UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Hallicrafters SX-43 FM drift.

Silicon · 23rd Oct 2020, 7:20 pm

The oscillator and mixer valves (a double triode) derive their HT from the reservoir capacitor.
There are then several R C stages to provide decoupling.

Have you ever monitored the HT voltage at C52 over the first hour after switch-on to see if it changes?

23rd Oct 2020, 7:20 pm	#10
Silicon Nonode Join Date: Jun 2007 Location: Coulsdon, London, UK. Posts: 2,163	Re: Hallicrafters SX-43 FM drift. The oscillator and mixer valves (a double triode) derive their HT from the reservoir capacitor. There are then several R C stages to provide decoupling. Have you ever monitored the HT voltage at C52 over the first hour after switch-on to see if it changes?