OPERATION
Clips for Measuring Filament Voltage
Fig. 15. Location of Controls
Loudspeaker.
The phone plug of a Loudspeaker, such as
Radiola Loudspeaker Model 100 or Radiola Loudspeaker Model 104,
should be inserted in the second stage telephone jack (Fig. 15). The
first stage telephone jack may also be used for Loudspeaker operation
at reduced volume.
Filaments.
Pull out the Filament Switch (Fig.
15).
Turn the
"
VOLUME CONTROL
"
to "
LOUD
."
Turn the "
BATTERY SETTING
"
control
to a position where good results are obtained. With new "A" batteries,
this point comes at about 3.5 on the scale. The life of the Radiotrons
will be considerably lengthened by setting the pointer of this control
as far to the left as practicable and then advancing slightly to improve
the quality of reproduction. This control may be advanced from time
to time as the "A" batteries grow weaker.
Voltmeter.
In order to obtain the maximum useful life of
Radiotrons and batteries, it is recommended that a high-grade high-
resistance voltmeter be used to adjust the filament terminal voltage to
a value not exceeding 3.3 volts. This voltage may be measured by
inserting the leads of the voltmeter, preferably equipped with phone
tips, into the filament voltmeter jacks J (Fig. 13). With the "
VOLUME
CONTROL
"
pointer at "
LOUD
"
and "
BATTERY SETTING
"
pointer at "
OFF
",
insert the voltmeter leads not more than one inch into the filament
voltmeter jacks, the lead from the positive ("+ ") terminal entering the
right-hand jack. Then advance the "
BATTERY SETTING
"
pointer slowly
until the voltmeter registers proper value, which should be as low as
will give good
16