Several people in this group have noted that they run their receivers
off of sla batteries. I'm curious: did you notice much of a reduction
in noise?

Steve

There are (at least) two different types of slas.
GellCells, and regular lead acid batteries that
are sealed.
I have only used the GellCell variety.
It is hard to get a AC mains powered supply really quite.
You can reduce maybe 99% of the noise.
Most of the time that is enough. Givent he local and worldwide
noise 99% is below the noise floor most of us deal with.
For me the biggest advantage to using a gellcell is for
emergencies. When the lights go out I an keep listening.
I have a Lamda 12V rated at 8Amp, but will deliver about 14A
before going into current limiting, power supply that I bought for
$10.00 from a local surplus dealer. Big ugly and heavy.
No meters and a barrior strip for the AC mains 120V and the
12V out. It was already wuite, but I added some more noise
suppression. A Coreman heavy duty double stage IEC female
power connector to help keep it's noise from getting back into the
AC mains. I bypassed all 8 of the bridge diodes with 0.001uF
mylar to help prevent IM via the diodes. I added several ferrite
cores to the +12V out. I drilled a lot of additonal holes to add
1 connector (more or less) to the case halves for better RFI
"containment". I added a 120V 60HZ relay to open the PS +DC
output and a connector for my gellcell, a 24A/Hr panasonic unit.
I replaced the single turn voltage adjust pot with a10 turn unit
that Imounted onthe case. I keep it adjusted to +13.69V, the
suggested "float" volatage for gellcells.
It has worked great for several years now.
I power all of my 12V equipment from this single supply.
The main advantage being that it is much quiter then the
built in supplis on my radio and scanners, and I only
had to cleanup one supply instead of five.
Does it make a dffference, yes. My shack is much quiter,
that is has much less RF noise and I can connect any of the five
receivers/scanners to 120 and use the built in supply and
the noise floor jumps over 10dB.
I have also added the best ground I can afford. Used double shielded
coax for all my receiving antennas and connected all my equipment
with 1/2" tinned braid to a single grounding point.

Terry

99% would mean you are left with 1 part in a hundred, or 20db
reduction. I don't think it would make that much difference. At least,
I never heard that much of a noise reduction.

I think everyone should have the means to run their rigs from an
automobile, so instead of running out to buy a SLA , rig up a cigarete
lighter interface for your radio. Run the radio from your car (engine
NOT running) and see if you can hear the difference. Now that you can
listen on your rig mobile, drive out to the middle of nowhere and
compare the noise (assuming you don't already live in the middle of
nowhere). I've found locally generated noise to be a bigger problem
than my AC, though my radio uses a soap on a rope style power supply.

Once you have run your radio from the auto battery, if you think iti
makes a difference, buy the gell cell. I pull two 12V 7AH Yuasa from my
gate every other year just to be sure the thing doesn't fail when I
don't have time to fix it. I use the old SLAs for radio power supplies,
but only when camping. I notice no difference at the house.

If you really want less noise, get a Wellbrook loop. An added advantage
is you no longer need a ground since the Wellbrook floats. I use the
ALA 100 and a homemade loop. Mine is also set up to run from 12V,
though you need to note that the power to the Wellbrook is positive
ground. If you build your own cigarette lighter adapter, this is not a
big deal, just make sure you label it so you don't blow up gear
expecting negative ground.

wrote:
99% would mean you are left with 1 part in a hundred, or 20db
reduction. I don't think it would make that much difference. At
least,
I never heard that much of a noise reduction.

I think everyone should have the means to run their rigs from an
automobile, so instead of running out to buy a SLA , rig up a
cigarete
lighter interface for your radio. Run the radio from your car (engine
NOT running) and see if you can hear the difference. Now that you can
listen on your rig mobile, drive out to the middle of nowhere and
compare the noise (assuming you don't already live in the middle of
nowhere). I've found locally generated noise to be a bigger problem
than my AC, though my radio uses a soap on a rope style power supply.

Once you have run your radio from the auto battery, if you think iti
makes a difference, buy the gell cell. I pull two 12V 7AH Yuasa from
my
gate every other year just to be sure the thing doesn't fail when I
don't have time to fix it. I use the old SLAs for radio power
supplies,
but only when camping. I notice no difference at the house.

