Audio transformers needed

[Jim Wiley]

Looking for a pair of audio transformers, something in the range of 600
to 2400 ohms impedance, 1:1 ratio (equal primary and secondary impedance).

These will be used to remove a ground-loop problem between my computer
and other equipment.  I prefer something that will handle wide range
audio, perhaps 30 to 15,000 Hz (wider is OK, but must be at least 40 Hz
on the low end, and 12,000 Hz on the high end).

These are typically about 1" to 1 1/4" square and 1 1/2 to 2" deep, in a
deep-drawn steel shell with 4 6-32 mounting studs.  I prefer a matched
pair, but individual units are OK as long as they have approximately
same configuration.

If you have something that may work, please let me know and perhaps I
can arrange a trade or purchase. Removed from military or boat anchor
equipment is OK, need not be new

Please reply off list, in other words, directly to one of my emails,  
shown below, to cut down on traffic to those not interested in this subject

Reply to:   [hidden email], or [hidden email]

Thanks, and 73

- Jim, KL7CC
Chugiak, AK (near Anchorage)


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[Ed-2]

Two that I have used with good results are “Triad TY-304P” and “Etal P-3356”.  These are quality
transformers and are readily available.  Just enter the part number in your search engine.

Radio Shack also has several available that should work just fine.

Just a note:   A transformer is not required for interfacing to a K3 Line in/out.  Transformer
isolation is supplied internally.
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[Jim Brown-10]

On 7/7/2013 12:10 AM, Jim Wiley wrote:
>
> These will be used to remove a ground-loop problem between my computer
> and other equipment.

You do NOT need a transformer.  What you DO need is simple bonding.

http://audiosystemsgroup.com/HamInterfacing.pdf

There are two simple steps.

1) Get power for all of the radio equipment, and for all equipment
connected to your radio equipment (computer, computer monitor) from the
same 120V electrical outlet.

2) Bond from chassis to chassis of all equipment that has an unbalanced
signal connection to your radio equipment (rig, computer, audio
processing, etc.) with short, fat copper. I use the braid stripped from
good transmitting coax (RG8), which is typically the equivalent of #10.
And, of course, add a short fat bond from the rig to the station ground.

That's all you need. A chassis connection to most laptops can be found
at the connector retaining screw of DB-connectors (SVGA, LPT, RS232).

There is, by the way, no such thing as a "ground loop." The REAL cause
of the problem is simple leakage current within the AC power system. See
the link above for an explanation.

73, Jim K9YC
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