[Elecraft] Switching between Signalink and other modem.

[Don Wilhelm]

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, mpupeza at sympatico.ca 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 .....> 		 	   		
>