RadioBanter - Icom R-75

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RadioBanter (https://www.radiobanter.com/)

- Shortwave (https://www.radiobanter.com/shortwave/)

- - Icom R-75 (https://www.radiobanter.com/shortwave/69548-icom-r-75-a.html)

RHF	April 24th 05 02:16 PM

Dr Artaud,

craigm

April 24th 05 03:54 PM

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

[email protected]

April 24th 05 04:03 PM

I think them Icom's are too high priced for what they are.Too much money
for the amount of bread.Over rated and wayyyyyyyyyyyyy over priced.I
don't want one! They are too fickle too.
cuhulin

[email protected]

April 24th 05 07:43 PM

Thanks for the explanation. I've never really looked at the R-75's
volume control circuit but figured it was pretty standard but I guess
not with the digital control system. Next time I had better study the
circuit before I offer any advice ;-(

Frank

[email protected]

April 24th 05 07:45 PM

Why don't you do everyone a favor and drop your DX-300 in the bathtub
with you when you take your next monthly bath (plugged in of course!)

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