[Elecraft] OT Hearing HRD Communicate w/K3

[Elecraft K3]

Hi Joe;

Thank you for the reply.  As I mentioned to Jim , the noise completely disappears on RX when the antenna is disconnected.  This leads me to suspect that the RFI is coming in on the antenna cable.  Does that sound right?  If it was coming in on the USB to serial I would expect to still hear it when the antenna was disconnected.

73 de Eric, KG6MZS


On Mar 18, 2011, at 3:22 PM, Joe Subich, W4TV wrote:

> 
> Replace the cable on your USB to serial interface and make sure
> your K3 has all of the "RFI" mods, particularly those involving
> the KIO3.
> 
> What you are hearing is common mode noise from the USB cable that
> is being radiated into your antenna or being conducted via the
> RS-232 cable.
> 
> 73,
> 
>   ... Joe, W4TV
> 
> On 3/18/2011 5:51 PM, Elecraft K3 wrote:
>> Hello Wise and Powerful Reflector;
>> 
>> I am experiencing a confounding problem with Ham Radio Deluxe, Digital Master 780 and my K3.  I've determined that HRD polling the K3 is introducing a croaking pulse-like noise into my signal chain.  I know it is HRD because if I quit out of HRD, no noise.  In fact, if I merely click and hold on the Radio pane in Digital Master 780, the noise ceases.  Additionally, if I click and hold on the Sound Card Pane, the noise also ceases.  I assume this is because that action arrests HRD's polling of the K3.
>> 
>> I hear it on transmit and I know it is going out with my signal because I've tuned my TH-F6A to the transmit frequency and gone out on the deck and heard it in the TH-F6A's receiver.
>> 
>> I assume the noise is coming in on my various antennas because pulling the antenna jack causes the noise to cease.  Pulling the audio cables does nothing.  I hear the noise on the K3's RX on some bands but not on others.  Where I really hear it is on the TX monitor when the Line in is set high and the computer's sound card is set low.  If I try the reverse - set the Line In to 2 and the sound card on the computer to 100, I can barely hear the noise.
>> 
>> That has been my workaround when on PSK lately but I would like to eliminate this noise altogether and keep my signal clean.
>> 
>> Interestingly this doesn't show up as distortion on my external IMD meter from KK7UQ.  I guess the noise is too wide and not a distortion product.
>> 
>> I'm thinking a ferrite toroid on the antenna coax might solve this.  I tried one of those clip on ferrite dealies with no joy.  So the question is: does anybody on the list have any experience like this?  Is a toroid a good idea?  Which one and how many turns?
>> 
>> TIA
>> 
>> 73 de Eric, KG6MZS
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>