More Volts Input = More RF Watts Output?
ko4qc
T6766 wrote:
>
> Hi,
>
> I have a Cobra 18RV Mobile CB radio. I have tried several DC power
> supplies
> (including Radio Shack and Uniden types) and I think I have come to a good
> conclusion. When I use a 9 Volt power adopter, the S/TX meter only goes
> up to about three (3) LEDs. When I use a 12 Volt adopter, it goes to four
> (4) LEDS. And finally when I use a tunable power supply that goes from
> 3-17 Volts, I find that the more Volts input I give, the more LEDs light
> up, which seems to mean that more RF power is being radiated from the
> unit. So I now run it on about 16 Volts,
> but the radio needs only 13.8 Volts, and it seems to work best with about
> 16 volts. If anyone can confirm or deny this theary, please post it here.
>
> Thanks,
> Eugene
I f I were you I would plug it directly into 220-240 volts.Wont even
need a 'leeneer' then!!!
T6766
Carlos Pulido
In <19970329031...@ladder01.news.aol.com> t6...@aol.com
Eugene,
Transistors love voltage, just don't over do it !!!
A lot of folks run their rigs at 16 volts,, Not only will you see a
slight increase in transmit performance but you will without doubt see
a hotter receiver as well, especially on SSB..
Understand however that the components inside your rig have voltage
ratings, particularly the caps, and by exceeding the working voltage
you will destruct them.. There are also resistor biasing networks that
set up the correct operating points for the transistors and if you
increase the voltage to them you will also increase the heat or
operating wattage that they are rated for; the I.C.'s fall under this
same catagory since it is the heat that they cannot dissipate due to
the increased voltage...
Keep in mind that while you will reap some benefits, the hotter
receiver in particular, you will also be shortening your rigs overall
life expectancy and if there was something on the way out,
the 16 volts will surely help you find out what it was..
In other words run the 16, do it conciously, and if there comes the
moment when something goes, don't take it as a surprise..
Just enjoy it till it does or till it never does... !!!!
P.S. I run all my radios at 15.0 volts.....
(your 16 is 1 volt too high for my sanity)
Dan K Nelson
T6766 wrote:
>
> Hi,
>
> I have a Cobra 18RV Mobile CB radio. I have tried several DC power supplies
> (including Radio Shack and Uniden types) and I think I have come to a good
> conclusion. When I use a 9 Volt power adopter, the S/TX meter only goes
> up to about three (3) LEDs. When I use a 12 Volt adopter, it goes to four
> (4) LEDS. And finally when I use a tunable power supply that goes from
> 3-17 Volts, I find that the more Volts input I give, the more LEDs light
> up, which seems to mean that more RF power is being radiated from the
> unit. So I now run it on about 16 Volts,
> but the radio needs only 13.8 Volts, and it seems to work best with about
> 16 volts. If anyone can confirm or deny this theary, please post it here.
>
> Thanks,
> Eugene
Eugene,
A simple application of Ohm's law applied to your question will validate your
theory... (hint - what is the result of voltage multiplied by current, and what
is it's unit of measure?)
73's,
<<< DAN >>>
--
+-------------------------------------------------------+
|An Armed Man is a Citizen, an Unarmed Man is a Subject.|
+-------------------------------------------------------+
cod...@aol.com
Greetings!
In article <19970329031...@ladder01.news.aol.com>, t6...@aol.com (T6766) writes:
>So I now run it on about 16 Volts,
>but the radio needs only 13.8 Volts, and it seems to work best with about
>16 volts. If anyone can confirm or deny this theary, please post it here.
Nor can we deny...
You're taking chances running the radio with that high of a voltage constantly.
As said in an earlier post - there are voltage sensitive components that are
put there in an effort to reduce manufacturing costs and yet be still well within
limits of a typical automotive electrical system - and not cause a fire or
a blown radio.
The radio you're using needs good regulation - but can operate at a slightly
higher voltage. There are other voltage sensitive areas that can tolerate
higher power supply voltages - but if their maximum level is exceeded -
you'll find your room filled with "Magic Smoke", a burned out radio, and
it's power supply too - along with a startled, then pissed - operator.
