[Elecraft] Battery power for the shack?

[George, W5YR]

John Clifford wrote:

> My questions:
> 
> 1) Do I need to protect my Alinco power supply by putting a large diode
> (Shottkey?) in the power lead from it to the radio buss?  I've heard that
> some power supplies can be damaged if they are off and there is voltage
> applied to their terminals.

Yes, you should isolate the power supply with a series diode and a suitable
fuse or breaker. In the absence of line power input, the battery would
otherwise place its voltage across the power supply output terminals and
could damage the series regulators, etc.

Similarly, it the power supply should crow-bar for any reason it would
otherwise short the battery; the diode prevents that and the fuse sweeps up
any remaining damage.
> 
> 2) Will the fuses in the two power strips be sufficient protection or should
> I put inline fuses between each battery and the battery buss, and between
> the two busses?

You need a fuse and diode between the supply and the battery and another
fuse between the battery and the radios, etc.
> 
> 3) Can anyone think of a better way to do this?

Looks good to me if you properly protect everything.
 
> 4) Has anyone ever taken a typical computer UPS, and added battery
> terminals/powerpole receptor to the back so that the internal gel-cell could
> be augmented by a much larger external battery?  That way I could run my
> large desktop computer/DSL modem during power outages, too.

That has been described in QST both as a means for bringing out the
internal battery leads to power equipment and to attach a larger battery
for extended UPS operation. But remember that your large computer and
monitor draw copious amperes. For example, if your computer has a 200 watt
power supply at 90% efficiency, it would require 250 watts at 120 volts or
over two amps. The monitor probably uses another 1.5 amps. So, the whole
computer system could draw 3 - 4 amps or so. You could get the better part
of a day's operation, especially if you turned off the monitor when not
actually using the computer.

One precaution: be aware of the output waveform of the UPS you use. Some
put out barely modified square waves which have high peak values while
others put out a reasonable sine wave. 

73/72/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
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