Re: DC Filter Choke on low voltage power supplies

Posted by Steve Kercel on Feb 05, 2012; 7:11pm
URL: http://elecraft.85.s1.nabble.com/DC-Filter-Choke-on-low-voltage-power-supplies-tp7256286p7256445.html

Don and all:

Don is right, but I think that the situation is even worse than Don
describes. The power supply for a tube-type rig need only generate up to
a few Amps, not the 40 or 50 Amps that you might need for a big
solid-state rig. An inductor on the order of several Henrys and rated
for several tens of Amps would be impractically HUGE (and hideously
expensive) for table-top gear.

73,

Steve
AA4AK


On 2/5/2012 1:56 PM, Don Wilhelm wrote:

> Ed,
>
> Using a large filter choke in a relatively low voltage supply is
> difficult because of the voltage drop across the choke - and that
> voltage drop will change with current draw changes - so instead of
> improving the regulation, it will actually worsen.  The problem is in
> the size wire used to wind the choke.  In other words, a 25 volt drop at
> 3000 volts is a drop in the bucket, but even a 10 volt drop at 50 volts
> is likely to be too much.
>
> 73,
> Don W3FPR
>
> On 2/5/2012 12:54 PM, Edward R. Cole wrote:
>> Recent discussion of use of a filter choke with a battery powered K3
>> prompts my question in another application.  I have a 50vdc 50amp
>> switching PS which will power a 1100w sspa.  Output filtering may be
>> needed to suppress switching impulses on the 50vdc output.  I have a
>> large filter choke that was used in a 3000v PS which is probably at
>> least 5-8Hy.  Do I need a bleeder resistor across it for protecting
>> circuits when powering off the switching PS?  Or is using the large
>> filter choke not a good idea at all.  What size filter chokes would
>> be recommended?  The 50v PS is a HP PS intended for telephone industry (51v).
>>
>>
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