>From: Steve Katz <stevek@jmr.com>
>To: 'Rich' <2@vc.net>, Alan Ibbetson <g3xaq@hotmail.com>, AMPS
><amps@contesting.com>
>
>I don't believe a 1 kg power supply using a 6x multiplier at 50 Hz or 60 Hz
>is possible, at the current level required
>
> > From: Rich [SMTP:2@vc.net]
> > The lightest weight power supply would likely be a voltage-multiplier
> > type operating direct from the electric mains. With a x6 V multiplier
> > and 230V mains, c. 1600vdc could be produced for c, 1kg in ps weight.
Although Steve doesn't believe it, a Pspice simulation suggests that a 6X
multiplier using "just enough" 470uF 385v capacitors to keep within their
voltage rating (15 in all) and 240v/50Hz mains gives 2KV off load and 1.45KV
with 200v p-p ripple at 500mA load. Capacitor ripple current is a tad under
3A rms. Peak mains current is 11A, and yes these are horrid spikes so don't
tell the power company! My box of 15 caps weighs 750 gr, so Rich's weight
estimate seems about right too.
The "nice" way to do it is with a high voltage SMPS. Harry/W3IIT referred me
to QEX Feb 1991 for a nice simple design, thanks. The down side of this
example is that it does not attempt to be RFI proof. The author shuts off
the switcher during receive. This is OK if you are single-op, but is
unsuitable for multi-multi.
Dave/G4FRE ( robinda@nortelnetworks.com ) in a private email outlined his
successful use of MOSFETs
>I now use the motorola 2 x mrf154 amp for expeditions capable of 800W
>2-50MHz, the main weight of which is the >copper spreader/heatsink. I used
>to use the 4 x mrf150 but that got retired as it did not cover 6m
Please Dave: I think it would be of general interest to hear the details of
how the EB104 application note was turned into a fully functioning multiband
amp.
Thanks to everyone who took the trouble to follow up to my original posting.
73,
Alan G3XAQ
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