G8JNJ

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

Each of the DXE filters contains two filtered Halo HFJ-1G46ERL RJ45 sockets wired back to back on a small PCB.

Pin 10 seems to be left floating in the DXE design.

Regards,

Martin

Everything is inside the box as shown by the dotted line.

I should have clarified the way it works a bit better.

Pushing the mouse wheel down whilst rotating it enables the opposite mode to the default that has been chosen. in OpenWebRX.

Having the possibility to tune using the mouse opens up other possibilities such as making your own VFO knob, using the optical encoder recovered from a scrap mouse, or buying one of the more expensive ready-made commercial items.

If it could be implemented in a way similar to that of OpenWebRX , then it would still retain the mouse wheel zoom option for those who prefer it, but offer an alternative for folks who would like to use mouse wheel tuning.

Try it and see for yourself.

http://wessex.hopto.org:8060

If you open up the settings pane in the control panel, you should see the "Hold mouse wheel down to tune" tick box. Also set the tuning step size in the controls section, 500Hz or 1kHz is useful for SSB, as most folks use 'rounded up' frequencies.

I'm not specifically requesting this feature, as I don't wish to add to John's already massive workload of much more important issues, but I can understand the appeal of it.

Regards,

Martin