[ARC5] Converters for Q5-ers (PS hum)

[Roy Morgan]

On Jan 19, 2015, at 8:59 PM, Leslie Smith <vk2bcu at operamail.com> wrote:...
> 
> (4) The result is quite different when I use (modern) headphones.
> 
> The sound quality is quite good (except for the point below)
> considering the narrow I.F. (The I.F. 'slugs' are pushed 'in’.)

That means the IF bandwidth is widest it can be, right?

> DC filament supply v AC filament supply. Does AC to the filaments
> matter?

It might.  If you can find a set of 12 volt tubes and try them on battery filament power, it will tell you.

> B+ supply, from voltage doubler. 1/2 wave doubler, followed by x5 12V
> zeners in parallel with 470uF filter cap. (always thought 470uF would
> take out a lot of hum!)

The doubler may well be giving you some 50 cycle hum on the B+.  It would be 100 cycles with a full wave rectifier.
Try some more capacitance in parallel to see if it reduces the hum.

Roy

Roy Morgan
RoyMorgan at alum.mit.edu
K1LKY Since 1958