[ICOM] Icom, Grounds and Mikes

[Sheldon Daitch]

Another option for audio ground loops used with
shielded balanced audio is to connect the shield over
the balanced pair at one end only.

That is, the shield is not connected to both 
pieces of equipment.  Sometimes you have to experiment
with which end to ground, one ground may give a 
better hum value, lower hum, than the other.

Also rack mounted equipment has it own problems, where
the chassis ground is one ground path, the safety 
ground in the power cable is the second path, and the
third path is the rack grounding.  I think the code 
allows the power cord safety ground to be lifted, if
there is another bonding path, such as the 
cabinet or chassis ground, but I might be going out
on a limb on this.


73
Sheldon
WA4MZZ

"David J. Ring, Jr." wrote:
> 
> Jerry,
> 
> Ground loops (in audio) are caused by multiple grounding paths (audio
> ground).
> 
> Sometimes a tape recorder (or some other auxilliary equipment such as
> equalizer or preamps) which using a grounded 3 pin USA electrical plug is
> plugged into a sound board, or recording mixer and it will cause a ground
> loop, but putting a 3 to 2 electrical adapter (and NOT using the ground pin
> to ground the adapter to the wall outlet) will solve this problem.  Now the
> tape recorder will be connected to the recording mixer only by the audio
> cable ground - and NOT by the electrical ground.  This eliminates the ground
> loop.

>