[Amps] Filtering capacitor in a HV PS: How low can you get away with?

[R.Measures]

On Aug 16, 2004, at 11:12 PM, Angel Vilaseca wrote:

> "R. Measures" wrote:
>>
>> On Aug 16, 2004, at 9:12 AM, Angel Vilaseca wrote:
>>
>>> Hi,
>>>
>>> I am building a 2500 V power supply for a one-KW transmitter. It will
>>> use 2 4CX20Bs.
>>>
>>> I have two oil-filled capacitors: 2.5 KV 40 uF  and a 4 KV 25 uF.
>>>
>>> I feel quite uncomfortable using the 40 uF 2.5 Kv one, because it 
>>> would
>>> work very close to its voltage limit.
>>>
>>> On the other hand, the 4 KV 25 uF would be OK as far as voltage is
>>> concerned, but would not 25 uF be too low?
>>>
>>> Is there a rule of thumb ?
>>
>> Angel -- Yes.  For a FWB, the filter C Å 50k / the R-load.   For a 
>> FWD,
>> each C Å 300k / R-load
>> cheerz
>
>
> So assuming amp resistance at max output is 3Kohms, we have 16 uF for a
> FWB and 100 uF for a FWD (?)
>
**  Yes, however, 2, 100uF capacitors in series are needed for FWD-  so 
the net C is 50uF.

> I am not sure what FWB and FWD mean.

**  FWB = full wave bridge rectifier, FWD = full wave (v)doubler.

> Is it inductance input filter and
> capacitor input filter?

**  C-only.
>
>
> Tnx fr your help

**  You are welcome, Angel.
>
>
>
Richard L. Measures, AG6K, 805.386.3734.  www.somis.org