Marconi Instruments TF 2502 - Chapter 1 GENERAL INFORMATION; Introduction

General information
1.1 INTRODUCTION
TF 2502 is a 50 Q absorption power meter for measurements from d. c. to
1 GHz in ranges of 3 Wand 10 W full-scale. It is one of a series of similar instru-
ments having different power ranges.
The design is based on thin-film and microwave techniques and employs a
thermocouple detector in series with a terminating load. Incident power is sampled
by tbe detector and the resultant e. m. f. is displayed on a meter calibrated in terms
of totalincident power. This method gives a reading of true mean power irrespective
of waveform and makes the instrument particularly suitable for measurim:; the output
of a.m. or pulse transmitters. A socket is provided to allow the demodulated signal
to be monitored on headphones or an oscilloRcope.
The disadvantage of the long time constant inherent in a thennocouple meter is
overcome by the provision of an auxiliary fast response diode detector with a separate
small meter. This allows you to quickly tune a source under test for maximum output
before measuring its power level on the main meter.
Fig. 1.1
R.F. Power Meter TF 2502
2502 (1)
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