UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Improving Selectivity In Vintage Receivers

Jon_G4MDC · 30th Oct 2022, 3:49 pm

I have now added series resistors to L1 and L2 in the MUI statement as Q killers and now I have it in a tuned circuit which gives the same results as the 2.2mH Inductor with a Q of 100.

Looking at the the Top of the Coil 560k resistive at resonance.

Looking instead at the tap about 60k. This is much to high to load a ceramic filter correctly. I think I would probably just add a 2k resistor here instead or there will be lots of ripple in the response.

30th Oct 2022, 3:49 pm	#45
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: Improving Selectivity In Vintage Receivers I have now added series resistors to L1 and L2 in the MUI statement as Q killers and now I have it in a tuned circuit which gives the same results as the 2.2mH Inductor with a Q of 100. Looking at the the Top of the Coil 560k resistive at resonance. Looking instead at the tap about 60k. This is much to high to load a ceramic filter correctly. I think I would probably just add a 2k resistor here instead or there will be lots of ripple in the response.