"Slightly" is left open for interpetation here...;-)
"pissed" too... ;-?
Yes, you will produce more wattage, and more heat - you can't have one
without the other in this type of situation - operating your radio like that.
There are other things that you'll also find out - not only with the aforementioned
postings, but other less noticable things that experience will teach you.
I'll also admit I've had my share of fun/sad/experiences like this too -
Just look at the Carbonized, Charred-Chassis, carcasses laying around
my shack performing assorted duty offices like paperweights and mementos.
Someday, you'll collect enough debri to understand...
Once you've started smoking...it's hard to quit - OH! The Smell! ;-)
ROTFL!!!
Yes, it is a slow news day...Happy Easter!
~~~One final note from the Litter Box:~~~
ATTENTION COMMERCIAL E-MAILERS!:
Please REMOVE this address from your
list - you're wasting your time!
- Thank You.
Wizard
T6766 wrote:
>
> Hi,
>
> I have a Cobra 18RV Mobile CB radio. I have tried several DC power
> supplies
> (including Radio Shack and Uniden types) and I think I have come to a good
> conclusion. When I use a 9 Volt power adopter, the S/TX meter only goes
> up to about three (3) LEDs. When I use a 12 Volt adopter, it goes to four
> (4) LEDS. And finally when I use a tunable power supply that goes from
> 3-17 Volts, I find that the more Volts input I give, the more LEDs light
> up, which seems to mean that more RF power is being radiated from the
> but the radio needs only 13.8 Volts, and it seems to work best with about
> 16 volts. If anyone can confirm or deny this theary, please post it here.
>
> Eugene
Eugene,
Even though you feed the radio with 16 volts that does not mean your
getting more power out..The internal regulators are just being taxed to
there max..They are desinged to bring 13.8 volts down to 12 & 5 volts
which is what most of the circuts use..In a nut shell your heading
toward premature failure of the radio..Go to Radio Shack and buy a 12
volt power supply,make sure its the regulated one..Match the antenna to
the radio and you will get all the radio has to offer..
Best of Luck
The Wizard (Rick)
RADIOGOD
Dan K Nelson wrote:
>
> T6766 wrote:
> >
> > Hi,
> >
> > I have a Cobra 18RV Mobile CB radio. I have tried several DC power supplies
> > (including Radio Shack and Uniden types) and I think I have come to a good
> > conclusion. When I use a 9 Volt power adopter, the S/TX meter only goes
> > up to about three (3) LEDs. When I use a 12 Volt adopter, it goes to four
> > (4) LEDS. And finally when I use a tunable power supply that goes from
> > 3-17 Volts, I find that the more Volts input I give, the more LEDs light
> > up, which seems to mean that more RF power is being radiated from the
> > unit. So I now run it on about 16 Volts,
> > but the radio needs only 13.8 Volts, and it seems to work best with about
> > 16 volts. If anyone can confirm or deny this theary, please post it here.
> >
> > Thanks,
> > Eugene
>
> Eugene,
>
> theory... (hint - what is the result of voltage multiplied by current, and what
> is it's unit of measure?)
>
> 73's,
>
> <<< DAN >>>
>
> --
> +-------------------------------------------------------+
> |An Armed Man is a Citizen, an Unarmed Man is a Subject.|
> +-------------------------------------------------------+
Here's the deal, Bucky. The engineers designed your radio (and all
other CB's too) to operate at a DC input voltage of 13.8. There is a
small amount of variation acceptable either higher or lower. You will
get more power out of the radio with a higher voltage applied, but it
will result in a fried radio in a short time. You make the call.
Nobody will ever notice the difference in your signal, is it worth it?
