The choke will improve the "static" regulation but will kill the dynamic
regulation.
Hook a scope up to the HV and run some CW with your key. You will see
negative spikes in the HV. Same on SSB.
73
Gary K4FMX
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
> On Behalf Of Carl
> Sent: Sunday, February 21, 2010 1:43 PM
> To: dezrat1242@yahoo.com; amps@contesting.com
> Subject: Re: [Amps] 120 Hz hum from Henry...
>
> A choke input filter with sufficient L or a swinging version will
> improve
> dynamic regulation over the typical commercial amps single C in any
> class of
> service. They were used for decades, and still are, in Class AB and B
> modulators.
>
> My 1200W LK-500 SSB/CW amp with 26uF filter has a 400-450V swing on the
> meter. My PP 304TL modulator with an untuned 20H choke input and 24uF of
> C
> has a 200V swing. The only purpose of choke tuning was to be able to use
> less inductance but there have always been reliability tradeoffs.
> Sometimes
> bigger is better.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Bill, W6WRT" <dezrat1242@yahoo.com>
> To: <amps@contesting.com>
> Sent: Sunday, February 21, 2010 12:57 PM
> Subject: Re: [Amps] 120 Hz hum from Henry...
>
>
> > ORIGINAL MESSAGE:
> >
> > On Sat, 20 Feb 2010 11:29:34 -0600, "Roy" <royanjoy@ncn.net> wrote:
> >
> >> Read the article,
> >>noting the careful tuning to exactly the 120 Hz resonant frequency:
> >>http://www.qsl.net/i0jx/supply.html
> >
> > REPLY:
> >
> > In that article, the author states:
> >
> > "There are however other approaches offering better regulation
> > performance (i.e. output voltage stability) at the expense of higher
> > complexity and cost; in particular the Input Choke Power Supply
> > (ICPS), in which a choke (L) is inserted between the diodes bridge and
> > the capacitor, as shown in Fig. 2."
> >
> >
> > That statement is true only in the case of a steady current draw (AM,
> > RTTY or FM). In the case of CW or SSB, a choke actually decreases the
> > dynamic regulation. A choke naturally opposes any change in DC current
> > flow through it and the result will be spikes in the voltage across
> > it, which are in turn applied across the capacitor and thus the
> > output. A large capacitor will absorb the spikes to some extent, but
> > can never eliminate them completely. A few minutes with a scope will
> > confirm this.
> >
> > When AM became obsolescent, so did the choke-input filter. For today's
> > amps a simple C-input is best.
> >
> > 73, Bill W6WRT
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
>
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