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Re: [Amps] The power of an oversized electrolytic capacitor / how much P

To: amps@contesting.com
Subject: Re: [Amps] The power of an oversized electrolytic capacitor / how much PS filter C is enough?
From: Roger <sub1@rogerhalstead.com>
Date: Thu, 10 May 2012 23:19:15 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
On 5/10/2012 6:16 PM, Peter Voelpel wrote:
> Here we can use the three phases for any purpose we intend to.

As can we...IF it's available and it's pretty rare in residential areas. 
The nearest 3 phase line is about a mile away. Our entire feed is only 
48 KVA and I seriously doubt it'd handle that continuously.
Our standard household voltage is 120VAC single phase although we have 
240VAC available, not much except heavy duty appliances use it.
I have a milling machine with a 3 phase motor, so I had to add a rotary 
phase converter.  At the cost and installation of the converter, just to 
run the amplifier power supply would add a good $1000 - $1500 USD to the 
price of just the PS. Likely a bit more if you have to get a certified 
electrician to do the wiring.

figuring 764 watts per HP a 5 HP converter would only be good for 3,820 
watts at 100%.  @90% it'd only do 3438 watts.  a 1500 out amp at 60% 
efficient would take 2500 so "it should" be capable or powering a legal 
limit amp with a bit of overhead, but it sure wouldn't handle the legal 
limit class A. Oh! it also weights 116#

So, here it's not can we use it, but rather is it even available.

73

Roger (K8RI)

> Maximum power is 55KVA with my installation.
> In my HV power supply the 2µF capacitor is plenty, without it ripple voltage
> is 4%.
>
> 73
> Peter, DJ7WW
>
> -----Original Message-----
> From:amps-bounces@contesting.com  [mailto:amps-bounces@contesting.com] On
> Behalf Of Dr. David Kirkby
> Sent: Donnerstag, 10. Mai 2012 23:20
> To:amps@contesting.com
> Subject: Re: [Amps] The power of an oversized electrolytic capacitor / how
> much PS filter C is enough?
>
> On 05/10/12 12:19 PM, Leigh Turner wrote:
>
>> We can note the amplifier in question here uses a 4-1000 tetrode, and that
>> such tubes exhibit a plate current virtually independent of plate voltage,
>> i.e. tetrodes are a constant current device. Such a characteristic would
>> make it more immune to ripple and noise on the B+ plate supply.
>>
>> Leigh
>> VK5KLT
> More immune than what?
>
> Whilst the input current will be fairly independent of voltage, the input
> power,
> and hence output power will change if the HT supply varies. That leads to a
> loss
> of linearity.
>
>
> If you have the ability, then using a 3 phase transformer could be
> considered.
> Even without capacitors, the ripple is quite small, since unlike a single
> phase
> supply, the input voltage is never zero.
>
> I do have a 3 phase supply to my house, but it's not tempting to build an
> amp
> with it, as it restricts severely where you can use it.
>
>
>
> Dave
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