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You can place attenuation ahead of an LNA to improve strong signal handling, but the amount of attenuation needs to be chosen carefully, to take into account the LNA gain and Noise Figure, in order to ensure that the overall system Noise Figure is not any worse than the basic receiver alone.

If you search though the forum you will find many posts on the subject of equalisers, filters and notches.

Here is one example

https://forum.kiwisdr.com/index.php?p=/discussion/comment/5723

For a more detailed analysis of how equalisation can be applied in order to reduce the noise contribution due to intermodulation effects without affecting the basic Signal to Noise performance, see if you can find a copy of this paper on-line.

https://digital-library.theiet.org/doi/10.1049/ree.1977.0028

Regards,

Martin

Ah OK...

Personally, I wouldn't recommend that model, but let's see how it works for you, when used with your antenna.

I'm not sure what device the Noolec is using, but I guess it will be something like the Qorvo QPA4363A.

Rather than issues with MW stations, it's more likely to be issues with possible overload from any strong FM broadcast stations, or other VHF transmitters that may be around your location.

The reasons I suggested a PGA-103 based amplifier for your application are, good IMD performance, low noise figure and rising input impedance, which helps improve signals on the LF bands, especially when using a short antenna. The current consumption is a bit higher at around 100mA. Noolec may have chosen a lower power consumption device, so that it can be used with the limited current available from sdr's with built-in bias tees, many of which have a maximum current rating of around 50mA.

But experimentation is all part of the hobby, so just try it, and be sure to report back with your findings.

If you need any specific help, send me a PM.

Regards,

Martin

I don't think you will be able to get in using WinSCP.

I'm experiencing similar problems since updating the OS version, and WinSCP doesn't provide the option to log in as su. I seem to remember reading a thread about it but can't find it.

Also, with Debian 11 to enable root login, you can add a line to the sshd_config file in /etc/ssh/sshd_config:

Edit the file as root using nano /etc/ssh/sshd_config

Add the line PermitRootLogin yes in the Authentication section

Save the file

Restart the SSH server using service sshd restart

I swear the Linux folks move the goalposts purely to keep us muggles at bay, but if you do find a solution, be sure to tell us, as this is turning out to be a real pain.

Regards,

Martin

Hi Philippe,

That looks like a switching supply to me, probably more than one.

See if the bands of interference repeat at regular intervals, typically at harmonics of the actual switching frequency, 60, 100, 160kHz.

Unfortunately, if carried by the mains supply they are connected to, the radiated noise can be propagated over a large area, and you will find peaks and troughs in the radiation pattern, depending on the length of wire that are attached to.

I have recently been trying to locate some broadband VDSL interference centred on 3MHz, that is emanating from houses at least 0.5km away from the KiWi site, but fed with overhead copper phone lines.

I've been using SDR Angel and its "heat mapping" option, to perform "drive by" surveys of the area.

I use a magnetic mount active whip and GPS antennas, connected to an RTL SDR V4 dongle and laptop.

The more orange / red or brighter the "blob" plotted on the map, the stronger the signal level.

The KiWi probably has most of the required hardware to be able to do this, but KiWi recorder may be more suited.

Regards,

Martin

For transmit purposes, it's all about antenna efficiency, and radiating as much of the applied RF power in the direction you want it to go.

For reception purposes, it's all about the Signal to Noise Ratio, and a good transmit antenna may not always be a good receive antenna.

The natural noise floor on the LF bands is relatively high, especially in urban areas, and even quite small antennas can still be performance limited by the surrounding noise floor.

Rather than concentrating on large antennas, you may get better results with a smaller antenna in an electrically quieter location. Some experimentation is required, to get the best results.

Balanced antennas are generally better than unbalanced ones, and end fed wires have a reputation as being noise magnets.

If you do wish to install one, this diagram may provide some suggestions about minimising unwanted noise.

Regards,

Martin