Michael volz
ko4qc wrote:
>
> T6766 wrote:
> >
> > Hi,
> >
> > I have a Cobra 18RV Mobile CB radio. I have tried several DC power
> > supplies
> > (including Radio Shack and Uniden types) and I think I have come to a good
> > conclusion. When I use a 9 Volt power adopter, the S/TX meter only goes
> > up to about three (3) LEDs. When I use a 12 Volt adopter, it goes to four
> > (4) LEDS. And finally when I use a tunable power supply that goes from
> > 3-17 Volts, I find that the more Volts input I give, the more LEDs light
> > up, which seems to mean that more RF power is being radiated from the
> > unit. So I now run it on about 16 Volts,
> > but the radio needs only 13.8 Volts, and it seems to work best with about
> > 16 volts. If anyone can confirm or deny this theary, please post it here.
> >
> > Thanks,
> > Eugene
> need a 'leeneer' then!!!
Boy, real constructive. What if he did hook into 220? Post mortem
regrets.
The radio will, to a point perform better with more voltage. How long
it will keep working is another thing (until it breaks from too much
voltage) :-). It will put out more at more than 13.8; but you don't
really want to run it there as it will shorten the life of the radio,
possibly considerably shorten. Run it at 12-14, 15 if you absolutely
have to.
Yes, in a car, the voltage can be 14.8-15 or a little more, but why
operate the radio out of design parameters when you don't have to?
In conclusion, just keep it as close to 13.8 as is reasonably possible.
But you may get some hum with your transmitted signal since that power
adapter may not be able to give enough current. :)
73,
Mike
ko4qc
If he had a 'clue' as to power amplification theory,he would realize
the minimal amount of power gained through an additional 2-4 volts will
not make a detectable difference!If you arent increasing your output by
100%,you are wasting your time.
In other words,'he wont get any more DBs outta it'!
Andy Moss
Wizard wrote:
>
> T6766 wrote:
> >
> > Hi,
> >
> > I have a Cobra 18RV Mobile CB radio. I have tried several DC power
> > supplies
> > (including Radio Shack and Uniden types) and I think I have come to a good
> > conclusion. When I use a 9 Volt power adopter, the S/TX meter only goes
> > up to about three (3) LEDs. When I use a 12 Volt adopter, it goes to four
> > (4) LEDS. And finally when I use a tunable power supply that goes from
> > 3-17 Volts, I find that the more Volts input I give, the more LEDs light
> > up, which seems to mean that more RF power is being radiated from the
> > unit. So I now run it on about 16 Volts,
> > but the radio needs only 13.8 Volts, and it seems to work best with about
> > 16 volts. If anyone can confirm or deny this theary, please post it here.
> >
> > Thanks,
> > Eugene
>
> Even though you feed the radio with 16 volts that does not mean your
> getting more power out..The internal regulators are just being taxed to
> there max..They are desinged to bring 13.8 volts down to 12 & 5 volts
> which is what most of the circuts use..In a nut shell your heading
> toward premature failure of the radio..Go to Radio Shack and buy a 12
> volt power supply,make sure its the regulated one..Match the antenna to
> the radio and you will get all the radio has to offer..
I've never seen a CB radio that regulated the voltage supply to the
final transistor!
Wait, I vaguely recall that the old Radio Shack TRC448 had a
configuration like that. However, it had trouble putting out 12Watt PEP
on SSB.
More input voltage will invariably give you more power. It will also
incur other problems too, though. Expensive problems! !
Cheers!
--
Andy Moss
"In God we trust - the rest can pay cash......."
Steve Eklund
Be careful when using voltage over about 15 volts. Many products are
protected from over volatge by using a 16 volt zener diode across the
incoming power line. When voltage exceeds 16 volts, the zener diode will
begin to clamp down and draw excessive current through the fuse.
Hopefully the fuse will blow at this point and everything will be OK,
but I have seen cases where the zener diode pops too. Not a big deal
because you can simply remove it and defeat the protection that it
offers, but you are better off keeping your power supply no higher than
16 volts to avoid such problems to begin with.
73 from Steve
the...@aol.com
I tested many of my radios in an attempt to find the optimum voltage
to power ratio. The units failed most often when above 16 volts. I would
recommend you maintain the standard 13.8 - 14 volts on base units. Mobile
operation at 16 volts, two 8 volt lead-acid batteries in series, are often used
by the so-called high powered operators with good luck.
