I wouldnt use MOV's on the primary either, show me a reputable manufacturer
that does.
The problem with MOV's is they have a narrow current range where they are
most efficient and either side of that the internal resistance and heat goes
up. They also have a finite life.
Carl
KM1H
----- Original Message -----
From: "Hardy Landskov" <n7rt@cox.net>
To: "Manfred Mornhinweg" <manfred@ludens.cl>; <amps@contesting.com>
Sent: Saturday, September 14, 2013 3:39 PM
Subject: Re: [Amps] Rectifier equilization?
Hi All,
Well everyone is certainly getting the mileage out of my original post,
but I really want to thank everyone who responded. The concensus is just
go with the 5408's and everything should be fine. But use MOV's on the
primary and a good, HV bypass cap on the output as well as good 0.01's on
the power cord. And a step start of course.
73 Hardy N7RT
----- Original Message -----
From: "Manfred Mornhinweg" <manfred@ludens.cl>
To: <amps@contesting.com>
Sent: Saturday, September 14, 2013 12:14 PM
Subject: Re: [Amps] Rectifier equilization?
Bill,
FYI for next time, 6A10 diodes have become preferred by many for high
power
use because of their 6 amp continuous and 400 amp surge ratings and
moderate
cost.
I don't mean to say anything against 6A10 diodes, they sure work fine.
But they are HUGE overkill. Even if the filter capacitors had zero
equivalent series resistance, and the power outlet where the amp is
connected had zero impedance, and there were absolutely no inrush
limiting system used, and the power were switched on in just the worst
possible moment (peak of waveform), just the resistance of the HV
transformer will limit the current to roughly 20 to 30A, or maybe 40A if
the transformer is really beefy. And such a condition of course doesn't
happen in real life - specially the line from which the amplifier is
powered does have some resistance and also some inductance. In practical
use, in a normal home, it would be really rare to see more than 15A
inrush current.
1N5408 diode has a 200A surge rating, which is still big overkill. The
humble 1N4007 with its 30A surge rating would be about the right part to
choose for a cost-conscious builder! It's also comfortable with the
average current. Rated at 1 ampere average, a bridge rectifier using
strings of 1N4007 diodes is good for 2 amperes. That gives enough
headroom for a legal limit amp.
Feel free, of course, to use big diodes, if it gives you peace of mind.
But it shouldn't be technically necessary.
Jim,
## Both my 1N5408 and 6A10 diodes have identical lead diameters.
So do mine.
Both are I think, .050
Yes.
Manfred
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