[Elecraft] Wideband qrm above 7.385MHz

[Stephen Prior]

Further to my last posting, I observe now that the appearance of the 'qrm'
depends upon the filter and shift settings, what is observed to be a problem
in AM mode completely disappears in cw/ssb modes, for example this occurs at
and below FC = 0.81kHz.

Stephen G4SJP



On 17/11/2010 22:05, "Stephen  Prior" <sjp at sjprior.fsnet.co.uk> wrote:

> In tuning above 7.385MHz, listening to broadcast stations on AM, I noticed a
> very strong and broadband interference extending to just above 7.500 MHz.
> 
> At 7.385MHz on AM mode I hear a relay click in, and I'm assuming that this is
> the K3 changing over to the KBPF3 which I have installed.  Looking at the P3's
> display, the spectrum which is hf of 7.385 MHz is completely clear of such
> 'qrm' until the VFO goes above 7.385 MHz, and then the qrm appears about 35dB
> above my noise floor, not only above 7.385 MHz, but extending below it to the
> extent that the P3 will show.  Since this is not even observed on the P3 (with
> its maximum span set) until the VFO is tuned above 7.385 MHz, I can't help but
> to think that this is an unexpected artefact.  Removing the antenna clears
> this completely, so it is not internally generated.
> 
> But what is causing it I wonder.  I have never noticed this effect before.
> Since it only occurs above a set frequency and then is apparent below that
> frequency too, to my mind it has to be a fault with the K3 that I haven't
> observed with any previous firmware version.  I am running with latest beta
> for both the K3 and P3.
> 
> 73 Stephen G4SJP