[Amps] Power factor correction on tube amps

[amps at grebe.plus.com]

Hi Peter,

I had a feeling that the EU regs meant that any switching PSU over 100 W 
had to be power factor corrected.  Does this also apply to non switching 
PSUs such as in tube amps, Ameritron, Alpha etc. which are imported?  
The power factor of the average amp PSU with transformer, rectifier and 
reservoir cap is awful.  Am I missing something here?

73 John G3UUT

On 07/03/2013 10:05, peter chadwick wrote:
> Steve,
> How much filtering is there to meet EU regs on noise put on the mains, and is there any power factor correction circuitry?
> 73
> Peter G3RZP
>
>
>
>
>
> ========================================
> Message Received: Mar 07 2013, 08:50 AM
> From: "Steve Thompson"
> To: amps at contesting.com
> Cc:
> Subject: [Amps] Expert 1k amp
>
> Yesterday I did some minor repairs to a friend's amp - resoldering
> joints on the current sensing resistor. Looking at the circuits
> later I noticed that the main supply voltage is regulated by
> having SCRs in place of diodes rectifying the transformer
> secondary and the main smoothing capacitor is 47000uF.
>
> My friend tells me the amp runs over 40A at full tilt, which means
> something like 8.5V ripple on the supply (7V at 60Hz). That
> strikes me as quite high and I'd expect to see some difference in
> amplifier gain/output if I was running such an amp off a regulated
> supply and altered the voltage that much. Has anyone measured one?
> Is any 100/120Hz audible on a carrier?
>
> Steve
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