UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Another "Pantry" Rig for the IC-allergic

Ian - G4JQT · 18th Jul 2019, 10:40 am

That's a nice circuit mictester. The VFO buffer should give isolation and the regulator IC should also add to frequency stability.

I'd be minded to make the LPF components variable so that optimum output is reached with whatever (short!) antenna is used.

In my experience even linear wall-wart PSUs need plenty of RF decoupling: X-cap across the mains, and 22nF-ish across the secondary, the diodes and output voltage terminals to minimise modulation hum when received on some nearby mains receivers.

The SMPU wall-warts are a nightmare on many levels and best avoided - not that anyone is suggesting them.

Thanks for sharing the design.

Ian

18th Jul 2019, 10:40 am	#16
Ian - G4JQT Octode Join Date: Jun 2004 Location: Reading/Fakenham, UK. Posts: 1,326	Re: Another "Pantry" Rig for the IC-allergic That's a nice circuit mictester. The VFO buffer should give isolation and the regulator IC should also add to frequency stability. I'd be minded to make the LPF components variable so that optimum output is reached with whatever (short!) antenna is used. In my experience even linear wall-wart PSUs need plenty of RF decoupling: X-cap across the mains, and 22nF-ish across the secondary, the diodes and output voltage terminals to minimise modulation hum when received on some nearby mains receivers. The SMPU wall-warts are a nightmare on many levels and best avoided - not that anyone is suggesting them. Thanks for sharing the design. Ian