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Denoising the mains power supply.
Use a cheap mains noise filter or
an expensive ultra isolation transformer ?
pa0nhc 20180325 / 20180404 / 20191222


800 - 1500 Euro.
Ultra isolation transformer.


18 / 31 Euro.
Schaffner FN2060 10A / 16 A 
multistage mains noise filter.
More than 50 dB suppression of  
common mode noises and
differntial mode noises.


Schaffner FN2060-10
250V~10A filter : 18 Euro
  B = common mode.
A/C/D = differential mode


Schaffner FN2060-16
250V~16A filter : 31 Euro
B=common mode.
A/C/D = differential mode

 


Schema of these multistage filters
<= To radios          From mains power <= 
** noise-free RF ground => "PE" **

Important : 
The filter should be connected in reverse.
" P' " and " N' " should be connected as an INPUT from the mains power.
" P "  and " N " should be connected as an OUTPUT, to the radio equipment.
Ground connection "PE"  should be connected to a separate noise free ground.
 The mains related yellow-green safety ground wire should NOT be connected.
Recommended :
The supplying power line should contain an automatic leak current switch,
which protects against accidental touching live wires.

Switched Mode Power Supplies and other equipment often inject RF noises into the mains power supply network. These noises will partly be radiated, and partly be conducted towards your radio room. In receiving equipment they can cause annoying noises and signals. One way to reduce the interference is blocking the net related noises as soon they reach your house or radio room.

An "Ultra Isolation Transformer"  separates the power network for RF from the shack. Thanks to its special construction, it has a very low coupling capacitance between primary and secondary windings. RF coupling is further damped by its iron core. But it is expensive. Before buying such a transformer, a test with a good and relative cheap mains filter could be done. 

The here presented filters have more than 50 dB suppression of common mode noises AND differential mode noises in the frequency range between 400 kHz and 30 MHz, which is of interest for radio amateurs. REM : Mouser.com has these filters in stock.

When using such a filter, a separate noisefree RF ground is needed.
RF ground made with water pressure.