Jim Isbell wrote:
After collecting parts for most of a year I am in the serious design
stage of a 4-1000A linear. The power supply, because of its size is to
be external and connected by a cable.
In the first design I was going to bring the 6500VDC power through a
cable to the linear. But then it occurred to me that since the main
reason for the separate supply was the size...which is MOSTLY the 12KVA
transformer I am using. It might be safer to just make the transformer
external and have the rectifiers and filter capacitors in the
transmitter case thus allowing the only the transmission of AC, at a
lower potential, (using a voltage doubler circuit) in the cable. Thus,
by just turning off the input power I could eliminate the potential on
the cable instantly...or almost so...while the filter capacitors which
are the biggest danger would be in the transmitter cage and would be
connected to shorting circuits controlled by the safety switches on the
lid of the transmitter.
There must be some reason this is not a good idea as I have never seen
it done.
It's mostly the inconvenience of running several high-voltage,
high-current cables - and also multiple redundant safety ground bonding.
You also need to think *very* carefully about the right locations for
mains and HV-AC fuses, to protect against a short if any wire breaks...
or any pair of wires... or...
In all other respects, it's not much different from 'remoting' the
complete HV power supply, and that's a routine thing to do.
--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
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