Mike and all,
Part of what you are saying may be correct - BUT, the K3 Line-in and
Line Out are NOT for balanced lines.
If you have an early K3, there may be inductors in the ground path (and
they may still be shown in the schematics). Those inductors were
removed in later K3s and the Line-in and Line-out shells are now indeed
grounded.
Those inductors in the ground path can (and should) be removed (should
you have an earlier K3 with them still in circuit). See "Improving the
Immunity of Rear Panel RS-232 and Audio Connectors to RF" at
http://www.elecraft.com/K3/mods/ELECRAFT_Application_Note_Improving_the_Immunity_of_the_Rear-Panel_KIO3_RS232_and_Audio_Connectors_to_RF.pdf.
If you are dealing with a later K3 and have such problems with the
SignaLink interface, follow Mike's instructions to combine the separate
grounds into one bonded ground.
73,
Don W3FPR
On 3/18/2015 6:36 PM, [email protected] wrote:
ALERT!If you use an ethernet box to switch between a SignalinkUSB box and another
modem, you may be in for some surprises.The Tigertronics SignalinkUSB cable
SLCABK3 brings out 6 of the wires to the RJ45 connector. EACH of the Line In, Line
Out, and PTT output have their own SEPARATE grounds for the sleeves of the
connectors.Internally, the SignalinkUSB box joins them up to work well. HOWEVER,
the K3 Line In, and Line Out jacks are not sleeve grounded to the chassis, and are
set up as balanced Input and Output.If you wire up a modem, such as the SCS PTC
series or other, make sure that you wire the 3 grounds out to the corresponding
pins of the RJ45 connector or you won't have it work right.Use your Ohmmeter to
verify that each of the SCCABK3 sleeves are grounded to the modem through the
switch.Neglecting that could have you spinning your wheels for a long time.Mike
VE3EQP/W4 .....>
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