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

Radio Wrangler · 24th Nov 2022, 9:31 pm

It's a fractional-N frequency synthesiser. I'm not sure whether it's one of the analogue-phase-interpolation ones. Unless you are very comfortable with these things, I wouldn't recommend trying to repair at home.

I had the job of redesigning the API frac-N synth in the 3325A around a new LSI ASIC a number of years ago and while it's doable, getting all the spurs in-spec is a major undertaking. It may be that the 30MHz PLL is a straight forward one for the heterodyne band. The synth itself runs 30-51MHz and is mixed down to giv 0-21MHz

David

24th Nov 2022, 9:31 pm	#262
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,901	Re: 6-gang FM stereo tuner heads It's a fractional-N frequency synthesiser. I'm not sure whether it's one of the analogue-phase-interpolation ones. Unless you are very comfortable with these things, I wouldn't recommend trying to repair at home. I had the job of redesigning the API frac-N synth in the 3325A around a new LSI ASIC a number of years ago and while it's doable, getting all the spurs in-spec is a major undertaking. It may be that the 30MHz PLL is a straight forward one for the heterodyne band. The synth itself runs 30-51MHz and is mixed down to giv 0-21MHz David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done