On Sun, Feb 16, 2025 at 07:46 AM, Donald Kirk wrote:
SFE10.7MA5-A
Don, attached are the specs I have for your filter. Note that the G.D.T. entry is blank. GDT means group delay time and this filter has no spec. Murata made many special types for FM IFs where group delay variation over the passband is specified. These filter types reduce detected audio distortion. The body of these filters is usually blue.
I've also attached the Murata test circuit. Note that the capacitor is specified on just one side of the filter. I assume its purpose is to account for the input capacitance of the stage the filter drives. Note that Murata specifies a tolerance of 2 pF for the 10 pF. I've attached curves that show response variation for various capacitive loads for a 230 kHz filter.
Brian
