[ARC5] Battery Report
Bill Cromwell
wrcromwell at gmail.com
Mon Feb 3 11:04:46 EST 2020
Hi Rich,
I found QRP transmitter project that uses a pair of the battery tubes
and could be powered by a series stack of 9-volt batteries. It will run
around about one watt and the batteries would not be hit very hard.
Those tubes are not capable of much higher power so the batteries loaf
along. A box full of xtals could cost far more than the transmitter! I
don't use the command transmitters here. I do like the receivers.
73,
Bill KU8H
On 2/3/20 12:14 AM, Rich Post wrote:
> 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
> <mailto: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>
> > <mailto: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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