Marconi TF 144H/6S Generator
The TF 144H series of signal generators give c.w. and a.m. outputs suitable
for the standard measurements and tests on equipment operating in the m. f.
, h. f. , and lower v. h. f. bands. Their good frequency stability and high-
discrimination tuning are of particular advantage in testing narrowband
covers 10 kc/s to 72 Me/ s in twelve ranges. Eight of these
ranges follow a straight-line frequency law and have a frequency cover of 2:1;
the remaining four have a slightly greater range and one of them covers the
medium-wave broadcast band. A large effective scale length is provided on
the main tuning dial which has separate hand-calibrated scales for each
range. Its discrimination is such that a 2% frequency change on any band
occupies more than a quarter of an inch of scale length. Frequency accuracy
is ±1%, but for greater accuracy there is a built-in crystal Calibrator
gives at least 90 crystal check points throughout the twelve ranges.
An 8: 1 reduction drive from the main tuning control enables easy and precise
adjustment to be made, and a linear logging scale with 100 divisions attached
to the main tuning control facilitates interpolation between any of the main-
scale divisions. In addition to the logging seals, a fine tuning control is
provided which is operative above 80 kc/'S and enables incremental
frequency adjustments to be made, with complete freedom from backlash, up
to ±0. 5% of the frequency in use.
Modulation can be applied from an internal 400-c/ s to 1000-c/ s Oscillator
from an external source. In both cases, depth is variable up to 80% over most
of the frequency range.
There are two r.f. signal outlets. One supplies an output e.m.f. switchable
between 2 and 2. 75 volts (monitored by the meter) at very low impedance
while the other supplies a variable e.m.f. between 2 (jlV and 2 volts via coarse
and fine 50-ohm attenuators; the output range may be extended down to 0.2
[0.V by using the 20-dB Attenuator Pad accessory. A system of automatic level
control keeps the carrier level constant throughout wide frequency changes.
Designed for operation from either a. c. mains or battery supplies the
instrument is available in forms suitable for bench or rack mounting, as
Service and User Manual
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06 January 2019
OPERATION ... 24
MAINTENANCE ... 55