[snip]
>Skip, I can appreciate your concern about dirty lines but the DC end of
>the PS is not the place to start.
>I have been told by a PS designer that placing caps across a series
>string of diodes can lead to problems. The explanation was a bit over my
>head but I can put you in touch with the source if you wish....he is a
>highly placed and published PS designer for the military. It all has to
>do with the process used in manufacturing the diodes, which has changed
>over the years.
Yes and no Carl,
I don't consider it an exclusive DC portion of the power supply, although
I get your point.
Line filters are a wonderfull way to prevent problems, Mov's are nice
but don't save the day every time. A spike on the power line will pop
open or short an MOV, (I've seen both) and the next spike will take out
the circuit if the MOV opened. This is not exclusive circuit operation,
just some of the many horror stories I've seen close up. All dependant on
the design of the power supply of course. Properly done, a shorted MOV
would trip off a power supply, but some circuits need to "recycle" and
stay in operation, trying to prevent damage as possible.
Broadcast transmitters and Generation control circuits are a great example.
A lightning storm in the Sierra Nevada is an exciting place to "watch"
the grid from a generator control room.
The frequency responce of the Transformer plays an important role in my
designs. I measured the responce of a Heathkit SB-220 fillament
transformer years ago and found that it's design was especially good for
inrush current limiting and a relatively low Fc.
I'm not sure if the designers of the amp or the transformer planned it
that way, but the transformer prevented more than one problem "out of the
box". I do wish I knew who made the originals for Heath?
The point I'm trying to make is that High frequency components do make it
into the "DC" portion of a HV ps and that properly chosen bypass caps
would seem to prevent more problems than they would cause.
Please have your friend advise us why we might not want these capacitors
in circuit. I'm always open to other opinions and ideas.
thanks for your thoughts
73's
Skip May wv6f
mays@indigo.ucdavis.edu
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