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

G0HZU_JMR · 26th Oct 2022, 9:26 pm

To show I've done this kind of thing before, see below for a cheapo SSB filter built using 9.83MHz crystals from RS that cost 25p each.

This was designed using a two-port model of the crystal and I let the computer optimise the ladder network for an SSB bandwidth. I then built it using the real crystals.

The plot below is taken of the real filter using the real crystals. There are 8 crystals in the filter and so it cost about £2 total for the crystals plus the cost of some ceramic SMD caps.

The plot below is across a 20kHz span. This isn't bad for a fairly decent SSB filter that cost maybe £3 using new parts.

26th Oct 2022, 9:26 pm	#18
G0HZU_JMR Dekatron Join Date: Sep 2010 Location: Cheltenham, Gloucestershire, UK. Posts: 3,077	Re: Improving Selectivity In Vintage Receivers To show I've done this kind of thing before, see below for a cheapo SSB filter built using 9.83MHz crystals from RS that cost 25p each. This was designed using a two-port model of the crystal and I let the computer optimise the ladder network for an SSB bandwidth. I then built it using the real crystals. The plot below is taken of the real filter using the real crystals. There are 8 crystals in the filter and so it cost about £2 total for the crystals plus the cost of some ceramic SMD caps. The plot below is across a 20kHz span. This isn't bad for a fairly decent SSB filter that cost maybe £3 using new parts. Attached Thumbnails __________________ Regards, Jeremy G0HZU