Hi Hans & Tom,
>
>> 1. Where do I find a light weight HV power supply and why are there no
>> switched power supplies for 2 -3 kV?
They are available but, verrrrrrrry pricey.
>
>You won't because a switched HV supply will cost more than the
>entire PA, and is more difficult to engineer.
>
The engineering is not that hard. Two chips can take care of most of
the work.
One for a PFC boost stage -- Micro Linear ML4812, Texas Instruments
(formerly Unitrode) UC1853/54, Linear Tech. LT1248/49
Another for a Phase Shift inverter control -- Micro Linear ML4818,
Texas Instruments (formerly Unitrode) UCC3895.
At the 500 watt level you can use the old (i.e. inexpensive)
International Rectifier, or Motorola (now ON Semiconductor) IRF450 FET
family or equivalents.
If you have some convenient chassis, to heat sink the FET's, then the
whole rest of the supply will only weigh a couple pounds (1 Kg).
The most troublesome individual task will be winding the transformer.
At this low power level there will have to be a large number of turns on
the core. It is much easier in the 2-3 KW neighborhood, where the
primary only requires about 20 turns; and the secondary 8 times that.
>It's especially difficult to switch thousands of volts in diodes, and
>keep RFI out of the receiving system. Of course, if you don't care
>about voltage regulation the supply gets easier to build.
Diodes are no problem, either. 1N6517 (5000V, 1A, 150nS, in a package
the size of a 1N5408!)
And if you keep the cross sections small (B*dL), RFI is not that hard
to control.
The phase shift controller IC's, mentioned above, provide voltage
regulation capabilities.
73,
Marv WC6W
*
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