On May 16, 2005, at 8:24 PM, John Merrill wrote:
> Anyone using this program for rtty? What kind of interface are using
> besides a commercial one?
Yes!
I built one. Mine is pretty simple. I have a 1k/8ohm audio
transformer on the receive side. The 8 ohm side plugs into the
headphone jack. The 1k side goes to the line input of my PowerBook. I
also have a 300 ohm pot connected across the 8 ohm side to another
jack so I can plug in a speaker or headphones. (you do want to hear
the audio, just not very loud)
The transmit side is a little more complicated. I terminate the
headphone output of the powerbook with two 25 ohm resistors, one for
each channel. If you have a line output, you might not need the
termination. I tap off the left (tip) channel and pass it through a
500 ohm resistor and a 5k pot to a 600/600 ohm transformer. The
output of the transformer goes directly to the rig microphone jack.
This is in a plastic box, so there's no ground loops -- the coupling
through the transformers to the rig is all magnetic.
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
_______________________________________________
RTTY mailing list
RTTY@contesting.com
http://lists.contesting.com/mailman/listinfo/rtty
|