MARCONI
INSTRUMENTS
F.M. Signal Generator	Type TF 1066B
facility, the stepped control being particularly suitable for rapid spot checks during production testing.
RACK MOUNTING
An alternative version, IF 1066B/1, is available for, mounting in a standard 19-inch rack.
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Frequency range: 10 to 470 Mc/s
Carrier generated directly at output frequency
' Frequency stability: 0.0025
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Stepped as well as continuously-variable incremental tuning
Internal modulation at 1 and 5 kc/s
THE MARCONI F.M. Signal Generator TF 1066B covers the range 10 to 470 Mc/s. Direct carrier-frequency generation without multipliers ensures the complete absence of spurious sub-harmonics in the output, and its direct-reading incremental tuning system brings ease and accuracy to bandwidth measurement.
Stability and purity of signal are enhanced by the use of a rigid cast r.f. box and a transistor-regulated d.c. filament supply for the r.f. oscillator; and there are preset potentiometers to simplify setting up and to enable you to choose your own values of stepped incremental shift.
F.M. deviation is variable up to 100 kc/s and a.m. depth up to at least 40 % Modula
tion can be applied internally at 1 or 5 kc/s, or externally between 30 c/s and 15 kc/s. For both internal and external modulation, f.m. deviation or a.m. depth is directly indicated.
The open-circuit output voltage is continuously variable from 02 V.V to 200 mV and is derived via a source impedance of 50 ohms; the level of output is controlled by a piston attenuator equipped with a 4k-inch dial bearing two scales, one calibrated directly in units of voltage and the other in decibels relative to I µV.
APPLICATIONS

Although the prime function of the TF 1066B

is the production ofc.w. and ff m,
signals itcan,
in addition, provide amplitude-modulated outputs. These dual modulation facilities, coupled with its wide frequency and output ranges, make the TF 1066B outstanding as a general-purpose instrument capable of the broadest application.
It will perform all the exacting tasks required of a precision f.m. generator in testing and aligning v.h.f. and u.h.f. f.m. receivers, whether for broadcast or communication systems, fixed or mobile. Of special advantage in bandwidth measurement is its direct-reading incremental tuning

R.F. OSCILLATOR

The heart of the TF 1066B Generator is its craftsman-built r.f. unit employing the Marconi-patented system of contactless waveband selection in a highly developed form. It is this system, supported by such measures as fully stabilized h.t. and l.t. supplies, which yields the excellent frequency stability figure of 0-0025% over a 10-minute period; this is equivalent to a drift of less than 800 c/s per minute at 300 Mc/s-a point of performance that allows the user to take full advantage of the incremental tuning facilities even when making protracted measurements.
INCREMENTAL TUNING SYSTEM
An outstanding feature of the TF 1066B is its incremental tuning system by which small, precise changes can be made in carrier frequency, either continuously variable or stepped, and read directly from a panel meter. The stepped control provides six preset incremental shifts up to ±100 kc/s -a feature which greatly facilitates rapid checking of receiver bandwidth during production testing. Both incremental frequency controls vary the d.c. applied to the reactor used for frequency modulation.
In addition to the incremental tuning arrangements there is a fine frequency control for setting the Generator accurately to the centre frequency of a narrow-band system under test.
MODULATION
Frequency modulation is applied via a ferrite reactor coupled to the oscillator tuned circuit. For amplitude modulation, variation of carrier amplitude is obtained by applying the modulating voltage directly to the anode of the r.f. oscillator.
Modulation is monitored by a meter with two scales, both of which indicate either f.m. deviation in kc/s or a.m. depth in percentage, depending upon the type of modulation in use.