I believe the voltage drop in the power cables used keeps the voltage
levels lower at perhaps 14 volts. Really those units are safe 'cause the voltage
keeps droppin' as they keep talkin'.
Carl
The2x4
Chris Lypchuk
On Sat, 29 Mar 1997, Wizard wrote:
> T6766 wrote:
> >
> > Hi,
> >
> > I have a Cobra 18RV Mobile CB radio. I have tried several DC power
> > supplies
> > (including Radio Shack and Uniden types) and I think I have come to a good
> > conclusion. When I use a 9 Volt power adopter, the S/TX meter only goes
> > up to about three (3) LEDs. When I use a 12 Volt adopter, it goes to four
> > (4) LEDS. And finally when I use a tunable power supply that goes from
> > 3-17 Volts, I find that the more Volts input I give, the more LEDs light
> > up, which seems to mean that more RF power is being radiated from the
> > unit. So I now run it on about 16 Volts,
> > but the radio needs only 13.8 Volts, and it seems to work best with about
> > 16 volts. If anyone can confirm or deny this theary, please post it here.
> >
> > Thanks,
>
>
I've tried cranking up the DC power on my radio too, it does work
a little with radios that have no power (or poor ) regulation in them. I
know that for sure because I checked my radiated power with a field
strenght meter. At about 16 volts the radio worked well, even seemed to
give better audio quality as well as more RF output.
CHRASH
Sara or Mike Bratcher
ko4qc wrote:
>
> T6766 wrote:
> >
> > Hi,
> >
> > I have a Cobra 18RV Mobile CB radio. I have tried several DC power
> > supplies
> > (including Radio Shack and Uniden types) and I think I have come to a good
> > conclusion. When I use a 9 Volt power adopter, the S/TX meter only goes
> > up to about three (3) LEDs. When I use a 12 Volt adopter, it goes to four
> > (4) LEDS. And finally when I use a tunable power supply that goes from
> > 3-17 Volts, I find that the more Volts input I give, the more LEDs light
> > up, which seems to mean that more RF power is being radiated from the
> > unit. So I now run it on about 16 Volts,
> > but the radio needs only 13.8 Volts, and it seems to work best with about
> > 16 volts. If anyone can confirm or deny this theary, please post it here.
> >
> > Thanks,
> I f I were you I would plug it directly into 220-240 volts.Wont even
> need a 'leeneer' then!!!
hello-
Can I use the cord of a old heater. Does it make any diferance what
wire goes to the hot side. thanks Mike
Michael volz
Sara or Mike Bratcher wrote:
>
> ko4qc wrote:
> >
> > T6766 wrote:
> > >
> > I f I were you I would plug it directly into 220-240 volts.Wont even
> > need a 'leeneer' then!!!
>
> hello-
>
> Can I use the cord of a old heater. Does it make any diferance what
> wire goes to the hot side. thanks Mike
You DO NOT EVER want to plug in a 12 Volt radio into the wall with a
cord. Meaning putting 120 Volts into a radio designed for 12 volt input
unless you want:
1. Your radio to be immedieately fried.
2. Yourself possibly killed or injured.
Thanks Joel for the initial idea of directly plugging it in in the first
place :(.
You will need a 12-13.8 Volt power supply like the ones they sell at
Radio Shack. Just tell them you have a CB and want a power supply for
it and they should know what to get for you. Radio Shack is probably
not the cheapest place but the best for a beginner :-).
