Operation - Heathkit AG-9 Manual

Discrepancies of indicated voltages warrant investigation of the particular circuit involved.
Wiring errors or faulty components may be found with inspection or resistance measurements.
Consider the characteristics of the circuit by rereading the circuit description. An understand-
ing of the theory will aid in locating and correcting difficulties.
If intelligent investigation along the lines indicated does not solve your problem, write to the
Heath Company describing your difficulty in detail, giving all symptoms, voltages and other data
that may aid in correcting your trouble. Be sure to state model and name of instrument, AG- 9
Audio Generator. You will receive a prompt reply to guide your further efforts.
APPLICATION
This instrument lends itself to the many applications in audio laboratories where a near- perfect
sine wave signal within its amplitude and frequency limits is required. Some of the applications
are as follows:
Signal source for bridge measurements.
Signal source for harmonic distortion measurements.
Signal source for external modulation of RF signal generators.
Signal source for testing of audio amplifier for gain and frequency response.
OPERATION
The instrument produces a low distortion sine wave signal voltage of adjustable amplitude and
frequency. To select the desired frequency, adjust the 0-100 knob to the first significant figure,
adjust the 0-10 knob to the second significant figure and turn the multiplier to the desired value.
Example: For a frequency of 35 cycles, set the 0-100 knob to 30, the 0-10 knob to 5 and the
multiplier to Xl.
Example: For a frequency of 72 kc, set the 0-100 knob to 70, the 0-10 knob to 2 and the multi-
plier to X1000.
To select the desired output amplitude into a high impedance load ( 10KSZ or more): Set the LOAD
switch to internal, the ATTENUATOR to the nearest full scale value above the desired output;
adjust the OUTPUT control to give the desired output on the appropriate meter scale.
Example: Desired voltage 7.3 volts. Set ATTENUATOR to 10 volts full scale. Turn OUTPUT
to give a 7.3 volt reading on the 0-10 volt scale.
Example: Desired voltage . 025 volts. Set ATTENUATOR to . 03 volts full scale. Turn OUT-
PUT to give a 2.5 volt reading on the 0-3 volt scale.
To select the desired output amplitude into an external 600
n
load ( 1 volt maximum): Set the
LOAD switch to external and proceed as above.
USING THE DB SCALE
The decibel is a ratio of two power levels and is used in comparative expressions. It may be
applied to voltage levels if the impedances are identical. It may be used as a quantitative indic-
ation for one power or voltage level if the other level is defined. In this instrument, the db
scale is based on a reference or standard level of 0 db = 1 milliwatt in 600
n.
If used with a
600
n
external load, the meter reading is expressed in dbm and the reference level is auto-
matically defined.
If the instrument is used with loads differing from 600
sz
but substantially less than 101M, cor-
rection factors for the voltage reduction in the attenuator and for the db level may be calculated.
If the instrument is used with high impedance loads, the relation between two signal levels may
be expressed as a number of db difference.
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