Re: One more kfs reception report after attenuators are in position again...


Rob Robinett
 

Thanks Ulli.


On Thu, Jun 17, 2021 at 6:27 AM ON5KQ <ON5KQ@...> wrote:
0h15 (just after midnight California time)

kfs report:
- port 8073
*no OV-indications
*background noise on dead bands (10m,12m...) is too high. Instead of -100dbm noiselevel, in this condition the kiwi-sdr should show -110..-108dbm at maximum (AMwide S-meter reading). As the receiver noise is roughly -115...-117dbm this would make sure that the background noise is at least 6db higher than receiver noise.
Although overloading is not visible is not visible, the bottom 10db sensitivity is useless and available dynamic range should be used for strong signals.
So additional 6db attenuation would improve the situation on low frequencies at night without effecting 10m sensitivity at all during the day.
* slight BC-IMD visible at low frequencies - every 10kHz carriers...
*20db attenuation notch on 3475kHz affects 80m CW, especially weak DX-reception (weak signals cannot be heard!)

-port 8074
*no 0V indication (ADC clipping) visible
*sensitivity on 10m is just right - background noise of -108dbm on 10m is ok
*strong IMD on low frequencies, due to signal distribution fault. Although overall signal strength is lower than on 8073, the IMD is much stronger
*1.8Mhz up to 80m (3.5Mhz) cannot be used due to the IMD at night

-port 8075
*no 0V indication
* background noise level on dead band excellent (-109dbm is just about right)
*no IMD on lowbands
*typical noise from the cellphone cabin is not visible at night although 8843 noise level is low this night (-100dbm at AM-wide)
*unfortunately no 160m...
*overall very good antenna and good set-up

- port 8076
*no 0V indication
* background noise level on dead band excellent (-110dbm is just about right)
*no IMD on lowbands
*unfortunately not usable below 3.5Mhz due to high pass filter
*typical noise from the cellphone cabin is not visible at night, in the 8Mhz band, 8843 noise level is much higher than on 8075 antenna (-89dbm at AM-wide due to high QRN)
*noise level on the low bands is by far the highest on all antennas. I wonder how often the kfs operators switch antennas at all....hi
*very pronounced directivity would be good for hamradio however...

regards,
Ulli, ON5KQ



--
Rob Robinett
AI6VN
mobile: +1 650 218 8896

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