73,
Mike
ko4qc
Sara or Mike Bratcher wrote:
>
> ko4qc wrote:
> >
> > T6766 wrote:
> > >
> > >
> > > I have a Cobra 18RV Mobile CB radio. I have tried several DC power
> > > supplies
> > > (including Radio Shack and Uniden types) and I think I have come to a good
> > > conclusion. When I use a 9 Volt power adopter, the S/TX meter only goes
> > > up to about three (3) LEDs. When I use a 12 Volt adopter, it goes to four
> > > (4) LEDS. And finally when I use a tunable power supply that goes from
> > > 3-17 Volts, I find that the more Volts input I give, the more LEDs light
> > > up, which seems to mean that more RF power is being radiated from the
> > > unit. So I now run it on about 16 Volts,
> > > but the radio needs only 13.8 Volts, and it seems to work best with about
> > > 16 volts. If anyone can confirm or deny this theary, please post it here.
> > >
> > > Thanks,
> > > Eugene
> > need a 'leeneer' then!!!
>
> hello-
>
> Can I use the cord of a old heater. Does it make any diferance what
> wire goes to the hot side. thanks Mike
plug it in.
Ko4qC
ko4qc
Michael volz wrote:
>
> Sara or Mike Bratcher wrote:
> >
> > ko4qc wrote:
> > >
> > > T6766 wrote:
> > > >
> > > I f I were you I would plug it directly into 220-240 volts.Wont even
> > > need a 'leeneer' then!!!
> >
> > hello-
> >
> > Can I use the cord of a old heater. Does it make any diferance what
> > wire goes to the hot side. thanks Mike
>
> cord. Meaning putting 120 Volts into a radio designed for 12 volt input
> unless you want:
> 1. Your radio to be immedieately fried.
> 2. Yourself possibly killed or injured.
> Thanks Joel for the initial idea of directly plugging it in in the first
> place :(.
>
> You will need a 12-13.8 Volt power supply like the ones they sell at
> Radio Shack. Just tell them you have a CB and want a power supply for
> it and they should know what to get for you. Radio Shack is probably
> not the cheapest place but the best for a beginner :-).
> 73,
> Mike
you attend college to arrive at this 'golden tid-bit' of knowledge?:<)
Ko4qC
Sara or Mike Bratcher
ko4qc wrote:
>
> Sara or Mike Bratcher wrote:
> >
> > ko4qc wrote:
> > >
> > > T6766 wrote:
> > > >
> > > >
> > > > I have a Cobra 18RV Mobile CB radio. I have tried several DC power
> > > > supplies
> > > > (including Radio Shack and Uniden types) and I think I have come to a good
> > > > conclusion. When I use a 9 Volt power adopter, the S/TX meter only goes
> > > > up to about three (3) LEDs. When I use a 12 Volt adopter, it goes to four
> > > > (4) LEDS. And finally when I use a tunable power supply that goes from
> > > > 3-17 Volts, I find that the more Volts input I give, the more LEDs light
> > > > up, which seems to mean that more RF power is being radiated from the
> > > > unit. So I now run it on about 16 Volts,
> > > > but the radio needs only 13.8 Volts, and it seems to work best with about
> > > > 16 volts. If anyone can confirm or deny this theary, please post it here.
> > > >
> > > > Thanks,
> > > > Eugene
> > > need a 'leeneer' then!!!
> >
> > hello-
> >
> > Can I use the cord of a old heater. Does it make any diferance what
> > wire goes to the hot side. thanks Mike
> plug it in.
> Ko4qC
--
Now your kidding i know. Im not stuped. ok. Mike
Kip Martin
With all things said I think Dan witnessed:
The higher potential appled from the voltage source, the less likely
the voltage at transmit was weak due to the current draw. Idealy you
want the 13.8 that the manifacturer specified, but this gets tricky
for a power supply scnerio. I have a power supply that is adjustable,
(13.4 Volts - 15.volts). I have noticed that the transmit power is not
at its max at 13.4 volts. The sudden rush of current is effectively
dropping the voltage across the source. If I crank it up to 15 volts
the transmit is better. Your logic is sorta correct. The higher the
potential before transmit, the better chance you'll get the full wattage
output. The tradeoff is that your over working your voltage regulator
inside the radio. So the ENTIRE TIME you aren't transmitting, thus the
voltage is well over 13.8, you are working the regulator of the CB to
death. You may see a better result with a charger attached to a battery.
