Operating instructions

LOCAL OPERATION

3-13

Rx=Tx Offset Freq: Hz

A setup option within the Tx TEST mode (Rx=Tx) will set the signal generator used for

receiver testing to the measured frequency of a transmitter being tested. An Rx=Tx offset

frequency entered here will cause the signal generator frequency to differ from the measured

transmitter frequency by the offset frequency. To enter an offset frequency, press the adjacent

soft key, key in the appropriate digits, using the minus key and the decimal point key if

necessary, then use the relevant terminator key, (MHz, kHz or Hz). A positive figure will set

the signal generator frequency above the measured transmitter frequency, while a negative

figure will set the signal generator to a lower frequency than the transmitter.

RF Level In: EMF/PD

The selection is made by toggle action of the soft key. The PD or EMF flag is shown against

output levels displayed as voltage or dBµV.

With the EMF option selected, the displayed RF output level shows the open circuit voltage

available at the RF output connector.

With the PD option selected the displayed RF output level shows the voltage that would be

present across a 50 Ω load.

Return

Returns to the Help/Setup Menu.

Setup page 2

This page allows the following optional settings to be selected:-

Audio Level Measured in:

Repeated presses of the adjacent soft key will toggle through

Volts, dBm, dBV or Watts and

highlight the selection in inverse video.

The level of a signal applied to the AF input socket is measured in terms of the selected option.

This will then apply to all subsequent measurements.

The indicated output level from the AF generators is not affected by this selection.

Audio Input Impedance Match:

The impedance selected by this key is used by the Service Monitor to calculate and display the

measured voltage as a power (in dBm). Note that the impedance of the AF input remains high. To

obtain an accurate measurement the necessary terminating impedance must be added externally.

Audio Input Impedance:

This key is only active if the 600 Ω interface option is fitted. Pressing it will toggle between the

600 Ω balanced input impedance or the standard high impedance. The AF input connector on the

front panel is used in either case.

Audio Output Impedance:

This key is also only active if the 600 Ω interface option is fitted. Pressing it will toggle between

the 600 Ω balanced output impedance or the standard low impedance. The AF generator output

connector on the front panel is used in either case.

20 dB audio attenuator:

This key is also only active if the 600 Ω interface option is fitted. Repeated presses of it will insert

or remove a 20 dB attenuator from the output circuit of the audio amplifiers. With the attenuator

in circuit the maximum output is limited to 400 mV. The adjustment resolution is increased to

0.01 mV below 40 mV and to 0.1 mV from 40 mV to 400 mV.