Yes again on your comments below Jim. I use a commercial Taiwanese MeanWell
3.3 kW PF corrected switcher for my 8 x VRF2933 HF S.S. amplifier. It's a
very compact unit and runs cool and is EMI / EMC quiet with no discernable
emissions. The unit meets all EU directives and international conformance
regulations.
However as Manfred points out in respect of simple rectifier-capacitor input
power supplies most practical transformers significantly improve the PF
situation compared to direct AC mains connection due to the xfmr's leakage
inductance and finite winding resistance.
Leigh
VK5KLT
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Jim Thomson
Sent: Sunday, 29 September 2013 8:14 AM
To: amps@contesting.com
Subject: [Amps] ?Direct rectification of AC mains to drive the
++snip++
>
>Yes all that you mention below is correct Jim. That's why I commented in an
>earlier post that an individual QRO amp builder would get away with doing
>this questionable 3 kW power supply realization technique, but no
>commercial SS amp manufacture would be able to do this due to the
>electrical codes in respect of EU power factor rules and product compliance
>certification.
REPLY:
Power factor correction is an area I am a bit hazy on. Could someone explain
why the power factor would be different between a direct-rectified PS and a
transformer-isolated one? Either one charges the capacitors with a series of
pulses. What's the difference in power factor?
73, Bill W6WRT
## There is NO difference in PF between direct rectified and a xfmr! It's
virtually impossible to try and implement PF correction with either
scheme...esp with ssb-cw PF is typ .85 to .90 with a high C filter..with or
without Xfmr.
## PF correction is done all the time with the newer style switching
supplies. Then you end up with unity PF at all phase angles. The typ
switcher will also operate on anything from 170-325 vac on its input....and
from 40-70 hz. Telcos and cell sites have switched over en masse to the
new style switchers. 3.3 kw each in the typ 52 vdc @ 63A unit....with 6 in
a 25 inch wide rack. They are only aprx 7 inch tall X 14 inch deep. with a
huge load on em, they are not even luke warm. We literally brought in
truck loads of em 2-3 years ago. Zero failures...and they are on 24-7-365.
At $475.00 each.... they are a bargain for what you get.
Apparently they can also be strung in series, but I have not verified this.
## Still, I would not get wound up about PF correction with any ham gear...
nor V regulation
Jim VE7RF
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