You may need extra filtering if the charger creates noise. The
advantage to the battery: It can take the sudden pull of current better
than any power supply can. Having a voltage applied to the radio of
over 13.9 or say 14 volts can cook the internal voltage regulator. So
your better choices for supplying that radio includes: A better power
supply that is rated at higher current. A battery and charger. (Bulky
and messy but will do the best job, if you don't have problems with
noise from the charger.) Or a voltage supply of over 13.8 volts that you
can test dropping to 13.8 on transmit. This option will work you
internal regulator of the radio, so you have to judge if the output is
worth it.
My choice: I'd go with the battery. (If I've got the room). Batteries
are rated for as much as 700-900 cold cranking amps. For under $100.
The chargers vary but usually are 10 amps or more. The tricky park is
the noise filtering.
--
Kip Martin
E-mail sl...@cc.usu.edu
http://www.declab.usu.edu/~sl0ym/index.html
Adam Tullis
no it = blowed up radio
T6766 <t6...@aol.com> wrote in article
<19970329031...@ladder01.news.aol.com>...
DAN 1508
also removing the D26 diode and running a jumper across will boost your
power and help on the mod a bit to.
Steven Williams
The reason why this works is that most CB radios are designed to work
within the automotive environment. Most auto electrical systems vary in
their voltage output from 12 volts up to about 16-17 volts. The CB will
operate on anything from 10 volts or so up to around 15-16 just fine and
you will get more output power simply due to the fact that the output
transistors have more to work with. However it is still illegal to operate
with more than 4 watts output.
ke4...@radia1.com
Eugene it is simple P=IE which is Power equals volts times current.
All though I (current) is more important. A CB radio is AM which using
CB slang "Swing" is more important. On 9 volts the radio is not
getting enough volts (no matter how much current is available) to
drive the radio to full legal output power. At 16 you all it can
handle which is actually to much and is bad for the radio in the long
run. Also if you use the variable power supply, when it is on 16 volts
you have less current available to the radio, so you loose "swing". It
would be best to use a battery because you have constant voltage with
needed current on demand. Also with a battery you have no power supply
AC ripple on the DC sorce. Warning: Remember never ever run the radio
with a charger hooked to the battery. But if you run it off the PS set
it for about 14.5 to 15.0 VDC. This is safe and most good fixed high
current PS for 13.8 VDC car equipment put out about 15 VDC at 7 to 10
amps. Also if you are carefull with your wiring and know that
everything is hooked correctly, you may want to check the fuse value.
A low number means faster, better protection, but also means that it
will limit current flow during the "swing" of the AM RF signal. I have
put 5 amp fuses in my power cord when it came with a 2 amp from the
factory. The only real draw back to this is if the radio shorts, it
gets more current before the fuse blows, meaning more damage can
happen inside the radio before power is removed. Do not go to big on a
fuse size increase. The radio can only use so much current and if it
does short you do not want to burn down the place. The best clue that
the radio needs to go up one size is clipping due to lack of current
or a bent or glowing fuse during heavy use (assuming the radio has no
defects or shorts of course).
Remember to be carefull and the higher voltages only shorten the life
of your radio. Current is more important. And if you radio puts out 7
watts at 14.5 volts and 9 watts at 16.5 volts, nobody can hear the
difference and you are not talking any farther. The difference of 2
watts is unhearable and is not even 1/100 of an S unit. In other words
it is not worth the trouble or the reduced life span of the radio.
Brian Ellsworth
On Thu, 01 May 1997 06:07:34 GMT, ke4...@radia1.com wrote:
>Eugene it is simple P=IE which is Power equals volts times current.
>All though I (current) is more important.
>
which (if either) of these statements is true... First year electronic
students will assure us the equation is true. (although i doubt it is
very relevant to answering the original question.) The statement about
current being 'more important' is a joke. Any fifth grade math student
will back me up on this one.
>A CB radio is AM which using
>CB slang "Swing" is more important.
Swing this. The amount of energy in the sideband is what is important.
