Tom,

I'm not using a laptop, but my desktop has sufficient audio output to drive
line-in levels on the rear of Icom transceivers. If your laptop does not
produce high enough levels (see other responses about impedance matching),
it might be cheaper and "cleaner" to buy a little USB audio sound card
(Turtle Beach has one for $30, about the size of a thumb drive) and grab
audio output from that.
--
-larry
K8UT
"Tom, N3IJ" wrote in message
...
Can anyone suggest a source of a circuit or kit for a mono amp to
increase my laptop's headphone output level to line level?

As a starting point, it would be helpful just to learn what these
levels are. I want to drive a line-level transceiver input for digital
hamming.

Any suggestions would be appreciated.

Tnx & 73, Tom