Test: ELAD FDM-S2 with the Intona USB 2.0 High Speed Isolator

These days I had the opportunity to test an Intona USB 2 high speed isolator on the SDR. Since I use the FDM-S2 at different locations, I decided for a disturbing reception area at home.

Unscreened USB cables were used for the first test setup. The antenna is the ALA 1530 S +. In Figs. 1 and 2 it can be seen that the intona increases the interference level in the medium wave range by an estimated 30 dBm. That was sufficient to put the galvanic isolator of the USB cable back into the original packaging.



Shielded USB cables were used days later. Here the isolator behaved as intended: it reduced the interference by 6-10 dBm. In my setup, a wound ferrite core was used, which was connected with and without an insulator. Fig. 3 shows the setup without isolator, Fig. 4 with isolator. The crackling noise level was not reduced but appeared as a chopped noise level on the screen and in the headphones. No faults were eliminated here, but an attempt was made to output them modulated differently.



The USB isolator behaves - without a measuring device - like a ferrite core for troubleshooting or like a standing wave barrier. For the proud price of 250 € you can buy 100 Amidon FT-140-43 ferrite cores. They are definitely a better alternative than the USB isolator from Intona.