Marconi - 2955R - Communications Test Set
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Equipment:
2955R
Date:
1989
Category:
Group:
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Information
Radio Communications Test Set 2955A provides comprehensive
test facilities for AM, FM and ΦΜ mobile radio transceivers
operating up to 1000 MHz.
The 2955A is a combination of the following instruments:-
RF power meter.
DC and AF voltmeter.
RF counter.
AF counter.
RF generator.
AF generators (two).
Modulation meter.
AF distortion meter.
S/N and SINAD meter.
Sequential tones decoder and encoder.
DTMF decoder and encoder.
DCS decoder and encoder.
POCSAG radio pager encoder.
Digital oscilloscope.
These are automatically connected to the appropriate socket
w'hen an operating mode is selected.
A large CRT display shows all the generated and measured
information for each test and a direct indication of the
control settings being used.
The 2955A can be used to check a wide range of equipment
including simplex and duplex radio telephones and mobiles
using selective calling and cross-band repeaters.
Push-button selection makes all the necessary interconnections for each
measurement, eliminating the need for the many interconnections required
when separate instruments are used. Function selection and data entries are
made on a colour-coded keyboard with the operating sequence logically
arranged from left to right. Instrument operation is greatly facilitated by
means of CRT displays which provide prompts during data entry and
guidance during operating sequences while also showing the instrument
settings and the measurement results. The measurement results are
displayed by digital readouts and also by either autoranging bar charts or by
a storage oscilloscope which has repetitive sweep, single shot and freeze
facilities.
Radio Communications Test Set type 2955R is identical to the 2955A except
that the 2955R also contains a sensitive receiver for off-air monitor testing of
transmitters.
Frequency meters. As there are two frequency counters, simultaneous AF
and RF frequency readings can be displayed. Ranges and resolutions are
respectively from 20 Hz to 20 kHz at 0.1 or 1 Hz and from 1.5 to 1000 MHz at
1 or 10 Hz. Either an internal or an external frequency standard can be used.
Signal generator. The signal generator can be amplitude, frequency, or phase
modulated, internally or externally, the internal modulating signal being
obtained from the AF generators. Amplitude modulation is variable up to 99%
for carrier frequencies from 0.4 to 500 MHz. FM deviation can be set from 0
to 25 kHz and <£M deviation from 0 to 10 radians. Transmitter and receiver
RF signals use N and BNC connectors which are selected by means of a key.
Reverse power overload is indicated by a visual warning and an audible
alarm. When a reverse power overload is applied to the BNC socket, an
automatic trip circuit operates.
Modulation meter. Automatic frequency tuning and levelling of the
modulation monitor provide accurate measurements of AM, FM and <i>M.
Because of the independent tuning, modulation measurements can be made
on duplex systems. The modulation can be observed on an oscilloscope and
its symmetry checked from the peak and trough values displayed on a dual
bar chart. The demodulated output is available at a rear panel socket.
Provision is made for audible monitoring using the built-in loudspeaker or by
an external loudspeaker or headphones.
RF power meter. The absorption RF power meter measures up to 75 W
continuously or up to 150 W for short periods over a frequency range of 1.5
to. 1000 MHz. The connection of the RF Directional Power Head (available as
an optional" accessory) extends the capability of the instrument by enabling
measurements of ¡forward power, reverse power and VSWR to be made.
AF generators. The two AF generators provide a range of frequencies from 20
Hz to 20 kHz for single-tone or two-tone testing. The audio output is available
at a front panel socket and the generators also provide the internal AM, FM
and <I>M for the RF signal generator. A combined 600 £2 Balanced to
Unbalanced Convertor and 20 dB Attenuator is available as an optional
accessory.
AF voltmeter. Operating in the range 20 Hz to 20 kHz, the true RMS voltmeter
has provisions for measuring AF or AF plus the DC component. Band-pass
and low-pass filters can be selected. :
Distortion, S/N (signal to noise) or SINAD (signal to noise and distortion)
meter.
The AF distortion and noise meter operates at 1 kHz which is supplied by one
of the AF generators. The bar chart displays are autoranged at 10% and 30%
(for distortion), at 30 and 100 dB (for S/N) or at 18 and 50 dB (for SINAD). The
Psophometric Filter Units (available as optional accessories) enable CCITT
and C-message weighted measurements to be made.
Sequential tones decoder and encoder. For testing selective calling tones
encoding and decoding equipment, the instrument is capable of receiving and
generating five defined tone frequency standards plus a user-defined
standard. Provision is made to receive and to send sequences of up to 33
tone frequencies. For transmitter testihg, each received tone is compared
with the standard frequency allocations which is held in memory and, if it is
within the limits, its tone number and % frequency error are displayed. For
receiver testing, the tones can be generated in single step, tone burst or
continuous cycle. There is a revertive tones facility whereby tones are sent to
a receiver and the the answering sequence is decoded.
DTMF decoder and encoder. There are similar facilities for testing DTMF
encoding and decoding equipment.
DCS decoder and encoder. There are similar facilities for DCS encoding and
decoding equipment.
POCSAG radio pager encoder. The instrument can be used to check the
response of a pager to an RF signal modulated with the pager’s address and
an appropriate message. Deliberate errors can be created in the outgoing
signal.
GPIB interface unit. This unit allows the instrument to form part of an
automatic test system. The GPIB additionally enables a display to be
configured to the user’s own requirements using a comprehensive character
set. The GPIB also enables the 24 Column Printer (available as an optional
accessory) to be used.
3 Manuals
Service manual
Manual type:
Service manual
Pages:
433
Size:
15.3 MB
Language:
english
Revision:
Issue 4
Manual-ID:
46881-954A
Date:
Quality:
Scanned document, reading partly badly, partly not readable.
Upload date:
May 29, 2016
MD5:
deb0f3ab-8da2-d887-39e5-9a7e066d84a2
Downloads:
1909
User manual
Manual type:
User manual
Pages:
174
Size:
4.7 MB
Language:
english
Revision:
5
Manual-ID:
46881-952B
Date:
January 1989
Quality:
Scanned document, reading partly badly, partly not readable.
Upload date:
Jan. 5, 2019
MD5:
a29951d1-a08a-7650-e397-f5fd027be877
Downloads:
538
Service manual
Manual type:
Service manual
Pages:
48
Size:
2.2 MB
Language:
english
Revision:
revised
Manual-ID:
Date:
December 2001
Quality:
Scanned document, all readable.
Upload date:
Jan. 6, 2019
MD5:
df723a60-cfca-ae9a-5cfa-3613f07cf9a7
Downloads:
633