That is, the energy in the sideband AND within the receivers bandpass
limits. If you want more swing don't hold a golf ball between your
cheeks when you walk.
>On 9 volts the radio is not
>getting enough volts (no matter how much current is available) to
>drive the radio to full legal output power.
i thought you said 'current was more important'....
>At 16 you all it can
>handle which is actually to much and is bad for the radio in the long
>run. Also if you use the variable power supply, when it is on 16 volts
>you have less current available to the radio, so you loose "swing".
>
Are you making this up? You do not 'loose swing' because there is
'less current available'... There may be a number of factors which
would cause the radio to reduce it's output when modulated. Current
limiting is indeed one of them but to authoritatively state that is
the case here is bull crap. In fact in this case it is probably NOT
the relevant factor. More likely, a regulator in the radio or a
specific component's gain is limiting the maximum peak output.
16 volts may be slightly stressing the components in the radio, but it
is primarily a thermal issue at this voltage. If you tend to 'key-up'
for long intervals you'd better watch the temperature of that final!
> It
>would be best to use a battery..... <EDIT CLIP>
>
Ah, don't do this. It's a dumb idea. To get a large enough battery to
last for more than a few minutes you'll have to get a lead-acid type
like a car or marine battery. Charging that thing in the house is
absolutely crazy. Even so called 'sealed' gelcel types can out-gas
combustibles (hydrogen) when charged. If you can keep the charge rate
low enough you might get away with it, but is not really a safe
practice...
>Remember to be carefull and the higher voltages only shorten the life
>of your radio.
>
Ok. So what. The question is: How much will it shorten it?
>Current is more important.
Nope.
>And if you radio puts out 7
>watts at 14.5 volts and 9 watts at 16.5 volts, nobody can hear the
>difference and you are not talking any farther.
Yep. Going from 7 to 9 watts isn't going to make a noticeable
difference.
HYPE
Brian Ellsworth wrote:
-
- On Thu, 01 May 1997 06:07:34 GMT, ke4...@radia1.com wrote:
- -Eugene it is simple P=IE which is Power equals volts times current.
- -All though I (current) is more important.
- -
- My fifth grader read this, saw the obvious contradiction and asked me
- which (if either) of these statements is true... First year electronic
- students will assure us the equation is true. (although i doubt it is
- very relevant to answering the original question.) The statement about
- current being 'more important' is a joke. Any fifth grade math student
- will back me up on this one.
-
- -A CB radio is AM which using
- -CB slang "Swing" is more important.
-
- Swing this. The amount of energy in the sideband is what is important.
- That is, the energy in the sideband AND within the receivers bandpass
- limits. If you want more swing don't hold a golf ball between your
- cheeks when you walk.
-
- -On 9 volts the radio is not
- -getting enough volts (no matter how much current is available) to
- -drive the radio to full legal output power.
-
- i thought you said 'current was more important'....
-
- -At 16 you all it can
- -handle which is actually to much and is bad for the radio in the long
- -run. Also if you use the variable power supply, when it is on 16
volts
- -you have less current available to the radio, so you loose "swing".
- -
- Are you making this up? You do not 'loose swing' because there is
- 'less current available'... There may be a number of factors which
- would cause the radio to reduce it's output when modulated. Current
- limiting is indeed one of them but to authoritatively state that is
- the case here is bull crap. In fact in this case it is probably NOT
- the relevant factor. More likely, a regulator in the radio or a
- specific component's gain is limiting the maximum peak output.
-
- 16 volts may be slightly stressing the components in the radio, but it
- is primarily a thermal issue at this voltage. If you tend to 'key-up'
- for long intervals you'd better watch the temperature of that final!
-
- - It
- -would be best to use a battery..... <EDIT CLIP>
- -
- Ah, don't do this. It's a dumb idea. To get a large enough battery to
- last for more than a few minutes you'll have to get a lead-acid type
- like a car or marine battery. Charging that thing in the house is
- absolutely crazy. Even so called 'sealed' gelcel types can out-gas
- combustibles (hydrogen) when charged. If you can keep the charge rate
- low enough you might get away with it, but is not really a safe
- practice...
