RF Technical Blog of World Family of Radio Maria

I ended now to test the possibility  to measure the Return Loss of a coaxial filter with some simple tools , like an RTL Key , a Noise Generator and a SWR Bridge , a software and a laptop . I have used the following setup :  And two different software :  A) HDSDR ( that we already have used in three video for pointing satellites , measuring the satellite Beacons and check and measure in the FM band ) :  https://www.hdsdr.de/ B) SATSAGEN from Alberto Ferraris :  https://www.albfer.com/satsagen-download-page/ The results are in the following pictures :  HDSDR : Much faster , but easy to saturate , limited span and limited markers possibilities SATSAGEN  : Much slower , but difficult to saturate , no limited in higher span , big facilities on markers  At the end , at these frequencies and for these amplitude ranges , with SOME PATIENCE AND SKILLS, the results are quite "similar" to that of a professional HP instrument as follow :  Of course...

How to tune a Coaxial Filter     In Fig.1 is shown the connection between Spectrum Analyzer-Rhotector (VSWR Bridge ) and a Coaxial Filter:                                                             Fig. 1. Connections between the instruments.   With this kind of connection you can measure the Return Loss or the Standing Wave Ratio of the coaxial filter at port F (shown in Fig. 1), Table 1 reports the relationship between the R.L and the VSWR. Table 1. Return Loss and SWR.     The Coaxial Filter is tuned by rotating the four knobs named Lin, Lacc1, Lacc2 and Lout, as in Fig 2. Delta Meccanica provides a graduation and a table for  the first position where is better to start the tuning. Fig. 2. Tuning Kobs. Delta Meccanica provides a graduation and a table for  the first position...