[Amps] Capacitors vs No Capacitors

Larry Benko xxw0qe at comcast.net
Thu Apr 19 16:36:20 PDT 2012


Dan,

I don't quite calculate the same number.

If the source is 3 phase power and halfwave rectification the ripple 
would be 50%.  This is most likely _not_ the case.  In the more likely 
case of full wave rectification and 3 phase power the ripple would be 
13.4%.  In the halfwave case there is always one phase within +/-60 
degrees of the max. (1 - sin(30 deg.) = 0.5) and in the fullwave case 
there is always one phase within +/-30 degrees of the max. (1 - sin(60 
deg.) = .866).  This of course is the ideal case and additional voltage 
drops in the transformer, wiring, etc. would increase the ripple.

73,
Larry, W0QE

On 4/19/2012 3:47 PM, Dan Mills wrote:
> On Wed, 2012-04-18 at 18:15 -0500, donroden at hiwaay.net wrote:
>> Thinking out loud.....
>>
>> A 15KV @ 10 mf in a Broadcast FM transmitter many years ago shorted...........
>> No noticable hum on carrier  ( yes, I know .... FM )
>> AM noise above FCC specs ??  Probably, but they were back on the air.
> If the rig was big enough to operate on three phase power then there
> would only have been about 30% ripple even without a cap in there, so I
> am not at all surprised that an FM TX would work without a cap.
>
> 73s, Dan.
>
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