In article ,
John Smith I wrote:

Telamon wrote:
...
Either one will not be an effective block unless they are designed to
prevent passing common mode RF noise. It takes very little in stray
capacitance or mutual inductance to go around the opto-isolator.


If you are an electronics engineer, I'd venture you are a damn poor one.
The opto-isolation I proposed would be about 10,000x more isolation
than an audio xfmr.

Coupling of rf noise though the audio xfmr is just a question of "how
much?" Indeed, I'd be surprised if they even provided proper shielding
(grounded metal sheet over inner winding with ends of sheet insulated
from each other) of one winding from another!

If the core material is ferrite, like in the cheap china junk, I'd throw
it away for such uses. Silicate-steel laminations might be usable when
rf is a problem ...

You are very weird and you have poor comprehension. Go back and re-read
the thread and you will find that I did not recommend the transformer.
My post of a few lines stated that the opto-isolator would be not any
better than the transformer. I don't know where you get your ideas from
but you are one very confused individual.

The reason another poster thought the transformer would help is because
the problem was created by a ground loop. If the problem was a ground
loop the transformer or opto-isolator would help.

My thinking was always that it was a common mode noise problem with the
switching noise from the laptop getting to the radio through the
connecting cable. A ferrite clamp on core is a good solution. Ferrous
metals are much lower in inductance value than the ferrite and would not
work as well for a similar size core.

Why do you bother to post if you have no idea what you are talking about?

--
Telamon
Ventura, California