Thurlby Thandar Instruments PFM3000 User Manual [en, de, fr, it]

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THURLBY THANDAR INSTRUMENTS

PFM3000

PORTABLE FREQUENCY METE

INSTRUCTION MANUAL

Table of Contents

Introduction 1
Specification 2
Safety 4
EMC 4
Operation 6
Calibration and Maintenance 7

Instructions en Francais

Securite 8
Fonctionnement 9
Calibration et Entretien 10

Bedienungsanleitung auf Deutsch

Sicherheit 11
Betrieb 12
Eichung und Wartung 13

Istruzioni in Italiano

Sicurezza 14
Funzionamento 15
Taratura e Manutenzione 16

Instrucciones en Español

Seguridad 17
Functionamiento 18
Calibración y Mantenimiento 19

Introduction

The PFM3000 is a portable frequency meter with a large 11.5mm 8½-digit liquid crystal display
(LCD). The frequency range is 3Hz to 3GHz and measurement capabilities include frequency and
period with push-to-measure and auto power-down functions.

A hold function is available which allows any reading to be frozen and displayed indefinitely.
Input A is a high impedance input (1M) for frequencies in the range 3Hz to 125MHz. Input B is a

nominal 50 input for frequencies in the range 80MHz to 3GHz.
The instrument uses a reciprocal counting technique to provide high resolution at all frequencies.

At least 7 significant digits of answer are produced per second of measurement time.
A low pass filter can be selected to ensure stable readings at low frequencies.
Indicators show measurement function, measurement time, low battery and the units of the answer

which may be Hz, kHz, MHz, ns, us, ms or s.
The low power design gives typically 20 hours battery life from a 9 volt alkaline cell. Use of the

power saving push-to-measure functions will avoid wasting battery life by automatically switching
the unit off after a short time.

The instrument has a robust ABS case.

1

MEASUREMENT FUNCTIONS

Frequency (Range A)

Frequency Range: 3Hz to >125MHz
Resolution: 10

Frequency (Range B)

Frequency Range: 80MHz to >3000MHz
Resolution: 1Hz to 10kHz (see below)

Period (Range A only)

Period Range: 8ns to 330ms
Resolution: 10

Measurement time

Selectable as 10s, 1s or 0.3s.

-7

Hz to 100Hz (see below)

-7

ns to 1us (see below)

Specification

Resolution

The displayed resolution depends upon the measurement time and the input frequency. Eight or
nine digits are displayed for a 10 second measurement time. Six, seven or eight digits are displayed
for the shorter measurement times depending on input frequency. Usable resolution can be further
reduced by noise, especially at low frequencies.

Accuracy

Measurement accuracy is the sum of timebase accuracy and measurement resolution plus one
count.

TIMEBASE

Crystal Oscillator Frequency:

Initial Oscillator Adjustment Error: ± 2ppm (closed-case adjustment by user)
Oscillator Temperature Coefficient: Typically less than

Oscillator Ageing Rate: <± 5ppm/year

OPERATING FUNCTIONS

Press to measure

With the power switch off, pressing any of the function select keys will power the instrument up in
the corresponding function. The instrument will automatically switch off 15 seconds after the last
key-press.

10MHz

± 0.3ppm/°C 18°C to 28°C,
± 10ppm –20°C to 70°C

Hold

Pressing the Hold key will stop further measurements being made and the current measured value
will remain in the display, with the Hold indicator on, until the Hold key is pressed again.

Noise filter

The Filter key controls a low pass filter, with a cut-off frequency of about 50kHz, to ensure stable
readings at low frequencies.

Signal activity indicator

When no input signal is detected the Trig indicator will be off, indicating that no measurement is
possible. The gate time indicator flashes until the first measurement interval is complete.

2

INPUT SPECIFICATIONS

Input A

Input Impedance:
Frequency Range: <3Hz to >125MHz
Sensitivity: Sinewave - 15mVrms 10Hz to 125MHz

Input B

Input Impedance:
Frequency Range: <80MHz to >3GHz
Sensitivity: Sinewave - 12mVrms 80MHz to 2GHz, 25mVrms to 2.5GHz,

Maximum Input Voltage

Input A and Input B:

Note that the inputs will not be damaged if subjected to an accidental short-term connection to a
50/60Hz line voltage not exceeding 250V rms.

