[Elecraft] Wideband qrm above 7.385MHz

[Stephen Prior]

I do wish I'd read this last one more carefully before posting, what I had
intended to say was that the noise only disappears (but only in cw/ssb
modes) below FC = 0.81 kHz.



On 17/11/2010 22:28, "Stephen  Prior" <sjp at sjprior.fsnet.co.uk> wrote:

> 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