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PSU Noise with #airspyhfplus #spyserver

andrea ottaviani
 

Hello.
If I connect HF Plus directly it receives good, if I connect from the server (Orange) I see all this noise and spurs.
I tried disconnecting everything.
Some time ago there have been strong lightning, about a month and this has happened since. What do you suggest?
can you try my server sdr: //ik0mmi.ddns.net?
Thanks
best 73 of IK0MMI
Andrew

h. garcia
 

I had something similar (noise spikes) when connecting the antenna directly to HF+.

It became much better when inserted a 1:1 balun with galvanic isolation (that is: distinct coil windings).

For my tests, I used NooElecs 1:9 balun, not ideal, but worked nevertheless.

Some ideas:

I haven't tested yet, my guess those very cheap CCTV baluns may be used for experiments.

Old network cards (those that used to have both BNC and RJ45 outputs around 1990-97) often have a boxy component near the RJ45 jack that looks like a relay. These are actually combined 1:1 isolation balunsĀ  (one each pair) enclosed in a single package. A friend reported they worked very well in LF to HF range.

On Tue, Oct 22, 2019, 16:23 andrea ottaviani via Groups.Io <mmh=libero.it@groups.io> wrote:
Hello.
If I connect HF Plus directly it receives good, if I connect from the server (Orange) I see all this noise and spurs.
I tried disconnecting everything.
Some time ago there have been strong lightning, about a month and this has happened since. What do you suggest?
can you try my server sdr: //ik0mmi.ddns.net?
Thanks
best 73 of IK0MMI
Andrew

andrea ottaviani
 

ciao Garcia.
Thanks. I connected the orange server directly to the battery and the spikes are still there!
If I connect the HF+ receiver directly to the PC everything disappears.
My Orange Pi plus is fucked, its voltage regulator is gone.

best 73 de IK0MMI
andrea

Ron Liekens
 

Why not use a standard 1:1 balun or/and a galvanic isolator? Running a 1:9 balun on a 50 Ohm coax and anntenna on a 50 Ohm Airspy input seems not logical.

73' Ron

andrea ottaviani
 

Great advice, I'll do it

Many thanks

73 de IK0MMI
andrea

Martin Smith
 

On Sat, Oct 26, 2019 at 02:36 PM, andrea ottaviani wrote:
I connected the orange server directly to the battery and the spikes are still there!
Even when running from battery modern processors can have requirements for multiple voltages 1.2v(CPU) ,1.5v(CPU) ,1.8v(DRAM/CPU) , 3.3v (I/O). One or more of those are typically generated by a buck converter (or even a boost converter), because they are extremely efficient. At the heart of a DC-to-DC steps down voltage buck converter is a switch turning on and off the voltage at tens of kilohertz to hundreds of kilohertz (pulse wave or even square wave) and then putting that output voltage through a low pass filter to minimise the ripple on the required final output voltage. So in effect you will get all the odd harmonics of the pulse/square wave frequency over the RF spectrum injected into any nearby antenna.

And modern battery packs can contain cheap DC-to-DC steps up voltage boost converters inside them to raise the output voltage of say a Lithium Ion battery from about 3.6 to 3.85 volts up to 5+ volts. And would similarly generate odd harmonics of the pulse/square wave frequency over the RF spectrum.