[Drake] Re: Sound Card to Drake

Tue, 24 Sep 2002 08:01:18 -0600

I would suggest using an isolation transformer and some means to use about
1/10  the card output to the T- 4XC. You can, under some circumstances,
get ground loops that will trip the VOX and send hum & noise. Make no DC
ground between the computer and the radio. Also should be an isolation
transformer in the receive line.

   Joe   K5JW

"Barry L. Ornitz" wrote:

> Don, K4BEV, asked:
> > Is there a way to use a computer sound card with a T-4XC?
> > Is a high impedance transformer all that's needed? Or is anything
> needed
> > between the computer and the transmitter?
>
> There is no need for a step-up impedance matching transformer as the
> sound card has a fairly high level output and the microphone input
> only expects millivolts.  The sound card output is low impedance which
> means it is essentially a stiff voltage source.  You will need an
> attenuator to drop the voltage level to something the T-4X expects.
> There is no need to match impedances here as maximum audio power
> transfer is not needed.
>
> At one time Radio Shack sold an "attenuating dubbing" cord that might
> be able to work between the sound card and the rig.  You can also make
> an attenuator using fixed resistors or an adjustable one using a 1 to
> 5 Kohm audio taper potentiometer.
>
>         73,  Barry L. Ornitz     WA4VZQ     [email protected]
>
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