If you really want less noise, get a Wellbrook loop. An added
advantage
is you no longer need a ground since the Wellbrook floats. I use the
ALA 100 and a homemade loop. Mine is also set up to run from 12V,
though you need to note that the power to the Wellbrook is positive
ground. If you build your own cigarette lighter adapter, this is not
a
big deal, just make sure you label it so you don't blow up gear
expecting negative ground.

I actually use one of the Wellbrook loops, and they do help a lot with
noise reduction. However, as I learned when I attached ferrite cores to
a lot of the cables in my house, it's the noise you don't notice that
can get you. I had no idea ferrite cores would make a significant
difference in my noise level, but they did. Now I'm wondering if there
are other things I can do to bring the noise level down even lower,
like operate from a gel cell or regular sla battery.

Steve

A "dead" car battery, even though it can't provide enough current to
start a car, can provide enough current to run a radio for a long, long
time before it really does die.

One of the big questions is will the diodes in a radio power supply
cause cross modulation. It doesn't happen all that often,
but when it does it is a nightmare. I prefferred to take my time and
do one supply right. I actually have 2, it is nice to have a spare,
just in case. On the R2000's and my Pro2004, the internal supply
always adds a little frying noise. Most of the time the residual
"background" noise swamps that minor noise.
But on nights when the band is quite, that little bit of noise is very
frustrating. I have used salvaged ferrite cores on the power, audio,
video, and RF cables going to EVERY piece of equipment
in our house. I took a bunch of GE MOVs, the kind that plug into the
AC outlet and have a female socket, added a 0.1uF cap between
both "hot" and "nuetral" to ground, and found it to help quiten the
house way down. While the nuetral and ground are connected in the
breaker box, it did help a great deal to quite the TV, alarm clock,
and microwave down. The microwave is still nasty, but my wife doesn't
like it or use it that much. I was goong to add them to the duplex
outlets
but the local electrical inspector nixed that idea. Getting all three
PCs,
my wifes, mine and the dedicated MP3 "juke box" PC, was the biggest
heartache. I had to put multiple ferrite cores on every cable that had
anything
to do with the PCs.
For my car Iused an unused power tap in the main fuse box, and routed
the wire through the firewall to a Cannon style 4pin female XLR. That
type
connector is often found on commercial TV field gear, so I decided to
standardise so I can hook my 12V devices up to the supplies at work.
I used a "bunch" of ferrite cores in a failed attempt to quiten my 1991
Civic.
It is much better then it was before, but it is still way to noisy to
even think
about adding a SW to use while driving. Thank God for MP3 players. I
get
to choose what music I listen to, with no DJs, ads or idiots.

Terry

A lot of folks don't know it,but Positive really is Negative and
Negative really is Positive.The Brits had it right all along.But is the
Society of Automobile Engineers (or whatever it is called) going to
change their books? I don't think so!
cuhulin

What I need to do is take out the street lights!

Since you have a Wellbrook, build the cables and do the car battery
trick. You will probably need one of those cigarette lighter boxes
that increase the number of outlets.

Be sure to check out the cables for shorts. I really don't like those
coaxial connectors. You need to use heat shrink to make sure nothing
shorts. What I do is get junk wall warts just for the cable and coaxial
power connector, then solder the cigarette lighter connector. The
cigarette lighter connectors are pretty foolproof.

Ferrite is good stuff, but one noise source are those cat5 cables which
I beleive you can't use a ferrite without degrading the network. I know
they sell shielded cat5, but I wonder if the extra capacitance will
cause network problems.

The canon connectors sounds like a good idea. There are quite compact
and very secure, i.e .the plug doesn't fall out.

It seems to me the MOVs provide protection, but I don't see why they
would limit noise UNLESS they are preventing spikes from shooting
through your power supply. Moto has a family of diodes used for
snubbing spikes. These go on the DC path.

Read what www.pricewheeler.com www.brickwall.com says about MOVs.I
use a Brickwall model PW8R15 lightning strike/surge filter.
cuhulin