[amsat-bb] Re: Linear vs. switching and HV DC

Edward R. Cole kl7uw at acsalaska.net
Fri Feb 18 13:01:53 PST 2011

At 10:54 AM 2/18/2011, Bob Bruninga wrote:
> > Is there a Amsat BB favorite between switching and linear [power
>I won't speak to noise, which is the only potential issue with switching
>power supplies, but other than that, I am writing an article for QST that
>points out how the world of power and emergency power has changed
>drastically over the last decades.  Entirely due to switching power supplies
>and regulators:
>1) A 90% reduction in size and weight
>2) Laptop supplies that can supply 12v at 5 to 10 amps
>3) Universal inputs 115V to 240V AC
>4) * also run on 150 to 330 VDC
>5) Hybrids and Electric Vehicles have Kilowatts of 150 to 330 VDC available
>6) Home grid-tie solar has Kilowatts of high voltage DC available
>7) 12VDC to 120VAC inverters are now sine and modified sine at 90%+
>8) * These internally run on 200 VDC or so. Easy to run great distances on
>small wire if you run them directly on HV DC derived from your Hybrid or
>CONS: with today's litigious society and general ignorance (compared to the
>vacuum tube days when even cub-scouts built 2 tube radios with High
>Voltage), it is doubtful that QST will publish the article.  They have
>rejected it before, but I keep whittling away at the details.
>Bottom line, is that high efficiency high voltage DC is everywhere and
>because everything runs on switching power supplies that run internally on
>HV DC and regulators that accept a wide range of input, then HV DC could be
>the new universal power source.
>Problem is, Hybrid and EV MFR's are not going to provide access to HV DC
>willingly due to safety an liability issues.  Same for Solar installers....
>Same for QST.
>But you can get some of what I am writing about on this page:
>For example, buried in a Camry Hybrid is a nice compact stand-alone 14 volt
>100 AMP DC/DC supply.  Input can be 200 to 350 volts DC (which you can get
>from 120V or 240VAC with just some diodes)..  Problem is, it is bolted to
>the $1000 salvage battery and the salvage guys won't sell it separately.
>The Prius 100amp 14v supply is integrated into the huge drivetrain inverter
>and inseparable from that $3000 unit (salvage cost).
>As we electrify transportation and anyone with good sun goes solar, HV DC
>will be something Hams will be getting used to again.
>Bob, Wb4APR
>Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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I am rebuilding my 4.2kV PS for the 2m-8877.  Does that qualify?  QST 
still publishes high-power tube amplifier designs in their 
handbook.  What's 150-250v amongst friends?  Of course HV DC can 
badly burn or Kill you.

I was 14 years old when working on my DX-35 with 850vdc on the 6146 plate.

I agree that many hams these days aren't not trained to handle 
high-voltage with all the 12vdc solid-state electronics 
available.  But QRO sspa are running at 50vdc and higher.  There are 
rules for safe work on HV...time to review them.

73, Ed - KL7UW, WD2XSH/45
BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
EME: 144-1.4kw*, 432-100w, 1296-testing*, 3400-winter?
DUBUS Magazine USA Rep dubususa at hotmail.com
*temp not in service 

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