UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - 6-gang FM stereo tuner heads

G0HZU_JMR · 24th Jul 2022, 11:52 pm

I had a rummage today and managed to find a few 10.7MHz ceramic filters and measured a few on my VNA. The plot below is of the widest one I could find.

I took a full s2p model of the filter and then matched it using virtual components in a simulator. This method works extremely well when reproduced with real matching hardware. I think I can optimise the matching a bit more than this but see below for the first attempt to match the filter across about a 200kHz bandwidth. This filter isn't as wide as yours but it isn't far off. I can try and find a wider filter at work as there may still be some in a box under my desk.

24th Jul 2022, 11:52 pm	#139
G0HZU_JMR Dekatron Join Date: Sep 2010 Location: Cheltenham, Gloucestershire, UK. Posts: 3,077	Re: 6-gang FM stereo tuner heads I had a rummage today and managed to find a few 10.7MHz ceramic filters and measured a few on my VNA. The plot below is of the widest one I could find. I took a full s2p model of the filter and then matched it using virtual components in a simulator. This method works extremely well when reproduced with real matching hardware. I think I can optimise the matching a bit more than this but see below for the first attempt to match the filter across about a 200kHz bandwidth. This filter isn't as wide as yours but it isn't far off. I can try and find a wider filter at work as there may still be some in a box under my desk. Attached Thumbnails __________________ Regards, Jeremy G0HZU