From: email@here.invalid   
      
   On 03/09/2025 14:20, Cursitor Doom wrote:   
   > Gentlemen,   
   >   
   > I have an early AVO valve tester (twin panel type, Mk1 or Mk2) which   
   > I'm trying to get fully working. Anyway, I have a problem with it   
   > which I've never encountered before. I set the panels up to test a   
   > valve, set the anode and heater voltages etc, the valves are glowing   
   > just like they should, but when I apply the prods of a DVM across the   
   > heater pins to check if they're correct WRT the switch setting, that   
   > tiny extra load completely collapses the supply to the heaters! The   
   > meter reads 0V (or close enough) and the heater glow dims to nothing.   
   > Any idea WTF's going on here?   
      
   If the circuit has any sort of gain, are you creating a feedback path   
   with noise radiating cables that oscillates and overwhelms the power   
   delivery of the supply? Try the meter switched to AC, or an   
   oscilloscope, you may still see something.   
      
   --   
   Adrian C   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)