Thats old news, a couple of caps takes care of that.
Carl
KM1H
> 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
>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|