[arm-allstar] USB Cables With the Most Shielding?

[Chris Smart]

I'm using the wall-wart I bought with a Pi 4.

I have a ferrite choak on its cable right at the Wall-wart end, and I am 
not hearing 120 Hz on my audio.


Now it's just the 1,046 Hz I'm sortig out. right now it's absent, as 
long as I don't move anything on the desk. :)



On 2021-06-15 8:55 a.m., "David McGough via ARM-allstar" wrote:
> Hi Chris,
>
> If you're hearing the whine on both RX and TX, the noise is probably audio
> path related; likely a ground loop or other ground noise.
>
> What type of power supply are you using on the RPi board?  I have seen
> situations where very noisy AC switching power supplies (mostly "wall
> warts") would produce a whine that got in the audio. Frequently these have
> significant and detectable AC leakage showing up as common-mode noise on
> the DC power output.  This can rip the USB audio to shreds!
>
> I know numerous different power supply and wiring protocols have been
> developed and adopted by various AllStar users.  I prefer powering the RPi
> board via a DC-DC converter, directly from the radio/repeater power
> source.  I keep all my grounding points a the same physical spot,
> minimizing the potential for ground loops / noise.  Since I went to this
> strategy, my audio noise issues have reliably disappeared.
>
>
> 73, David KB4FXC
>
>
> On Tue, 15 Jun 2021, "Chris Smart via ARM-allstar" wrote:
>
>> Hmm, good question.
>>
>> Right now it's completely gone, but if I move that USB cable a little, I
>> can bring it back easily enough. Sometimes I hear it on TX, sometimes on
>> RX. sometimes both.
>>
>>
>>
>> On 2021-06-14 10:38 p.m., "David McGough via ARM-allstar" wrote:
>>> Hi Chris,
>>>
>>> How is the whine getting into your node---via an audio or RF path??
>>>
>>>
>>> 73, David KB4FXC
>>>
>>>
>>> On Mon, 14 Jun 2021, "Chris Smart via ARM-allstar" wrote:
>>>
>>>> Hi.
>>>>
>>>>
>>>> I'm running an Alinco node radio and the RIM-Alinco device, along with
>>>> the supplied short, very thin USB cable. I'm tired of gently moving the
>>>> bulk of that USB cable around, an inch this way or that, and it going
>>>> from major USB wine (1,046 Hz) to nothing.
>>>>
>>>>
>>>> Do people here have a prefered brand of USB cable with lots more
>>>> shielding, including ferrite? I believe I need USB-A to MINI-B, right? I
>>>> always get mini and micro B confused.
>>>>
>>>>
>>>> I'm also going to put a serial cable on the back of that port so I can
>>>> get the RIM-Alinco much farther away from the transmitter, since it's
>>>> running 5 watts.
>>>>
>>>> I want the best-sounding, quietest node in town, and I"m almost there. :)
>>>>
>>>>
>>>> _______________________________________________
>>>>
>>>> ARM-allstar mailing list
>>>> ARM-allstar at hamvoip.org
>>>> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>>>>
>>>> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
>>>>
>>> _______________________________________________
>>>
>>> ARM-allstar mailing list
>>> ARM-allstar at hamvoip.org
>>> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>>>
>>> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
>> _______________________________________________
>>
>> ARM-allstar mailing list
>> ARM-allstar at hamvoip.org
>> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>>
>> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
>>
> _______________________________________________
>
> ARM-allstar mailing list
> ARM-allstar at hamvoip.org
> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>
> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org