John,
For connecting ANY radio to HRD (or any other application) for rig
control, You connect the computer serial port TXD to the RXD pin on the
radio, and the RXD of the port to the TXD pin on the radio. Those are
pins 2 and 3. You also must connect RS-232 Signal Ground which is pin 5.
That will get you operational with any (and all) rig control
applications, not just HRD.
Now then, if you were asking about DM780 (for digital modes), the answer
is extended - you must provide a path between headphone out of the radio
to the computer line in soundcard jack - isolation of the grounds
between the radio and the computer may be necessary for noise (hum) free
operation. For audio going the other way, the line out on the computer
connects to mic in on the radio, but through an isolation transformer
and an attenuator to reduce the level by about 10 times - line level
will overdrive the mic input without the attenuator inserted in the path
- a series 100k resistor and a parallel 10k resistor (on the KX3 side of
the 100k) will produce a usable attenuator.
Of course, these things are what is done in the digital interfaces
available from several different sources.
I have spoken in generalities about what those interfaces consist of -
you can homebrew your own or purchase one of the various brands that
suits your operation.
73,
Don W3FPR
On 3/16/2012 5:54 PM, John Lally wrote:
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