Royce 1-642 Modulation Help Please

[nomadradio]

It's arithmetic. You cut a wire that feeds both the driver and final together. Bridge the cut with the current meter.

First turn both bias trimpots VR13 and VR14 for zero current. This is your starting point. Turn VR14 first, for 60 mA. Next turn VR13 so this reading increases to 100 mA.

That's what I would use, 60 mA for the final, and 40 mA for the driver. Since you can't isolate each and make a separate measurement, just use arithmetic to set the final first, then add the driver current to that reading.

73

 

[3pinplug]

Brilliant! Thank you ever so much i will have a go at the weekend and report back

 

[3pinplug]

Managed to try the procedure last night - very interesting!
I got 70ma across the cut wire link in the ammeter before touching anything, moving VR14 to zero took the 70ma to zero, so i put it back to 70ma with VR14 then turned VR13 ( which was set at halfway) to both ends of adjustment and it had no affect whatsoever on the 70ma value. Desoldered VR13 (1K) two leg vertical trimmer and tested in my Dvm and the trimmer is working fine from low up to 1K.
Wondering if dodgey durrounding component, dry joing or dodgey track.
Should i focus in these as maybe wrongly assumed VR13 would make a difference?