POWER REQUIREMENTS

1MΩ//20pF (AC coupled)

50Ω nominal (AC coupled)

50mVrms to 3GHz

30Vdc; 30V rms 50/60Hz with respect to ground
to 1Vrms above 1MHz

, reducing

Battery Type: 9V PP3 alkaline
Battery Life: Typically 20 hours
Low Battery Indicator: ‘Bat' shows in display when approximately 10% of battery life

GENERAL

Display: 8½ digit LCD,

Operating Range: +5°C to +40°C, 20% to 80% RH
Storage Range:
Environmental: Indoor use at altitudes up to 2000m Pollution Degree 2
Size: 81mm x 178mm x 30mm (WxLxD)
Weight: 190gms excluding battery
Electrical Safety: Complies with EN61010-1
EMC: Complies with EN61326

remains.

11.5mm high (0.45”);
15 annunciators show measurement units, input, mode and
time.

–20°C to +60°C

3

Safety

This instrument is Safety Class III according to IEC classification and has been designed to meet
the requirements of EN61010-1 (Safety Requirements for Electrical Equipment for Measurement,
Control and Laboratory Use). This instrument has been tested in accordance with EN61010-1 and
has been supplied in a safe condition. This instruction manual contains some information and
warnings which have to be followed by the user to ensure safe operation and to retain the
instrument in a safe condition. This instrument has been designed for indoor use in a Pollution
Degree 2 environment in the temperature range 5°C to 40°C, 20%-80% RH (non-condensing).
It may occasionally be subjected to temperatures between +5°C and –10°C without degradation of
its safety. Do not operate while condensation is present. Use of this instrument in a manner not
specified by these instructions may impair the safety protection provided. Do not operate the
instrument outside its rated supply voltages or environmental range.

WARNING! All accessible parts will be at the same voltage potential as the outer of the BNC input
sockets: to maintain user safety it is therefore essential that neither input is connected to a voltage

above 30Vdc or 30Vrms with respect to ground
accidental connection to an AC line voltage up to 250V rms, 50/60Hz, users will be at risk if the
instrument 'ground' is connected to such hazardous voltages. The apparatus shall be disconnected
from all voltage sources before it is opened for any adjustment, replacement, maintenance or repair,
including replacement of the battery.

. Note that although the inputs will withstand

Any adjustment, maintenance and repair of the opened instrument under voltage shall be avoided
as far as possible and, if inevitable, shall be carried out only by a skilled person who is aware of the
hazard involved.

Do not wet the instrument when cleaning it. The following symbol is used on the instrument and in
this manual:

This instrument has been designed to meet the requirements of the EMC Directive 2004/108/EC.
Compliance was demonstrated by meeting the test limits of the following standards:

Emissions

EN61326 (2006) EMC product standard for Electrical Equipment for Measurement, Control and
Laboratory Use. Test limits used were: Radiated: Class B

Immunity

EN61326 (2006) EMC product standard for Electrical Equipment for Measurement, Control and
Laboratory Use.

Test methods, limits and performance achieved are shown below (requirement shown in brackets):

meaning CAUTION. Damage to the instrument may occur if these
precautions are ignored.

EMC

4

a) EN61000-4-2 (2006) Electrostatic Discharge : 4kV air, 4kV contact, Performance A (B).
b) EN61000-4-3 (2006) Electromagnetic Field:

3V/m, 80% AM at 1kHz, 80MHz - 1GHz: Performance A (A) and 1.4GHz to 2GHz:

Performance A (A); 1V/m, 2.0GHz to 2.7GHz: Performance A (A).
c) EN61000-4-4 (2004) Fast Transient, 0.5kV peak (signal inputs), Performance B (B).
According to EN61326-1 the definitions of performance criteria are:

Performance criterion A: ‘During test normal performance within the specification limits.’
Performance criterion B: ‘During test, temporary degradation, or loss of function or performance

which is self-recovering.

