[Elecraft] Weird EMI issue... part deux

[James Sarte]

Hello Joe,

Thanks for the reply.  So if I understand you correctly, this noise is
coming from the synthesizer and is normal?

>From conversations with Elecraft tech support, I got the impression that
this should not be occurring as they could not replicate the noise on their
K3's.

It also does not happen when listening to the sub receiver using the AUX BNC
connector.  It only manifests itself when listening to the main or sub
receivers and using ANT1 or ANT2.

I have noticed that if I come across a broadcast signal within that specific
frequency range, then the signal will mask out the EMI completely, and I
can't hear it until I tune past the station.

It would be helpful if I could get a definite answer from the Elecraft
engineers. So far, I have not heard anything from them.  This noise is
actually quite loud for me, and spikes at S7 on the Elecraft meter.

73,
James KC2UEE


-----Original Message-----
From: Joe Subich, W4TV [mailto:lists at subich.com] 
Sent: Saturday, February 28, 2009 6:06 PM
To: 'James Sarte'; elecraft at mailman.qth.net
Subject: RE: [Elecraft] Weird EMI issue... part deux



> I've noticed that when I'm tuning around 4.8 MHz to 5.3 MHz, 
> I can hear EMI in the form of a motorboat sound whenever I 
> turn a front panel knob.  It's most apparent when spinning 
> VFO A or VFO B knobs, but also occurs when turning the filter 
> knobs. 

I have a slight bit of noise when tuning only in that area. 
I believe it to be entirely normal.  I recall  Wayne saying 
somewhere that the DDS operated in the area of 5 MHz and that 
was synthesizer switching noise.  

In my case, the noise is about S1 on an S-meter that was 
calibrated to the XG-2 and is in "abs" mode.  In my case 
the noise is only audible in the main Rx with VFOA or XIT/RIT 
when XIT/RIT is enabled ... or in the sub RX with VFOB or 
XIT/RIT when XIT/RIT is enabled.  The noise is masked by 
band noise with an antenna connected.  It is audible only 
from 4.900 to 5.100 and only noticeable from 4.940 - 5.050 
unless one it looking for it. 

As you say, it is not present when the VFO or RIT knobs are 
at reset ... it is not a problem here. 

73, 

   ... Joe, W4TV