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Icom R-75
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April 24th 05, 03:54 PM
craigm
Posts: n/a
wrote:
The volume control is at a low signal level so a standard 1/4 watt
resistor or even a 1/8 watt will do just fine.
Frank
Before anyone starts hacking a resistor into the volume control, be
aware of how the radio works. The audio does not go through the
potentiometer attached to the volume knob.
The potentionmeter is used to set a voltage that is then digitized and
use to determine the setting for an electronic volume control. This
method allows the volume to be set remotely and allows the setting of
the control to be read remotely.
The issue with volume at low settings may be the difference between
'off' and the lowest 'on' setting of the attentuator. One could try to
see if finer adjustment is available using computer control. If it is
not possible to get the desired low volume setting, then you will need
to look at different modifications.
The whole control path:
The output of the control is digitized, the internal processor sets the
level for the volume (a digital value), this goes through a D/A to
create a voltage to the attenuator. The attenuator chip adjusts the
volume of the audio. The limitations at low volumes could be anywhere in
this path.
Craigm
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