[Ham-Mac] Mod to SignaLink SL-1+ for USB Interface

[Steve Lawrence]

I use three 600 ohm to 600 ohm telephone modem transformers to  
provide hum isolation between an FT1000D and an iMic (and then on to  
a G4 USB port). Two are for stereo audio and one is for the rig's mic  
line in. Connected across my headphone jack, there is no change in  
the audio level in the cans. At the mic input, the level control is  
left the same as for SSB.

The iMic input is set to Line Level (with the switch towards the mic  
symbol.) Note that Griffin claims:

"Most built-in computer audio supports a maximum of 16bit sampling,  
while the iMic hardware samples internally at 24bit."

The current iMic version is only 16 bits while earlier models were 20  
bits. Checking the input source on the config screen in cocoaModem  
will tell you what you have. If yours is 20 bit, hold on to it. They  
don't make it anymore.

If you look at the signal path in the Signal Link schematic  
referenced below, you'll see that it's simply 600 ohm telephone modem  
transformers with padding resistors (which have not been necessary  
for me).

http://www.tigertronics.com/sl_mods.htm

73 - Steve WB6RSE