EC Declaration of Conformity

We Thurlby Thandar Instruments Ltd
Glebe Road
Huntingdon
Cambridgeshire PE29 7DR
England

declare that the

PFM3000 Hand-held Counter (battery operated)

meets the intent of the EMC Directive 2004/108/EC and the Low Voltage Directive 2006/95/EC.
Compliance was demonstrated by conformance to the following specifications which have been
listed in the Official Journal of the European Communities.

EMC

Emissions: EN61326-1 (2006) Radiated, Class B
Immunity: EN61326-1 (2006) Immunity Table 1, referring to:

a) EN61000-4-2 (1995) Electrostatic Discharge

b) EN61000-4-3 (2006) Electromagnetic Field

c) EN61000-4-4 (2004) Fast Transient

Performance levels achieved are detailed in the user instruction leaflet.

Safety

EN61010-1, Pollution Degree 2.

CHRIS WILDING
TECHNICAL DIRECTOR

1 May 2009

5

Power

To fit or replace the battery, undo the battery cover screw and lift off the cover. Fit the battery snap,
observing the correct polarity, insert the battery into the compartment and replace the cover.
WARNING! To prevent shock hazard, all inputs must be removed before changing the battery.
Turn the instrument on by sliding the power switch on the left-hand side of the instrument to ON.
With no signal connected the display should show 0.0, the Function annunciator (default FREQ A),
and the selected measurement time annunciator flashing (default 0.3s).

Function and Measurement Time Selection

Pushing any of the keys, FREQ A, FREQ B or PERIOD A, will set the instrument to the respective
function and the selected function will be shown by annunciators in the LCD. Select the
measurement function appropriate to the signal to be measured and connect the signal to the
corresponding BNC input; the TRIG annunciator should show in the display to indicate that the
signal has been detected. Measurement time is selected by pressing the TIME key, the selected
time being shown by the appropriate annunciator in the LCD. Switching between FREQ A and
PERIOD A will immediately convert the present measurement; otherwise a change of function or
measurement time will initiate a new measurement. This may also be accomplished without a
change of function or measurement time by pressing the key corresponding to the function currently
selected; the new measurement will start immediately.

Operation

Inputs

When a measurement is started, the measurement time annunciator flashes until a true result for
that selected measurement time is displayed, at which point the annunciator stays on. Further
display updates then show the running average of the signal behaviour over the last 0.3s (1
update), 1s (2 updates per second) or 10s (1 update per second) depending on the selected
measurement time. Note that if a 1s or 10s measurement time is selected, starting or restarting the
measurement gives a true result with at least 6 digits after 0.3s, followed by at least 7-digits after 1s
and, finally, at least 8-digits after 10s (if 10s measurement is selected).

The frequency and period measurement functions both produce at least 7 digits of answer per
second of measurement time and the units and decimal points are adjusted automatically to give the
answer in the most convenient units. Pressing the HOLD key will stop the measurement and freeze
the display with the 'Hold' annunciator showing in the LCD. Hold may be cancelled by a second
press of the HOLD key. With the power switch in the off position pressing one of the function keys
will power the instrument on and set the selected function. The instrument will then function
normally and respond to all key presses.

After a period of about 15 seconds with no key presses the instrument will automatically power
down to conserve the battery. Switching the ON/OFF switch ON then OFF during these 15 seconds
will have no effect.

Socket A is used for frequencies in the range 3Hz to 125MHz. Input impedance is 1MΩ in parallel
with 20pF. Care should be taken when measuring input signals above 350mV rms (the onset of
diode clipping) with poor signal to noise ratios as under these circumstances it is possible for noise
to generate spurious counts. To ensure a correct count, therefore, noisy signals should be
attenuated externally before being presented to the counter. A convenient attenuation factor of 10
can be achieved by the use of a x10 oscilloscope probe. The A socket will accept most types of
waveform – including sine, square and pulse signals. With pulse waveforms the mark to space ratio
should not exceed 90% and the minimum pulse width should be greater than 3ns. A low pass filter
with a cut-off frequency of 50kHz may be selected by pressing the FILTER key. The message FILT
ON shows briefly in the display and the Filt annunciator is turned on; pressing FILTER a second
time turns the filter off (display briefly shows FILT OFF and the Filt annunciator goes off). Use the
filter with low frequency large amplitude signals.

6