Equipment information:

Marconi 2300A Level Meter
Manufacturer:
Marconi
Model: 2300A
Date: 1974
Category: Measurement instruments
Group: Level Meter
Description: F.M./A.M. Modulation Meter
Information:
                                    The TF 2300A Modulation Meter is primarily for measurement
of f. m. deviation but it also measures a. m. depth. With
its wide range of deviation frequency, modulation bandwidth
and carrier frequency, this instrument is suitable for
application to fixed and mobile point-to-point
communications, broadcasting, telemetry and multi-channel
link equipment in the h. f. , v. h. f. and u. h. f. bands.
Distortion and channel separation tests on f. m. stereo
receivers and transmitters can also be made.
Positive and negative f. m. deviation can be measured in
ranges from 1. 5 kHz to 500 kHz full- scale at modulation
frequencies between 30 Hz and
3.4 kHz on the 1. 5 kHz deviation range, and 30 Hz and 200
kHz on all other deviation ranges. A. M. depth can be
measured up to 95% in a 30 Hz to 15 kHz modulation
bandwidth. Either f. m. or
a. m. can be measured in the presence of the other. Although
measurements are normally made by means of the meter
readout, i. f. and demodulated outputs are available at the
front panel for examination or analysis.
Spurious a.m. and f. m. due to hum and noise are kept to a
level insignificant for most applications but, where
required, crystals can be switched in to control the local
oscillator, or an external local oscillator may be used. The
instrument can be operated without a local oscillator for
measurements in the 1-2 MHz range.
The instrument can be operated from mains power or a nominal
24 V battery. Voltage regulation eliminates transformer tap
changing except between 115 V and 230 V ranges. On battery,
the regulation compensates for battery voltage variations
between 21.5 and 30 V. Transistorized circuits consuming
little current give reasonable length of operation
onbatteryfor mobile purposes.

These manuals are available for the above equipment:

Marconi -- 2300A -- Service and User Manual
File name: Marconi-7768-Manual-Page-1-Picture
Manual Type: Service and User Manual
Pages: 90
Size: 28.39 Mbytes (29773693 Bytes)
Language: english
Revision:
Manual-ID/Number:
Date: January 1974
Quality: Scanned document, all readable.
Upload date:
MD5: 64c4df8f29ba8c0783c66a9183d4b256
ed2kID: 173ce1ae05caa65c4631f59077958be6
Downloads: 100 since 20 February 2016
Information:
Section 1 GENERAL INFORMATION
1.1 Introduction ... ... ... ... 5
1.2 Data summary ... ... ... ... 6
1.3 Accessories ... ... ... ... 10
Section 2 OPERATION
2.1 Installation ... ... ... ... 11
2.2 Power supply ... ... ... ... 11
2.3 Controls ... ... ... ... 12
2.4 Preparation for use . . ... ... ... 14
2.5 Measuring f. m. deviation ... ... ... 14
2.6 Measuring a, m. depth ... ... ... 15
2.7 Measuring f. m. on a.m. ... ... ... 15
2.8 Measuring a. m. on f. m. ... ... ... 16
2.9 Noise measurements . ... ... ... 16
2.10 Oscillator arrangements ... ... ... 18
2.11 Measurement in 1 to 2 MHz range ... ... 19
2.12 Asymmetric modulation and carrier shift ... ... 19
2.13 Use of 1. f. output terminals ... ... ... 20
2.14 Use of i. f. output socket ... ... ... 20
2.15 Crystal selection ... ... ... ... 20
2.16 F. M. stereo measurements ... ... ... 21
2.17 Phase modulation and telemetry deviation ... ... 24
2.18 Stray fields ... ... ... ... 24
Decibel conversion tables ... ... ... 25
Section 3 TECHNICAL DESCRIPTION
3.1 System operation ... ... ... ... 27
3.2 Power unit ... ... ... ... 28
3.3 Mixer ... ... ... ... 29
3.4 Local oscillator ... ... ... ... 29
3.5 I. F. amplifier ... ... ... ... 30
3.6 Limiter ... ... ... ... 30
3.7 Discriminator ... ... ... ... 30
3.8 Calibrator ... ... ... ... 30
3.9 Low-pass filters ... ... ... ... 31
3.10 1st 1. f. amplifier ... ... v.;. :"r - .... 31
Section 3 Continued
3.11 2nd 1, f. amplifier ... ... ... ... 31
3.12 Peak reading meter .. ... ______________... 32
3.13 A.M. detector ... ... ... ... 32
3.14 Between-units circuitry on chassis ... ... 32
Section 4 MAINTENANCE
4.1 Introduction ... ... ... — 33
4.2 Access and layout .... ... ... ... 33
4.3 Performance checks ... ... ... 33
Component layout illustrations.. ... ... 34
4.4 Cleaning and lubricating ... ... ... 40
Section 5 REPAIR
5.1 Introduction ... ... ... ... 42
5.2 Fault location ... ... ... ... 42
5.3 Waveforms ... ... ... ... 43
5.4 Realignment ... ... ... ... 43
5.5 Replacement of sub-assemblies . ... ... 49
5.6 Replacement of components ... ... ... 50
Section 6 REPLACEABLE PARTS
Introduction ... ... . ·. ... 65
Section 7 CIRCUIT DIAGRAMS
Circuit notes ... ... ... ... 78
Fig. 7.1 Inter-unit wiring ... ... ... ... 79
Fig. 7.2 Mixer, oscillator and i. f. amplifier ... ... 81
Fig. 7. 3 Limiter, discriminator and 1st 1. f. amplifier — 83
Fig. 7. 4 2nd 1. f. amplifier and voltmeter ... ... 85
Fig. 7.5 A. M. detector and calibrator... ... ... 87
Fig. 7.6 Power supply unit .. ... ... ... 89
Marconi-7768-Manual-Page-1-Picture
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