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Old January 25th 05, 04:22 PM
 
Posts: n/a
Default 12 v or 13.8?

When looking for a power supply for my Alinco dr-590, what type of
power supply would I look for? The radio says 13.8 v dc but if I get a
12 volt power supply will it put out the same wattage at the radio?

  #2   Report Post  
Old January 25th 05, 05:55 PM
Richard Clark
 
Posts: n/a
Default

On 25 Jan 2005 08:22:59 -0800, wrote:

When looking for a power supply for my Alinco dr-590, what type of
power supply would I look for? The radio says 13.8 v dc but if I get a
12 volt power supply will it put out the same wattage at the radio?


Hi Don,

Do the math. You have the same load - less voltage. The power laws
describe this simply as EČ/R.

However, it is very, very, very unlikely that you have 12.0 V of
anything as this is a "nominal" voltage, and almost never an actual
voltage. The 12 V label is derived from the common application of the
Lead-Acid Edison Battery. The cells of this battery develop 2.1 V
potential, and with their common combination into batteries of either
3 cells or 6 cells, those bring the total up to 6.3 V or 12.6 V. Many
here will recognize these values as common filament voltages for
tubes. So even here, common transformers that are either 6 or 12 V
specified, actually supply more voltage under load (because they were
originally filament power transformers).

The specification for 13.8 V is derived from the automotive electrical
system that was designed (with its voltage regulator and
generator/alternator) to supply a "float" voltage that would keep the
battery topped off while simultaneously carrying the load. Hence,
mobile applications are designed for this configuration and the source
should be robust enough to support the load.

Now, it seems to me you were using a deep discharge battery, or you
were planning to do so. This is a common application in the shack, I
have two batteries in parallel held up with a 20A trickle charge
(voltage adjusted to the optimum value). The charger (actually a
precision source from Acopian) is not large enough to supply my HF
rigs under full power out (my Drake TR-7 is rated well above 100W) but
the combination of batteries and charger manage quite well. Also, I
have connectored everything so that I can strip down, transport and
reconfigure for field day operations (sans charger).

73's
Richard Clark, KB7QHC
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Old January 25th 05, 07:12 PM
 
Posts: n/a
Default


Richard Clark wrote:
On 25 Jan 2005 08:22:59 -0800, wrote:

When looking for a power supply for my Alinco dr-590, what type of
power supply would I look for? The radio says 13.8 v dc but if I get

a
12 volt power supply will it put out the same wattage at the radio?


Hi Don,

Do the math. You have the same load - less voltage. The power laws
describe this simply as E=B2/R.

However, it is very, very, very unlikely that you have 12.0 V of
anything as this is a "nominal" voltage, and almost never an actual
voltage. The 12 V label is derived from the common application of

the
Lead-Acid Edison Battery. The cells of this battery develop 2.1 V
potential, and with their common combination into batteries of either
3 cells or 6 cells, those bring the total up to 6.3 V or 12.6 V.

Many
here will recognize these values as common filament voltages for
tubes. So even here, common transformers that are either 6 or 12 V
specified, actually supply more voltage under load (because they were
originally filament power transformers).

The specification for 13.8 V is derived from the automotive

electrical
system that was designed (with its voltage regulator and
generator/alternator) to supply a "float" voltage that would keep the
battery topped off while simultaneously carrying the load. Hence,
mobile applications are designed for this configuration and the

source
should be robust enough to support the load.

Now, it seems to me you were using a deep discharge battery, or you
were planning to do so. This is a common application in the shack, I
have two batteries in parallel held up with a 20A trickle charge
(voltage adjusted to the optimum value). The charger (actually a
precision source from Acopian) is not large enough to supply my HF
rigs under full power out (my Drake TR-7 is rated well above 100W)

but
the combination of batteries and charger manage quite well. Also, I
have connectored everything so that I can strip down, transport and
reconfigure for field day operations (sans charger).

73's
Richard Clark, KB7QHC


So you are saying it wont matter?

I was wanting to use the marine battery I have but someone else posted
a negative experience with the fumes ruining part of their house and
their own health. It scared me a little.

I was looking at power supplies on ebay and some of them stated 12
volts (older ones) some said 13.8. That is why I asked.
I am still a little confused on what way I need to go.

  #4   Report Post  
Old January 25th 05, 07:31 PM
Jim Kelley
 
Posts: n/a
Default



wrote:

Richard Clark wrote:

On 25 Jan 2005 08:22:59 -0800,
wrote:


When looking for a power supply for my Alinco dr-590, what type of
power supply would I look for? The radio says 13.8 v dc but if I get


a

12 volt power supply will it put out the same wattage at the radio?


