http://elecraft.85.s1.nabble.com/Wideband-qrm-above-7-385MHz-tp5749686p5749752.html
I do wish I'd read this last one more carefully before posting, what I had
> 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" <
[hidden email]> 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