Stridsberg Multicoupler causing Hum on my Feeds?

Status
Not open for further replies.

NFR85

Member
Feed Provider
Joined
Oct 25, 2007
Messages
571
I recently bought 8 port Multicopler and when I hooked them up to my feeds I hear a loud hum. When I take it out replace it with a regular antenna the hum goes away. My question is the Multicoulper is plugged in so I wouldn't notice a loss. The 2 feeds so you can listen.

My question is this fixable or is this suppose to be like that? Stridsberg's website claims no loss with this. In the 8 port I have 2 other scanners plugged in for my personal use non feed.

Lawrence Police Dispatch
Chelsea Police Dispatch
 

N1SQB

Member
Joined
Jan 25, 2003
Messages
2,459
Location
Somewhere On Earth
I use 8 port and a 4 port Stridsberg multicouplers in my shack with 2 different types of outside antennas.
I don't have any issues even remotely close to yours. Could it be a power supply issue? I run mine off of a Rigrunner brand power strip connected to an Astron brand power supply. Again, no issues. Have you tried contacting Stridsberg directly? Those guys over there are great to talk to. I know when I first got mine, I called them and they actually suggested the power supply route versus the provided wall wart.

Manny
 

NFR85

Member
Feed Provider
Joined
Oct 25, 2007
Messages
571
I use 8 port and a 4 port Stridsberg multicouplers in my shack with 2 different types of outside antennas.
I don't have any issues even remotely close to yours. Could it be a power supply issue? I run mine off of a Rigrunner brand power strip connected to an Astron brand power supply. Again, no issues. Have you tried contacting Stridsberg directly? Those guys over there are great to talk to.

Manny
I have it plugged into a surge protector. I sent an email to Stridsberg seeing what I could be doing wrong. I notice on his website he offers RG58U for coax cable and I'm using RX8 Mini so I'm not sure if that maybe the issue the coax cable. I'm not familiar with the products you mentioned I'm not that tech savey sorry.
 

GTR8000

NYS Database Guy
Database Admin
Joined
Oct 4, 2007
Messages
9,067
Location
BEE00
This is a ground loop issue, not a multi-coupler issue.

Put a ground loop isolator on the audio cables between the scanner and PC, and the hum will go away.
 

NFR85

Member
Feed Provider
Joined
Oct 25, 2007
Messages
571

NFR85

Member
Feed Provider
Joined
Oct 25, 2007
Messages
571
I just realized I'm using RX8 Mini and on Stridsberg site they offer RG58A/U. Could that be my problem?
 

gmclam

Member
Premium Subscriber
Joined
Sep 15, 2006
Messages
5,706
Location
Fair Oaks, CA
Ground loop

I concur that this is a "grounding" problem. I suspect that you are getting audio out of the scanner via the headphone jack. The problem is that the "low" side of the audio is connected to ground via a resistor in the scanner.

There are several solutions to this and the best choice depends on your exact setup. You might only need to connect the low side of the audio to a true ground. For me I used the antenna shield as my ground point. Other solutions include adding an isolation transformer on the audio. Regardless of what you do, be sure to monitor/set the audio level into your sound card.
 

NFR85

Member
Feed Provider
Joined
Oct 25, 2007
Messages
571
Does any recommend what type of ground loop isolator I should get?
 

gmclam

Member
Premium Subscriber
Joined
Sep 15, 2006
Messages
5,706
Location
Fair Oaks, CA
The first link you posted is for a power isolation transformer. I doubt that will help. The latest link looks promising, but has the wrong connectors on it. Looks more like something for a guitar.
 

NFR85

Member
Feed Provider
Joined
Oct 25, 2007
Messages
571
The first link you posted is for a power isolation transformer. I doubt that will help. The latest link looks promising, but has the wrong connectors on it. Looks more like something for a guitar.
Could you please provide a link that would work for me?
 

cpetraglia

Member
Joined
Mar 14, 2003
Messages
855
Location
Fairfax, VA
Are your antennas properly grounded? Try and make sure all your equipment is powered by the same 120V outlet. I use a 12V 30A PS to power all my scanners, a few pre-amps and two multicouplers. I have no ac hum issues at all. The problem is likely your connection between the PC and scanners. Is the PC properly grounded?
 

NFR85

Member
Feed Provider
Joined
Oct 25, 2007
Messages
571
Are your antennas properly grounded? Try and make sure all your equipment is powered by the same 120V outlet. I use a 12V 30A PS to power all my scanners, a few pre-amps and two multicouplers. I have no ac hum issues at all. The problem is likely your connection between the PC and scanners. Is the PC properly grounded?
The antenna I got this June was grounded. Nothing else is grounded. Everything is plugged into a surge protector. Sorry for lack of info I'm not tech savvy I have to do alot of research on stuff YouTube.

I looked at the 12V 30A PS and it's not something I know how to do. Way to complicated.
 
Last edited:

cmdrwill

Member
Joined
Mar 30, 2005
Messages
3,678
Location
So Cali
You need to isolate the audio and that requires a ground loop isolator with an audio transformer, with separate input and output windings, to totally isolate the computer ground from the scanner ground. Not all have a real audio transformer in them.

How can you check? There must NOT be any continuity between any of the input side connections to any of the output side connections.
 
Status
Not open for further replies.
Top