Hi Don,

Do the math. You have the same load - less voltage. The power laws
describe this simply as EČ/R.

However, it is very, very, very unlikely that you have 12.0 V of
anything as this is a "nominal" voltage, and almost never an actual
voltage. The 12 V label is derived from the common application of


the

Lead-Acid Edison Battery. The cells of this battery develop 2.1 V
potential, and with their common combination into batteries of either
3 cells or 6 cells, those bring the total up to 6.3 V or 12.6 V.


Many

here will recognize these values as common filament voltages for
tubes. So even here, common transformers that are either 6 or 12 V
specified, actually supply more voltage under load (because they were
originally filament power transformers).

The specification for 13.8 V is derived from the automotive


electrical

system that was designed (with its voltage regulator and
generator/alternator) to supply a "float" voltage that would keep the
battery topped off while simultaneously carrying the load. Hence,
mobile applications are designed for this configuration and the


source

should be robust enough to support the load.

Now, it seems to me you were using a deep discharge battery, or you
were planning to do so. This is a common application in the shack, I
have two batteries in parallel held up with a 20A trickle charge
(voltage adjusted to the optimum value). The charger (actually a
precision source from Acopian) is not large enough to supply my HF
rigs under full power out (my Drake TR-7 is rated well above 100W)


but

the combination of batteries and charger manage quite well. Also, I
have connectored everything so that I can strip down, transport and
reconfigure for field day operations (sans charger).

73's
Richard Clark, KB7QHC



So you are saying it wont matter?

I was wanting to use the marine battery I have but someone else posted
a negative experience with the fumes ruining part of their house and
their own health. It scared me a little.

I was looking at power supplies on ebay and some of them stated 12
volts (older ones) some said 13.8. That is why I asked.
I am still a little confused on what way I need to go.


Richard always writes as if he's entering a prose contest. He has some
difficulty communicating with Earthlings. :-)

ac6xg

  #5   Report Post  
Old January 25th 05, 08:27 PM
H. Adam Stevens, NQ5H
 
Posts: n/a
Default


"Jim Kelley" wrote in message
...
snip
Richard always writes as if he's entering a prose contest. He has some
difficulty communicating with Earthlings. :-)

ac6xg

Jim
That's 'cause he gets his plonk from Reg.
;^))))
73
H.




  #6   Report Post  
Old January 26th 05, 12:35 AM
Topaz305RK
 
Posts: n/a
Default

Jim -

How politically correct!

In the military it is called "Getting $12,000 worth of education shoved
up your rear end a nickel at a time".



  #7   Report Post  
Old January 25th 05, 09:15 PM
Tam/WB2TT
 
Posts: n/a
Default


wrote in message
oups.com...

Richard Clark wrote:
On 25 Jan 2005 08:22:59 -0800, wrote:

When looking for a power supply for my Alinco dr-590, what type of
power supply would I look for? The radio says 13.8 v dc but if I get

a
12 volt power supply will it put out the same wattage at the radio?


Hi Don,

Do the math. You have the same load - less voltage. The power laws
describe this simply as EČ/R.

However, it is very, very, very unlikely that you have 12.0 V of
anything as this is a "nominal" voltage, and almost never an actual
voltage. The 12 V label is derived from the common application of

the
Lead-Acid Edison Battery. The cells of this battery develop 2.1 V
potential, and with their common combination into batteries of either
3 cells or 6 cells, those bring the total up to 6.3 V or 12.6 V.

Many
here will recognize these values as common filament voltages for
tubes. So even here, common transformers that are either 6 or 12 V
specified, actually supply more voltage under load (because they were
originally filament power transformers).

The specification for 13.8 V is derived from the automotive

electrical
system that was designed (with its voltage regulator and
generator/alternator) to supply a "float" voltage that would keep the
battery topped off while simultaneously carrying the load. Hence,
mobile applications are designed for this configuration and the

source
should be robust enough to support the load.

Now, it seems to me you were using a deep discharge battery, or you
were planning to do so. This is a common application in the shack, I
have two batteries in parallel held up with a 20A trickle charge
(voltage adjusted to the optimum value). The charger (actually a
precision source from Acopian) is not large enough to supply my HF
rigs under full power out (my Drake TR-7 is rated well above 100W)

but
the combination of batteries and charger manage quite well. Also, I
have connectored everything so that I can strip down, transport and
reconfigure for field day operations (sans charger).

73's
Richard Clark, KB7QHC


So you are saying it wont matter?

