[Amps] Direct rectification of AC mains to drive the amp,

[Jim Thomson]

##  Good point.   My yaesu  FT-1000D  sucks 1050 VA  from the wall plug, yet 
only puts
200w into a dummy load.   It only runs 50% PA eff too.   So 400 w dc input 
to get 200w output.
It doesn’t use a switcher either....just a huge torroid.

##  But sucking 1050 VA is plane nuts.  That implies a .2 PF.
Heck, any tube type kw linear amp is way better than that, typ with a .85 to 
.90 PF.

## Has anybody actually measured the PF on a transformerless supply, with a 
big C filter ???
I cant see it being any worse than your typ kw tube amp....with the typ xfmr 
+ FWB / Doubler +
high C filter.   Another option would be to use a transformerless supply + a 
choke input or
resonant choke input.

## Your typ commercial 1.5 kw CCS  SS  amp is huge $$ these days.  The 
switching supply is the
cheapest part.   $475.00  for a 3.3 kw CCS  switcher...... and unity/perfect 
PF to boot !   So the real savings
in any transformerless scheme is minimal at best......and NO PF correction 
either.    You could probably
series 2  or more  switchers in series for more VDD.

Jim   VE7RF





-----Original Message----- 
From: peter chadwick
Sent: Sunday, September 22, 2013 1:08 PM
To: Jim Thomson ; amps at contesting.com
Subject: RE: [Amps] Direct rectification of AC mains to drive the amp,

Jim,

What about power factor correction circuitry?

73

Peter G3RZP


========================================
Message Received: Sep 22 2013, 06:27 PM
From: "Jim Thomson" <jim.thom at telus.net>
To: amps at contesting.com
Cc:
Subject: [Amps]  Direct rectification of AC mains to drive the amp,

Date: Sat, 21 Sep 2013 09:50:52 -0700
From: Don Jones <ko7i at comcast.net>
To: amps at contesting.com
Subject: Re: [Amps] Direct rectification of AC mains to drive the amp,
VDD Supply

This is tricky. If the outlet you are using as the source is not daisy
chained to a bunch of other outlets and goes directly to the panel, and
you use a true 3 wire connection L1, L2 (or N) and Gnd, you can "get
away" with it provided you use an appropriately selected EMC filter too.
It is safe and efficient? no, heed the advice that you have been given
by others.
Vy 73, Don KO7i.

##  Why wouldn’t it be efficient ?    With direct rectification you just 
eliminated
the xfmr !   Now you have NO limit to the amount of power you can generate.
No V drop across any xfmr either, no sag...no xfmr.  Both static and dynamic 
regulation would be
better, a lot better.   No magnetizing current on the primary of the xfmr as 
there is no xfmr.
No heat generated from the xfmr...as there is NO xfmr.   You also just freed 
up a ton of
space.  You also eliminated  a ton of weight.

##  For high power use, Id say it’s the ideal ticket.   All you need is big 
ga  CU wire back to the
main 200A panel.   I would not write off a transformerless   supply just 
yet.    I think we are just getting
started.   240 x 1.414 =   340 vdc.......and  @  10-100A  CCS easily.

Jim  VE7RF
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