Marconi TF 2002B Generator
The TF 2002B
gives high quality a. m. outputs from 10 kHz to 88 MHz and f.
m. outputs between 100 kHz and 88 MHz. It has very high frequency
discrimination which, coupled with the good stability reached soon after
switching on, makes it particularly suitable for setting up and adjusting crystal
controlled receivers where the channel spacing is small and the i. f. pass
band must have an accurate absolute setting. Another feature is the low
leakage which will be found of advantage for tests on receivers that have an
internal ferrite rod aerial.
Permeability tuning of the Oscillator
and output filter modules enables the
complete range to be covered in only eight bands. The hand calibrated near-
logarithmic tuning scale is displayed in a continuous zig-zag pattern, with
scales running alternately left and right. This cuts out much of the tedium
usually associated with tuning about the band-change frequencies. Above
100 kHz (carrier frequency) direct reading incremental tuning gives high
discrimination. Frequency control can also be achieved by externally applied
d. c. or by the use of Digital Synchronizer TF 2170B.
Crystal check points are available at intervals of 1 MHz, 100 kHz or 10 kHz.
Subsidiary check points can be switched in at 1 kHz relative to each of the
main points. The dial of the incremental control can be adjusted to high
accuracy against the crystal check points by means of two independent
Up to 1 V p. d. can be obtained with 100% modulation over all the range and
up to 2 V p. d. is available with c. w. or f. m. outputs. Output is controlled by
cam operated 20 dB and 1 dB step attenuators with voltage and dB
calibration in terms of p. d. across a 50 Î2 load or of source e. m. f. ;
attenuator steps is provided by the carrier level control and meter. Automatic
level control holds the output constant against frequency or range changing.
An auxiliary unmodulated output is available for driving a Counter
Digital Synchronizer TF 2170B.
Internal a. m. up to 100% is produced by a continuously tuned low distortion
covering a frequency range 20 Hz to 20 kHz. This means that the
can be used for r. f., i. f. and a. f. response measurements on a
receiver with no additional equipment other than a receiver output meter.
output is available for external use at terminals situated at the
rear of the instrument. Envelope negative feedback ensures a good
modulation quality up to at least 80%, and modulation depth is independent
of both carrier tuning and carrier level.
The continuously variable a.f. Oscillator
also provides frequency modulation,
and deviation is indicated directly on the modulation meter. Three ranges of
deviation are provided for each carrier range above 200 kHz.
External frequency control terminals can be used to provide dynamic sweep
measurements (with or without internal AM), FSK, phase modulation or digital
External amplitude control terminals can be used for level control
programming or modulation at a very low frequency without phase shift.
Silicon devices are used throughout and emphasis has been placed on
accessibility despite the compact structure and thorough screening. The
instrument has three major horizontal sections; the centre one containing the
oscillators and other circuits can be withdrawn and operated without
Service and User Manual
11.04 Mbytes (11571631 Bytes)
01 May 1979
Scanned document, all readable.
06 January 2019
Chapter 1 GENERAL INFORMATION
1.1 Features ... 10
Chapter 2 OPERATION
2.1 Introduction ... 11
2.2 Controls and connectors (supply and
tuning ... 11
2.4 Controls and connectors (rear panel) 11
2.5 Fuses ... 11
2.6 AC supply cable ... 11
2.7 Battery operation ... 18
2.12 Setting output ... 29
2.19 General notes on connecting Oscilloscope
for dynamic displays ...
Decibel conversion tables ... 35 Simplified block diagram ... 43
Chapter 4 MAINTENANCE
4.1 Introduction ... 45
4.4 Preliminary checks ... 51
4.5 Test equipment ... 51
4.6 Circuit performance ... 51
Chapter 5 REPAIR AND ALIGNMENT
5.1 Introduction ... 56
5.2 Fault finding ... 56
5.3 Additional information ... 67
Index to units • • • • • • • • ■ • • • 81
Chapter 7 CIRCUIT DIAGRAMS
Circuit notes ... ______101
Fig. 7.18 Power unit and regulators .,. 101