I was wanting to use the marine battery I have but someone else posted
a negative experience with the fumes ruining part of their house and
their own health. It scared me a little.

I was looking at power supplies on ebay and some of them stated 12
volts (older ones) some said 13.8. That is why I asked.
I am still a little confused on what way I need to go.

As far as I know, 100% of supplies sold for ham use are 13.8V, or
thereabouts. 12 Volts was a standard voltage for many linear ICs, along with
15 V. My Astron switching supply came set for 14.05 V. I don't see that as a
problem because all my stuff can be used in a car, and I have never seen the
car voltage drop below 14 V with the engine running.

Tam/WB2TT


  #8   Report Post  
Old January 25th 05, 09:32 PM
H. Adam Stevens, NQ5H
 
Posts: n/a
Default


"Tam/WB2TT" wrote in message
...

wrote in message
oups.com...

Richard Clark wrote:
On 25 Jan 2005 08:22:59 -0800, wrote:

When looking for a power supply for my Alinco dr-590, what type of
power supply would I look for? The radio says 13.8 v dc but if I get

a
12 volt power supply will it put out the same wattage at the radio?


Hi Don,

Do the math. You have the same load - less voltage. The power laws
describe this simply as EČ/R.

However, it is very, very, very unlikely that you have 12.0 V of
anything as this is a "nominal" voltage, and almost never an actual
voltage. The 12 V label is derived from the common application of

the
Lead-Acid Edison Battery. The cells of this battery develop 2.1 V
potential, and with their common combination into batteries of either
3 cells or 6 cells, those bring the total up to 6.3 V or 12.6 V.

Many
here will recognize these values as common filament voltages for
tubes. So even here, common transformers that are either 6 or 12 V
specified, actually supply more voltage under load (because they were
originally filament power transformers).

The specification for 13.8 V is derived from the automotive

electrical
system that was designed (with its voltage regulator and
generator/alternator) to supply a "float" voltage that would keep the
battery topped off while simultaneously carrying the load. Hence,
mobile applications are designed for this configuration and the

source
should be robust enough to support the load.

Now, it seems to me you were using a deep discharge battery, or you
were planning to do so. This is a common application in the shack, I
have two batteries in parallel held up with a 20A trickle charge
(voltage adjusted to the optimum value). The charger (actually a
precision source from Acopian) is not large enough to supply my HF
rigs under full power out (my Drake TR-7 is rated well above 100W)

but
the combination of batteries and charger manage quite well. Also, I
have connectored everything so that I can strip down, transport and
reconfigure for field day operations (sans charger).

73's
Richard Clark, KB7QHC


So you are saying it wont matter?

I was wanting to use the marine battery I have but someone else posted
a negative experience with the fumes ruining part of their house and
their own health. It scared me a little.

I was looking at power supplies on ebay and some of them stated 12
volts (older ones) some said 13.8. That is why I asked.
I am still a little confused on what way I need to go.

As far as I know, 100% of supplies sold for ham use are 13.8V, or
thereabouts. 12 Volts was a standard voltage for many linear ICs, along
with 15 V. My Astron switching supply came set for 14.05 V. I don't see
that as a problem because all my stuff can be used in a car, and I have
never seen the car voltage drop below 14 V with the engine running.

Tam/WB2TT

Bingo
Try Sealed Lead Acid batteries, BTW.
73
H.


  #9   Report Post  
Old January 26th 05, 02:18 PM
Cecil Moore
 
Posts: n/a
Default

"Tam/WB2TT" wrote in message
...
I was wanting to use the marine battery I have but someone else posted
a negative experience with the fumes ruining part of their house and
their own health. It scared me a little.


I have a marine battery charged by an Astron RS-20M and a 75w solar panel.
I monitor the battery voltage and shut off the charging system when the
battery
is charged. That decreases the possibility of battery failure.
--
73, Cecil http://www.qsl.net/w5dxp




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  #10   Report Post  
Old January 25th 05, 09:32 PM
Jack Painter
 
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wrote
I was wanting to use the marine battery I have but someone else posted
a negative experience with the fumes ruining part of their house and
their own health. It scared me a little.

Starting with a new battery, I have used a 12v marine deep-cell with small
float-charger to power a 25w VHF transceiver for over two years. For short
periods, this will handle 100w xmit on an HF rig that draws 20-30amp. When a
charger is connected to a battery, adequate ventilation must be provided,
and the smoking lamp is "out". There is nothing wrong with using an
emergency backup battery as part of normal (indoor) operations. It will
provide hundreds of hours of monitoring and several minutes of low-power
transmit w/o requiring a charge.

Jack Painter
Virginia Beach, Virginia




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