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Severe hum that was not there before - SOLVED

 

Hi, can anyone provide some help on a new issue. My Shari Pi3U has been working terrific up until yesterday when I started getting a severe hum on receive. Tried moving the node around the house and still the same. I have the ferrites on the power supply and it is a raspberry supply. Like I said it was working great up until yesterday. Anyone one else have this issue and what was the fix?

73?

Scott VA4SMC
 

Please elaborate on what you mean by "receive".? Is this the audio that you transmit to the node that others hear (RX of the SA818 in the node) or audio that you hear listening to your node (RX of the radio you are using to communicate with the node)?
 

can you post a short video on youtube??
 

Provide us with a few more details.
#0. Receive? The Shari receiving or your HT? (by that- the shari is transmitting you (HT) are receiving.*
#1. any new light bulbs or appliances nearby. In your home.
#2. home or apartment? if apartment how many feet to the next neighbor...
#3. Have you tried:
???? a. another power supply?
???? b. another branch circuit in your home...
???? c. Another HT or mobile rig.

*? If you go into the Simple USB Setup by SSHing into the RPI, you can force the Shari to transmit with no data streaming, which would give you what they call a dead carrier..?

My experience with SHARI's and I've had 6 through my hands, built and set up a number for Blind hams. They are excellent in design (albeit the money) extremely well documented and extremely reliable. I have some running 3-4 years without a single problem.

Merry Christmas,

Larry W8LM
Mulvane, Kansas
 

I swore I replied to you fellas but I have been so sick the last few days maybe I imagined that. By recieve I mean what I hear from Shari on my radio. I have moved the unit throughout my house and no change. I think the neighbors may have gotten something new. I will have to try to do the dead carrier think and see. I will post a video clip when I get better. Thanks so far. The unit worked great up until recently. Well still works great and love it but just hum on receive and no complaints from anyone on my audio.?
 

Sorry fellas, I fell very ill since posting and been fighting it off in bed. Thank you the replies. The hum is present he the Shari is transmitting to my radio. I will post a video when I am able. I also believe it is something new in the area, maybe new Christmas lights or the like. I will try the no data transmit as well and see what that does. Unit works excellent otherwise and worth every dime. I still can believe I got it working the first time. Setup instruction were terrific. I am not the programmie type so I hope I can muddle through this. Thanks again.?
 

Download this document from the files section of this group.

/g/SHARI/files/Listening%20to%20the%20audio%20passing%20through%20your%20Allstar%20node.pdf

This allows you to record all audio passing through your node as individual WAV files.? You can listen to the WAV files of the audio being transmitted to you by your node and determine if the hum is present on the audio being sent.
 

Will do, see what I hear.?
 

On Tue, Dec 13, 2022 at 09:33 AM, Scott VA4SMC wrote:
I swore I replied to you fellas
This site is moderated and each post must be approved by the administrator.. I think he was shoveling snow, because both of your posts saying you were sick appeared right after each other..

Larry W8LM
Mulvane, Kansas, ...... NO SNOW HERE!!
 

Hi, thanks again for the help so far. I recorded the audio through the node and it is crystal clear. The attached file is recorded through my phone from the radio speaker. Any thoughts?

Voice 003.m4a
Voice 003.m4a

 

A spectral analysis of the noise indicates that it is AC power related.? I see peaks at major 299, 409, 683, 955.1228, 1502, 1774 and higher.? See attached JPG file.

The signal with noise your HT is demodulating is most probably caused by the RF from you node being pulse amplitude modulated by a poorly filtered power supply running off the AC line.

One possibility is that yur antenna on the node has failed.? Did you try a different one?

If that is not the proble, I suggest that you start by powering your node off of a battery.? The kind we use to recharge a cell phone works great.?

If that doesn't work, start unplugging anything powered by AC in the room.? It could also be caused by a bad LED or CFL lighbulb.? I once had a problem like this with a CFL lighbulb that would not light but it would still radiate interference when illuminated with RF.

Of course you could always take the node to a different location to confirm that the problem is being caused by a local interferer.

Steve - N8AR

VA4SMC Noise Analysis.JPG

 

Also, try replacing the USB power cable with one known to support more than the current required by the Raspberry PI.? Not all USB cables can provide that level of current, and some fail over time with flexing. Connectors also can fail.

I had noise/hum on a similar Raspberry PI node and discovered I needed a new, better USB cable from my 12V BUCK converter.

David McAnally
WD5M
 

Thanks Steve. Starting this morning after the node connected and announced ip address the hum was so bad the radio was still receiving after the shari stopped transmitting. Only way to stop the noise from the radio was to unplug the node from the wall. I will try the battery.?
 

¿ªÔÆÌåÓý

Are you transmitting in close proximity to the SHARI? If you are try using a very low wattage output. Sometimes this can cause a hum in your transmit audio.

-Fred, KD5FMU
On 12/10/2022 8:51 AM, Scott VA4SMC wrote:
Hi, can anyone provide some help on a new issue. My Shari Pi3U has been working terrific up until yesterday when I started getting a severe hum on receive. Tried moving the node around the house and still the same. I have the ferrites on the power supply and it is a raspberry supply. Like I said it was working great up until yesterday. Anyone one else have this issue and what was the fix?

73?

Scott VA4SMC

--

Fred McGuire Jr.
Henryetta, OK 74437
fred.mcguire.jr@...
 

Tried the battery to power, same as before.?
 

It's not when I am transmitting. It is when the node is transmitting to my radio. Either there is something wrong with the node or the pi. Can't tell.?
 

A couple of comments:

You said "I recorded the audio through the node and it is crystal clear."? I assume this is a file of the audio being sent to your HT created by turning on the recording capability as suggested previously.??

You also said, "Starting this morning after the node connected and announced ip address the hum was so bad the radio was still receiving after the shari stopped transmitting."? But if the node has stopped transmitting and your HT is still receiving then the noise is probably coming from something else, is always there and you must not be using PL.

Please confirm and elaborate a bit on this.
 

Be sure to use ferrite beads on the PI power supply. This help me immensely?

On Thu, Dec 15, 2022, 1:27 PM Scott VA4SMC <smcmbca@...> wrote:

It's not when I am transmitting. It is when the node is transmitting to my radio. Either there is something wrong with the node or the pi. Can't tell.?

?

?
 

¿ªÔÆÌåÓý

IF using CTCSS (and should be) what frequency? May try a different frequency. If your Shari has stopped transmitting, then it sure wouldn't seem to be that since the transmitter is off.

Mick - W7CAT

----- Original Message -----
From: "N8AR"
To: [email protected]
Sent: Thursday, December 15, 2022 11:41:14 AM
Subject: Re: [SHARI] Severe hum that was not there before

> A couple of comments:
>
> You said "I recorded the audio through the node and it is crystal clear."? I assume this is a file of the audio being sent to your HT created by turning on the recording capability as suggested previously.
>
> You also said, "Starting this morning after the node connected and announced ip address the hum was so bad the radio was still receiving after the shari stopped transmitting."? But if the node has stopped transmitting and your HT is still receiving then the noise is probably coming from something else, is always there and you must not be using PL.
>
> Please confirm and elaborate a bit on this.
>
>
>
>
>
>
--

 

If the noise is enough to keep the squelch open on the HT, why not reprogram the frequency on the Shari to move away from the interference?

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