[Hammarlund] 6AH6 vs 6C4

[Carl]

.
>
> Again, yes. This last is one reason that National (and others) 
> incorporated
> filament current regulation (the 4H4C in the HRO-60) in the oscillator 
> circuits.
>
> The Collins R-390 and 390A are other examples.
>
> Anyway, I am going to do some experimentation.
>
> My goals are MINIMAL circuit and mechanical changes, coupled with greatly
> enhanced stability.
>
> As I have repeatedly stated, one of my basic principles is "KISS"...
>
> BTW, Electric Radio magazine recently published a very short article on a
> solid-state plug-in replacement for the 4H4C which almost exactly mimics
> that tube's characteristics, using an LM-317 in current regulator mode.

Why not a simple HW rectifier and a zener? Seems to work for me on any free 
running oscillator of which there are 3 in the HRO-60 and NC-183D. And then, 
since VR tubes are not really stable, use some more zeners.

Id also give the 6AH6 a try as a triode for G&G, it looks pretty impressive 
that way.

Im also a firm believer in KISS and not reinventing the wheel.

Carl
KM1H