[Elecraft] K3 RFI Susceptibility

[Scott Ellington]

However, if the connector is grounded to a PC board, rather than directly to the chassis, the current on the shield ends up getting INSIDE the radio.  This is the problem with some of the rear panel jacks on the K3.  However, I understand why Elecraft mounted those connectors on the PC board, and simply wrapping the cable around a ferrite core should solve the problem.  (If that works in my shack, it should work almost anywhere.)

73,

Scott  K9MA



On Dec 22, 2010, at 12:18 PM, Jim Brown wrote:

> YES!  Here's the problem -- while that PTT line IS a DC line,  because 
> it is a WIRE, it is also an ANTENNA, so it will carry RF current from 
> your TX and put it into the K3 PTT circuit (and into whatever is driving 
> the PTT circuit). That means we CANNOT treat it as a DC circuit. It is 
> an RF circuit, and must be wired with coax (or something like coax), 
> with the shield bonded to the chassis at each end.  Now, the RF current 
> flows on the coax shield to the chassis at each end, so it does not 
> cause problems with the keying circuit.

Scott Ellington
Madison, Wisconsin
USA