. pulse duration:4 ns
At higher frequencies; use a 50 Ωtermination type
PM 9585 to avoid interference caused by impedance
mis match.
The illustration below shows which function block
each of the input controls affect.
This is the HF-input which must be used when the
FREQ-B function is selected. If the Frequency
Counter does not include the Input-B option, the BNC-
connector is replaced by a plastic plug.
Range:
70 to 1300 MHz.
Impedance:
50Ω
Sensitivity:
10 mVRMS up to 900 MHz,
15 mVRMS
900-1100 MHz
and 40 mVRMS above.
Max voltage:
12 VRMS
8 V
0 440 Hz 1 MHz 120 MHz
20Hz
20 mV
40 mV
60 mV
030 MHz 120 MHz 160 MHz
AC Spec.
DC Spec.
Typically
RMS
Max voltage
350 V
DC+ACpeak
Sensitivity
Attenuator
Sensitivity range switch
Counting
logic
Trigger level offset
Input-A
Filter
Sensitivity
control
Figure 7. Input circuit block diagram.
OPERATING INSTRUCTIONS Page: 17
PM 6669 - OPERATORS MANUAL

CONTROL OPERATING THE
CONTROL DISPLAY GPIB-CODE
Pull the SENSITIVITY
knob to switch to AC
coupling. Depress the
knob to switch to DC
coupling.
NOTE: The
potentiometer controls
the sensitivity when AC-
coupled and Trigger
Level when DC-coupled.
Turn the knob clockwise
to increase and counter
clockwise to decrease
the trigger level or
sensitivity.
Not adjustable
from the bus.
One two-position switch.
Depress to switch on
the FILTER and relase
to switch it off.
Not bus
controllable.
Connect an external
10 MHz frequency
source to the BNC-
connector on the rear
panel of the Frequency
Counter marked EXT
REF INPUT.
Not bus
controllable.
200mVrms
10mVrms
MIN
SENSITIVITY
INPUT A
INPUT A
FILTER<50kHz
1
0MHz 0.5-15Vrm
s
EXT REF INPUT
TRIGGER LEVEL A
HOLD
DISPLMEASURING TIME 10s1s0.2sSINGLE
REF
EXT
A
WIDTH
A
TOT
A
PER
A
RPM
A-A
0
FREQ
A/A
0
FREQ
B
FREQ
A
FREQ
FUNCTION
AUTO
kHz
u ms
GATE
0.
M
Page: 18 OPERATING INSTRUCTIONS
PM 6669 - OPERATORS MANUAL

FUNCTION AND RANGE HINTS AND COMMENTS
For frequency-, period-, and ratio measurements:
Select AC coupling and set the sensitivity so that the
hysteresis band of the Frequency Counter is about
half the amplitude of the signal.
For time measurements:
Select DC coupling and set the trigger level to the de-
sired level using the 1 V/divistion scale on the front
panel.
1. Set the sensitivity knob fully counter clockwise.
2. Turn it until the input triggers.
3. Continue turning to the 20 mVRMS position, or to the
position where the display turns unstable due to noise.
4. Set the knob to the position inbetween these two
points.
You will have a stable reading.
If the sensitivity is too high, the Frequency Counter
will be triggered by noise and interference instead of
by the signal.
The filter works on Input-A where it suppresses sig-
nals with higher frequencies than 50 kHz.
Filter suppression: 40 dB at 1 MHz
The filter can also be used to suppress HF-
interference on signals with higher frequencies than
50 kHz, but then the sensitivity of the input will be
reduced.
NOTE: Never use the filter when measuring TIME A-B
since the filter delays the signal on Input-A.
The Frequency Counter automatically detects if a suit-
able signal is connected to the EXT- REF Input-con-
nector.
Suitable signal:
10 ±0.1 MHz, 0.5 to 15 VRMS Sine wave.
Use external reference when the measurement
requires ultra-high stability.
The Frequency Counter must still have the internal
time base even if an external reference frequency is
used.
If single is selected, the EXT REF indicator on the
display is not switched on until after the first
measurement.
OPERATING INSTRUCTIONS Page: 19
PM 6669 - OPERATORS MANUAL