[Elecraft] [K3]Advice needed from audio grounding experts

[Paul Fletcher]

Hi all,

I am making up a cable set to connect a Pactor modem to the K3 and wish to
avoid ground loops. The connections to the radio are:

PTT
Power (from the 12v out connector on the back of the K3)
Line in
Line out

According to the schematics one end of the K3 line out isolation transformer
is DC grounded and the line in transformer is DC floating (just to be clear
I am talking about the windings for external connection).

The modem only has 1 ground connection.

I obviously need to connect audio out and ground from the modem to the line
in on the K3 and this will not provide DC ground. My current thinking is
that I connect the modem ground to the 12V ground on the K3 accessory socket
to provide the DC ground. Shielded cables would be used for PTT and the
connection to the K3 line out with the shield disconnected at the K3 end.

Is this the best approach?

Regards,
Paul M1PAF
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