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ASL 3 and some noise, hoping someone can help

 

Hey guys. HOpe everyone is doing well.
Alright, trying to figure this out and its driving me crazy. I'll give you the repeater setup. I've got a quantar on VHF, and its hooked up to an allstar node. The allstar node is the controller as well. I'm running it in test mode over here. Transmit side is on a dummy load, and the receive side just has a small antenna to keep it on the air.
The pi is in a metal case, and my gut tells me this may be the problem, or at least part of it.
I have the cable going from the 50 pin connector on the quantar that Scott at repeater builder made, and that goes in to a rim lite.
My problem is when I key up, I hear what sounds like a 1KHZ tone and it is driving me totally nuts. I can even record a file if you guys want so you'll hear what its doing. That's probably a somewhat vague description, but here we are. My audio can get through when I talk, but you hear it in the background, and it needs to disappear. I tried moving the cables around and it didn't go away.
Anyone else seen this problem? I'm trying to pin it down. 
Any thoughts?
Any suggestions on what to do would be awesome.

Cheers,

Jed
Gary Cook
 

Are you possibly transmitting an over-modulated CTCSS tone?

Gary


On 12/29/2024 11:08 AM, Jed Barton via groups.io wrote:

Hey guys. HOpe everyone is doing well.
Alright, trying to figure this out and its driving me crazy. I'll give you the repeater setup. I've got a quantar on VHF, and its hooked up to an allstar node. The allstar node is the controller as well. I'm running it in test mode over here. Transmit side is on a dummy load, and the receive side just has a small antenna to keep it on the air.
The pi is in a metal case, and my gut tells me this may be the problem, or at least part of it.
I have the cable going from the 50 pin connector on the quantar that Scott at repeater builder made, and that goes in to a rim lite.
My problem is when I key up, I hear what sounds like a 1KHZ tone and it is driving me totally nuts. I can even record a file if you guys want so you'll hear what its doing. That's probably a somewhat vague description, but here we are. My audio can get through when I talk, but you hear it in the background, and it needs to disappear. I tried moving the cables around and it didn't go away.
Anyone else seen this problem? I'm trying to pin it down. 
Any thoughts?
Any suggestions on what to do would be awesome.

Cheers,

Jed
 

Around 1 KHZ is probably USB port noise.

 
 

Place a ferrite bead on the strain relief on the usb connector as it goes into the rim lite and on the other end around the strain relief that goes into the pi. And it should cure the problem


On Sun, Dec 29, 2024, 12:22 PM Chris Smart via groups.io <ve3rwj=winsystem.org@groups.io> wrote:

Around 1 KHZ is probably USB port noise.

 
 

Jed,
 
I don't know if this will help, but I had a similar noise problem using an AllStar node with a different radio system.  The noise I heard could have been around 1 kHz, but sounded more like a square wave, likely data.  Anyway, it turned out to be a ground loop between the AllStar interface and the rest of the equipment.  I wound up putting isolation transformers between the audio input and audio output of the AllStar node thingy.  That totally solved the problem.  The transformers I used are CALRAD 45-698, as I have a drawer full of them.  Make sure the transformer's cases are grounded.  They're supposedly 600 ohms to 600 ohms.  I don't offhand recall the make of the dongle used in my particular node package, but I recall it having a fairly low driving impedance for the audio output, so the transformers worked well.  Not only that, it sounds good.
 
Burt, K6OQK

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