[Boatanchors] Choke Info Needed

[mac]

On Oct 9, 2009, at 6:59 AM, Carl wrote:

> Low C was only before higher values became readily available/ 
> affordable and pretty much confined to pre WW2.

Yes, of course, but we were talking tradition.......

> In a modulator with a 5-25H or higher swinger input and 40+ uF  
> output C the ripple is not audible.

Obviously.

> This assumes that the driver stages are well filtered to eliminate  
> the GIGO effect. Minimum bleeder current is needed to keep the HV  
> from soaring and once the modulator tubes are on they provide the  
> remaining bleeder stabilzation.

And all a swinging choke really does is allow the use of a higher  
resistance, lower wattage bleeder resistor in those cases where the  
load current will fall below a critical value during normal operation,  
CW  being the classic situation.

> The resultant HV variation in a Class B modulator is better than  
> most SSB linears.
>
> In an AM only RF amp many do away with the choke and use a lot of C  
> when a low impedance transformer is used. However when using old  
> high impedance iron a choke input is recommended with SS rectifiers  
> and mandatory with 866's. I use only SS in all the power supplies  
> and a mix of transformers and filter schemes.

My original query to Mark was why a swinging choke? Subsequently  
learned he was building up a PS for an ART-13.  Swinging choke nice to  
use on a choke input filter if you can find one but not mandatory as  
many appear to believe.  I use a 10H, 300ma "smoothing" type in the PS  
for my ATC.

Dennis D. W7QHO
Glendale, CA