[Elecraft] OT Hearing HRD Communicate w/K3

[Elecraft K3]

Hi Jim;

Thanks for the reply.   HRD must be the source of the signal.  It disappears mid croak when I quit HRD.  That's not to say HRD is to *blame*. 

I have read your excellent and comprehensive treatise on RFI and that is what prompted me to suspect a "SERIOUS multi-turn ferrite choke" was needed.  I am embarrassed to say that I am a graphic designer that is new to the hobby and your article goes over my head in a hurry!  I was hoping for specific suggestions about a manufacturer, product and number of turns.

I suspect the "problematic cable(s)" is the coax coming in from the antennas.  It's not my tuner that is the problem because I tried completely taking it out of line and the noise persists.  I'm not sure how to check the USB to serial cable.  The noise goes completely away on RX when the antenna is disconnected.  I have no way to check on TX without an antenna.

Thanks again for taking the time to respond.

73 de Eric, KG6MZS


On Mar 18, 2011, at 3:18 PM, Jim Brown wrote:

> I strongly suspect that HRD is NOT causing this problem, but rather a 
> problem with either the computer or the K3 generating RF trash on the 
> serial connection. This is not uncommon, and generally is the result of 
> a Pin One problem at one or more of the data and/or audio ports. 
> Virtually all computer sound cards and data ports have Pin One problems.
> 
> IF the trash is coupled by RF to the antenna(s), a SERIOUS multi-turn 
> ferrite choke on the problematic cable(s) should help.  The choke should 
> be tuned (by varying the number of turns) to cover the frequency range 
> where you are hearing interference.
> 
> Study http://audiosystemsgroup.com/RFI-Ham.pdf
> 
> 73, Jim K9YC
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