Positive is actually Negative and Negative is actually Positive.But
y'all don't expect the Society of Automobile Engineers to change their
books,do y'all? Those brits had it right all the time.I have to get my
beauty sleep now.Now I lay me down to sleep,I pray the Lord my soul to
keep,if I should die before I wake,I pray the Lord my soul to take.
Move over,Blueberry doggy.
cuhulin

wrote:

Cheap inverters put out square waves (not quite, but good enough for
this discussion). They make a ton of racket, so I can't see how anyone
would consider them suitable for use around radios. Further, if your
radio runs off of 12VDC, why take a 12V battery, invert it to 117V AC,
then step it down and rectify to 12VDC.

For devices that run off of 12V, note that the 12V is nominal. Just
about everything can run from the 13.8V float voltage, with margin. The
only pain in the arse is the Wellbrook pre-amp, which is positive
ground. Touch the case to to a negative ground and you pop the internal
fuse. When I use the device in the field, I place it in a zip lock bag,
poking a hole for the cable. They really should have insulated the
thing. Of couse, you need to build a special postive ground cable
(cigarette lighter adapter) and make sure you only use it with the
wellbrook.

In the future, I'm going to build a 12V distribution box using cannon
connectors. Those cigarette lighter connectors are really crap.


I use Exeltech inverters for things that won't run directly off 12 or
24 volts, and they are quite clean unless run at or above rated
capacity (Their ratings are quite conservative). Exeltechs are pure
sine wave inverters -- they are very good, and cost more than your
typical Big Box inverters.

As for distribution, I use West Mountain Radio RigRunners with
Anderson PowerPole connectors. These are used by ARES, are rated to
30 amps in 12VDC and are "genderless" in that any connector can
connect to any other.

http://www.exeltech.com
http://www.westmountainradio.com

wrote:
On 29 Oct 2005 20:24:26 -0700, "junius" wrote:

Hi Joe...

I'm curious, do you find that the inverter generates noise, as
suggests it would?

I'm not Joe however I have use radios in the vicinity of [inexpensive]
inverters and have found them to be very effective noise generators.

Joe Analssandrini wrote:
Dear Bruce,

I own a Century Electri-pac Model BPIP-99 (Portable Electric Power -
Cordless and Rechargeable) which meets all your requirements. I bought
it several years ago from THE SPORTSMAN'S GUIDE catalog ($75.00 at the
time). I do not know if this model is still available, but you could
investigate. Similar items are available at THE PEP BOYS.

In fact I have powered my AOR AR7030 Plus and my Wellbrook ALA 330S
from this unit. Everything worked fine.

Best,

Joe

--
Eric F. Richards,
"Nature abhors a vacuum tube." -- J. R. Pierce, Bell Labs, c. 1940

OK,get two six volt electric Golf Cart batteries and hook them up with a
couple of battery cables to get twelve volts.
cuhulin

Hello Junius,

The unit probably would generate noise if one placed it near the radio.
But why would anyone do that? ANY eectrical generator will generate RFI
if a radio is placed close to it. SOMETIMES one has to use common
sense! (That's why they invented extension cords.)

Best,

Joe

The so-called sine wave coming out of the inverter will be full of
harmonics. The extension cord could make things worse since it would
radiate these harmonics. Again, why go from 12VDC to 117VAC and then
back to 12VDC? If you really insist on going the inverter route, look
for the buzzwords "pure sine" and get the lowest harmonic distortion
unit you can find.

Still, I'm baffled why anyone would use an inverter. You have gone from
perfection (a battery) to a less than clean power.



Joe Analssandrini wrote:
Hello Junius,

The unit probably would generate noise if one placed it near the radio.
But why would anyone do that? ANY eectrical generator will generate RFI
if a radio is placed close to it. SOMETIMES one has to use common
sense! (That's why they invented extension cords.)

Best,

Joe

In article . com,
bpnjensen wrote:
Hi, folks - I would like to try running my Icom R-75 at home from a 12
- 13.8 volt cell or battery. The requirements would be that the cell
would be able to recharge from 115v AC during the radio's off time, and
that while the radio is turned on, the battery would be electrically
disconnected from the wall AC. It does not matter to me whether this
connect / disconnect is manual or automatic.

My cure for the power outage blues was to go buy a "Jump Start Power Pack"
in the automotive section of the local Target store. This is a 19 Amp
Hour Gel cell in a plastic case with a built in volt meter and jumper
cables, and a "cigarette lighter" power jack on the front. It uses a
seperate wall wart for the charger. It was on sale at about half the
one off catalog price of a similar sized gel battery. $35, as I remember.

They're a standard item in automotive stores and big box discount
stores. Some even have built in 120 volt AC "inverters" built in.
Vector, Coleman (the camping equipment people), and many others
"make" them. (Well, import them from China).

The power hasn't gone out since, but I've used it to start the car
several times.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)

1% distortion quoted above by Eric is a very nice number. Both types
of inverters square and sine can cause problems with noise. Do not
confuse high frequency switching noise with lower frequency harmonic
distortion that you would get with square waves. They are not the
same. Noise can come from many different sources within the inverter.

Inverter usually has a small switcher running to generate logic
supplies, fan voltages, and other various houskeeping chores.
Inverter may also have microprocessor dsp, or a simple microcontroller
that runs on MHz clock
Inverter may actually have an intermediate inverter switching at 100kHz
or more to get the low level dc up to a higher dc level compatable with
your AC mains voltage.
Finally the actual output sine or square wave is generated by switching
a big mosfet or IGBT that has very steep edges. 5,000 - 10,000v/us is
a reasonable dv/dt to expect. All of these noise sources will
contribute to the overall problem.

Various techniques are used with inverters in order to mitigate both
radiated and conducted EMI. Proper grounding, routing of wires,
sheilding, and finally filtering are all tools of the trade. Best bet
is to try and minimis=ze it at the source.

For the casual user best bet may be to start with a manufacturer that
others have recommended. Exeltech? LC filters to clean up the output
will help. Can set the filter to just above 60Hz and should do nice
job. WWW.CWSBYTEMARK.COM might be a good source for toroidal powder
iron filter cores.Series traps (directly across the output) might be a
good approach if the noise spectrum is known. Mounting the inverter in
another box could help. Mounting the inverter in a remote area and
using a longer extension cord could help. Wrapping the extension cord
around a Hi Mu core where it enters the shack might help as well.

I design large high performance inverters for a living, but I try to
buy gear that will run off of 12v.

Regards,
Bob

www.devilfinder.com Submarine Batteries
cuhulin

Get a big old Submarine battery.You will need a forklift to move that
Submarine battery around though.My old buddy collects old Railroad
thingys and he has a few of those old timey heavy glass jar Railroad
batteries sitting behind his garage.
cuhulin