[ARC5] Battery Report

Mon Feb 3 00:14:08 EST 2020

Hi Bill,

At only 15 mA, those batteries would indeed last quite sometime.  I've used
that same solution for Zenith Transoceanics.

I built a power supply for QRP for command sets using "impoverished
experimenter" parts, recycled from a couple of small UPS.  One UPS re-uses
its power transformer but the second donated its power transformer to the
battery compartment of the first making essentially a poor man's isolation
transformer package.  That combination was then also used to provide the B+
for a QRP command transmitter. The low voltage from the first transformer
was used for the filament supply.  Was part of an article in the January
2016 issue of *THE SPECTRUM MONITOR*. (Also showed a QRO supply and results
from using them on the air)

That same "Impoverished Experimenter" supply could easily power a Command
receiver.
I've placed a picture and couple of schematics from the article here.  In
order to continue using the supply occasionally for its original isolation
purpose, I did not connect the B- to the case, but when used to power the
command set, I clip an extra external wire from the command set chassis
back to the power supply case.
<https://people.ohio.edu/postr/bapix/command.htm>

73 de Rich KB8TAD

On Sun, Feb 2, 2020 at 10:44 PM Bill Cromwell <wrcromwell at gmail.com> wrote:

> Hi Rich,
>
> I started using the batteries for B+ to avoid power line crud conducted
> into the radio from that source. Digital (switched mode) power supplies
> are usually pretty noisy too. It worked and the noise pollution into the
> radios was reduced. As a side benefit my radios didn't turn off when the
> electric grid went down:) I use 7.5 A-H sealed lead-acid batteries For
> the heater strings. So throw away batteries for B+ that lasts weeks or
> months and bigger ones for the heaters that can be recharged over and
> over - is that redundant?
>
> I settled on 90 volts and the radios draw about 15 mA at 90 volts B+. I
> also tried 45 volts. The radios worked and the radios only drew about 7
> or 8 mA but performance was down enough to notice. I could change those
> screen bias resistors and use just 45 volts but I am reluctant to
> further modify those radios. They haven't been hacked to bits but do
> have some reversible mods that were installed long before I acquired them.
>
> 73,
>
> Bill  KU8H
>
> On 2/2/20 4:23 PM, Rich Post wrote:
> > I have also found that the cheap old fashioned carbon zinc cells seem to
> > be less prone to leakage than alkaline cells.  Like Wayne, I use the
> > cheap Sunbeam cells from Dollar Tree.  If I am concerned about leakage,
> > I place several soldered together inside a pill bottle and run leads to
> > the outside with wire nuts.  That is especially useful in VOMs where the
> > original "D" cell holder is broken or  damaged by leakage products.  The
> > pill bottle size is chosen to fit the "D" cell space and the wire nuts
> > make it easy to replace the package later.
> >
> > For powering a Command set receiver, I have yet to try a simple tripler
> > or quadrupler off the 24 volt transformer used for filaments. Have
> > successfully used such a tripler for 90 volts of B+ to a farm set.
> > Given the relatively limited current draw, a quadrupler might work for a
> > Command receiver.
> >
> > Rich KB8TAD
> >
> > On Sun, Feb 2, 2020 at 3:39 PM Robert Eleazer <releazer at earthlink.net
> > <mailto:releazer at earthlink.net>> wrote:
> >
> >     __
> >     It seems to me that the old carbon zinc cells (which I believe the
> >     Sunbeam cells from Dollar Tree represent) were less likely to leak
> >     than the modern alkalines.  I think they did less damage, tooi.
> >     Remember when Everyready advertised leak proof cells and that they
> >     would replace the flashlight if required?  I think they stopped that
> >     when the alkalines came out.
> >     As for as rechargable cells, the LI-Ion types seem to be far
> >     superior to nicads and NIMH when it comes to holding a charge.  I do
> >     have a couple of 18657 Li-Ion cells that arrived brand new and dead
> >     with no re-charging and a couple more that died after a short
> >     service life.
> >
> >     Wayne
> >     WB5WSV
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> --
> bark less - wag more
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