Marconi - TF 2300B - Level Meter
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Equipment:
TF 2300B
Date:
1983
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Information
The TF 230OB Modulation Meter measures f.m. deviation and
a.m. depth. With its wide range of deviation frequency,
modulation bandwidth and carrier frequency, the instrument
is suitable for application to fixed and mobile
point-to-point communications, broadcasting, telemetry and
multi-channel link equipment in the h.f.s v.h.f. and u.h.f.
bands. Distortion and channel separation tests on f.m.
stereo 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. AM depth can be measured
up to 95% in a 30 Hz to 50 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, an optional crystal Oscillator can be fitted, or
an external local Oscillator may be used. The instrument can
be operated without a local Oscillator for measurements in
the 1 to
2 MHz range.
1 Manual
Service and user manual
Manual type:
Service and user manual
Pages:
78
Size:
3.3 MB
Language:
english
Revision:
Manual-ID:
46881-280J
Date:
Quality:
Scanned document, all readable.
Upload date:
May 28, 2016
MD5:
18396fbc-4e5b-340f-2225-a36555781b39
Downloads:
691
Information
Chapter 1 GENERAL INFORMATION
1.1 introduction ... ... ... ... ... ... ... ... 5
1.2 Data summary — ... ... ... ... ... — ... 6
1.3 Accessories __ ... — ... ... ... ... ... 9
Chapter 2 OPERATION
2.1 Installation ... ... ... ... ... ... ... ... 12
2.2 Power Supply 12
2.3 Controls and connectors ... ... ... ... ... ... 12
2.4 Preparation for use ... ... ... ... ... ... ... 14
2.5 Measuring f.m. deviation ... ... ... ... ... ... 14
2.6 Measuring a.m. depth ... ... ... ... ... ... 14
2.7 Measuring f.m. on a.m. ... ... ... ... ... ... 15
2.8 Measuring a.m. on f.m. ... ... ... ... ... — 15
2.9 Noise measurements ... ... ... ... ... ... ... 16
2.10 Oscillator arrangements and operating notes ... ... ... 18
2.10.1 Internal Oscillator — ... ... ... ... ... 18
2.10.2 External Oscillator 18
2.10.3 Use above 1200 MHz
...18
2.11 Use of crystal Oscillator TK 2302
...18
2.11.1 Fitting the crystal Oscillator 18
2.11.2 Crystal selection ... ... ... ... ... ... 19
2.11.3 Crystal Oscillator operation ... ... ... ... 20
2.12 Measurement in 1 to 2 MHz range ... ... ... ... ... 20
2.13 Asymmetric modulation and carrier shift ... ... ... ... 20
2.14 Use of 1.f. output socket
...20
2.15 Use of i. f. output socket ... ... ... ... ... ... 20
2.16 FM stereo measurements ... ... ... ... ... ... 21
2.16.1 Harmonic distortion — ... ... ... ... ... 21
2.16.2 Channel separation ... ... ... ... ... ... 22
2.17 Phase modulation ... ... ... ... ... ... ... 23
2.18 Telemetry deviation ... ... ... ... ... · ·. ... 23
Decibel conversion table ... ... ... ... ... ... 24
Chapter 3 TECHNICAL DESCRIPTION
3.1
Introduction ... ... ... ... ... ...
... 26
3.2
Circuit summary ... ... ... ... ...
... 26
3.3
Mixer - unit A1 ... — ... ...
... 27
3.4
Local Oscillator units A2, A2a and A2b ...
... 27
3.5
IF Amplifier unit A3 ... ... ...
... 28
3.6
Limiter - unit A4 ... ... ... ...
... 28
3.7
Discriminator - unit A5 ... ... ... ...
... 28
3.8
200 kHz low-pass Filter unit A6 — ...
29
3.9
1st 1. f Amplifier unit A7 ... ... ... ...
... 29
3.10
15 kHz low-pass Filter unit A8 ... ... ...
... 29
3.11
2nd l.f Amplifier unit A9 ... ... ... ...
... 29
3.12 Peak reading voltmeter - unit A10 ... ______... ... ... 30
3.13 AM detector - unit All __ ... ... ... .. ^ ... 30
3.14 Calibrator unit A12 ... ... ... ... — ... ... 30
3.15 Power Supply unit A13 ... ... ... ... ... 30
3.16 Crystal Oscillator TK 2302
...
31
Chapter 4 MAINTENANCE
4.1 Introduction ... ... ... ... ... ... ... ... 33
4.2 Access and layout — ... ... ... ... — ... 33
4.3 Performance checks ...
... ... ... 33
4.3.1 Test equipment required ... ... ... ... ... 33
4.3.2 RF input and i.f. output ... ... ... ... ... 33
4.3.3 PM deviation accuracy ...
... ... 37
4.3.4 AM depth accuracy ... __ ... ... ... ... 38
4.3.5 FM noise
...
39
4.3.6 FM distortion ...
... ... ... 39
4.3.7 AM rejection ... ... ... ... ... ... ... 40
4.4 Cleaning and lübricating ... ... ... ... ... ... 41
Chapters REPAIR
5.1 Introduction ... ... ... ... ... ... ... ... 42
5.2 Fault location ... ... ...
... ... ... 42
5.2.1 Test equipment required ... ... ... ... ... 42
5.2.2 Front panel checks ... ...
... ... 42
5.2.3 Noise ·■· ...
... ... ... 43
5.2.4 Internal checks ... ...
... ... 43
5.3 Waveforms ... ...
... ... ... 43
5.4 Realignment ... ...
... ... ... 45
5.4.1 Introduction ... ... ... ... ... ... ... 45
5.4.2 Test equipment required ... ... ... ... ... 45
5.4.3 Power Supply (A13) ... ...
... ... 45
5.4.4 Local Oscillator (A2, A2a and A2b) ... ... ... ... 46
5.4.5 Minimum sensitivity ... ... ... ... ... ... 47
5.4.6 De-emphasis ... ... ... ... ... ... ... 48
5.4.7 Range attenuator ... ... ... ... ... ... 48
5.4.8 AM and i.f. response ...
... ... 49
5.4.9 Discriminator trigger ... ... ... ... ... 49
5.4.10 IF Amplifier A3 ... ... ... ... ... ... 49
5.4.11 LF and discriminator noise
... ... ... 50
5.5 Replacement of sub-assemblies ... ... ... ... ... 50
5.6 Oscillator drive cord ... ... ... ...
... ... 51
5.7 Replacement of components ... ... ... ... ... ... 51
Chapter 6 REPLACEABLE PARTS
Introduction and ordering ... ...
... ... 52
Chapter 7 CIRCUIT DIAGRAMS
Circuit notes ... ... ... ... ... ... ... 64
Fig. 7.1 Inter-unit wiring ...
... ... ... 65
Fig. 7.2 Mixer Oscillator and i.f Amplifier 67
Fig. 7.3 Limiter, discriminator and 1st I.f Amplifier 69
Fig. 7.4 2nd I.f Amplifier and peak reading voltmeter ...
... ... 71
Fig. 7.5 AM detector and Calibrator 73
Fig. 7.6 Power Supply unit ... ... — ... ... ... ... 75