Ground Loop Isolation - for cable TV ?

redrabbit · 25th May 2007, 06:45 AM

Yes, I had audio hum resulting from the coax cable's ground, and resolved it with an Iso-Max VRD-1FF -- inline to the cable box.
Hum is 95% gone.....that's acceptable for me.

HOW DO I MAKE something similar ?
Is it just inline caps ?

Why can't I find any DIY ideas for this ?.....(besides the common back-to-back 75/300 ohm antenna transformers.)

=FB=

AndrewT · 25th May 2007, 04:16 PM

Hi,
the hum buster may be an audio transformer to provide isolation between the equipment.

Juergen Knoop · 25th May 2007, 06:29 PM

the so called antenna isolation transformers sold here rely on capacitor coupling.
No transformer inside the tranformers...

redrabbit · 25th May 2007, 11:05 PM

I still don't understand why there isn't an easy diy solution ?
If they're caps, what values ?

Those Jensen isolators have a stated frequency that they filter/isolate, which I guess is crucial, so as not to degrade the video signal.
I believe they use caps too.

Many of us use ground isolation in our audio projects including me.
(10ohm resistor, and 100nf cap between earth and circuit)

=FB=

Juergen Knoop · 26th May 2007, 02:50 AM

of course you can DIY. The absence of a dedicated internet site doesn't mean one can't do it.

Choose a 100pF or larger ceramic for the inner conductor and something in the nF range for the shield.
regards

alexmoose · 26th May 2007, 02:54 AM

Quote:

Originally posted by redrabbit

Why can't I find any DIY ideas for this ?.....(besides the common back-to-back 75/300 ohm antenna transformers.)

=FB=

Whats wrong with this solution, it is what I used in my dorm room, worked great!

25th May 2007, 06:45 AM	#1
redrabbit diyAudio Member Join Date: Oct 2004	Ground Loop Isolation - for cable TV ? Yes, I had audio hum resulting from the coax cable's ground, and resolved it with an Iso-Max VRD-1FF -- inline to the cable box. Hum is 95% gone.....that's acceptable for me. HOW DO I MAKE something similar ? Is it just inline caps ? Why can't I find any DIY ideas for this ?.....(besides the common back-to-back 75/300 ohm antenna transformers.) =FB=

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25th May 2007, 04:16 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, the hum buster may be an audio transformer to provide isolation between the equipment.

25th May 2007, 06:29 PM	#3
Juergen Knoop diyAudio Member Join Date: Jan 2007 Blog Entries: 3	the so called antenna isolation transformers sold here rely on capacitor coupling. No transformer inside the tranformers...

25th May 2007, 11:05 PM	#4
redrabbit diyAudio Member Join Date: Oct 2004	I still don't understand why there isn't an easy diy solution ? If they're caps, what values ? Those Jensen isolators have a stated frequency that they filter/isolate, which I guess is crucial, so as not to degrade the video signal. I believe they use caps too. Many of us use ground isolation in our audio projects including me. (10ohm resistor, and 100nf cap between earth and circuit) =FB=

26th May 2007, 02:50 AM	#5
Juergen Knoop diyAudio Member Join Date: Jan 2007 Blog Entries: 3	of course you can DIY. The absence of a dedicated internet site doesn't mean one can't do it. Choose a 100pF or larger ceramic for the inner conductor and something in the nF range for the shield. regards