[Amps] Fwd: Re: Lowering the voltage on a transformer

[Bill Fuqua]

>Date: Thu, 02 Aug 2012 11:37:51 -0400
>To: Peter Voelpel <df3kv at t-online.de>
>From: Bill Fuqua <wlfuqu00 at uky.edu>
>Subject: Re: [Amps] Lowering the voltage on a transformer
>
>Use a 25 volt buck transformer. It will about a quarter the size of full 
>rated one.
>Another possibility to go to a choke input filter. But either will add 
>weight and
>volume. However, you will get better load regulation and less power line drop
>if you use a choke input filter.
>   When you use a capacitive input filter all the current that charges the
>capacitor is drawn on the peaks. This is many times the current drawn
>from the power supply and when reflected to the primary it the peak current
>is many times the average and RMS. This produces flat tops on the sine wave
>on the input of the transformer and forces you to use much larger wire 
>from the
>breaker box to the amplifier than normally required for the same power into
>a non-reactive load.
>    An input choke smooths out this but in turn also reduces the output 
> voltage.
>73
>Bill wa4lav
>
>
>At 04:56 PM 8/2/2012 +0200, you wrote:
>>Just step it down on the primary with a 90V auto transformer before touching
>>the hv windings
>>
>>73
>>Peter, DJ7WW
>>
>>-----Original Message-----
>>From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
>>Behalf Of Peter
>>Sent: Donnerstag, 2. August 2012 16:48
>>To: amps at contesting.com
>>Subject: [Amps] Lowering the voltage on a transformer
>>
>>Hi
>>
>>I just get my hands on a nice transformer but the volttage is too high.
>>The transformer is rated 4000/4500V 3800VA I like to remove some secondary
>>windings to go to 2500-2600 V
>>
>>My question is:
>>Do I need equaly remove the windings on both sides?
>>1 side holds the "0"while the other side have the 4000/4500V tape
>>
>>I have some pictures at : http://www.pi4cc.nl/temp/hsp/
>>
>>Peter
>>PC2A
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