-
- -Remember to be carefull and the higher voltages only shorten the life
- -of your radio.
- -
- Ok. So what. The question is: How much will it shorten it?
-
- -Current is more important.
-
- Nope.
-
- -And if you radio puts out 7
- -watts at 14.5 volts and 9 watts at 16.5 volts, nobody can hear the
- -difference and you are not talking any farther.
-
- Yep. Going from 7 to 9 watts isn't going to make a noticeable
- difference.
I agree with you 100%. whoever told or taut mister <ke4...@radia1.com>
needs to learn a fue things. I want to know why he thinks you should use
a 12v batery over a power suply. Every mobile radio ive seen has ben
rated a 13.8v, you can get power suplys to mach that exaclt so your not
underpowering or overpowering thus making the radio happy.
LATER,
HYPE
Zodiac Farmer
On 6 May 1997, lightning wrote:
-=>
-=>
-=> When does the P in p=i*e =rf power output??
-=>
-=> I have not seen this equation work out yet say 14 volts * 100 amps
-=>doesn't =1400 watts rf output.
-=>
-=>
-=>
it does not equal power output.
Its Ohm's law - but the correct way to use in this application would be
For 1400 Watts at 14 volts, you need to supply 100 amps. But that is only
in theory, you would need more current because of loss.
lightning
HYPE <cus...@clinton.net> wrote in article <336A16...@clinton.net>...
> Brian Ellsworth wrote:
> -
> - On Thu, 01 May 1997 06:07:34 GMT, ke4...@radia1.com wrote:
> - -Eugene it is simple P=IE which is Power equals volts times current.
> - -All though I (current) is more important.
> - -
> - My fifth grader read this, saw the obvious contradiction and asked me
> - which (if either) of these statements is true... First year electronic
> - students will assure us the equation is true. (although i doubt it is
> - very relevant to answering the original question.) The statement about
> - current being 'more important' is a joke. Any fifth grade math student
> - will back me up on this one.
> -
When does the P in p=i*e =rf power output??
I have not seen this equation work out yet say 14 volts * 100 amps
Bernard Cormier
In article <01bc59cf$ecdf70e0$4b5c...@magpage.com.magpage>, j-...@usa.net
says...
volts is I=V/R or 14/50 =.28 amps. The power will be 14volts *.28 amps = 3.92
watts. In other words if your load was .14 ohms then the current would be 100
amps and the resistor would dissipate 1400 watts and be very HOT. The
formulas apply if you apply it correctly.
--
NOTE: The header e-mail address is a e-mail blocker. ****
NOTE: To e-mail me use: corm...@nbnet.nb.ca ****
Bernard Cormier (USA1028)
Moncton N.B. Canada
Have a nice day!
----------------
Bill Eitner
lightning wrote:
> When does the P in p=i*e =rf power output??
After you factor in efficiency.
>
> I have not seen this equation work out yet say 14 volts * 100 amps
> doesn't =1400 watts rf output.
Using your example: 14 volts times 100 amps equals 1400 DC watts
INPUT. No amp is 100% efficient. You have to consider the
efficiency of the amp. Most of the CB-grade RF amps out there
are between 55 and 65 percent efficient. That means the amp
in your example would put out between 770 and 910 watts of
RF power.
So, if you want to figure output power from input power,
the equation would look something like this:
DC Voltage X DC Current = Input Power X Efficiency = Output Power
You should remember that. It's the cheapest way I know of to
realistically judge an amplifier's output power. It's alot
easier come up with an accurate volt meter and DC ammeter than
it is to come up with an accurate wattmeter and high-power
dummy load combo.
--
----------------------------------------
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___ | ___ Talk to me live via
A Cool Talk... Here's how:
/ | \ 1. Launch Cool Talk and your
-=[Bill Eitner]=- III web browser.
III 2. Go to: http://live.netscape.com
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Mike Volz
lightning wrote:
>
> HYPE <cus...@clinton.net> wrote in article <336A16...@clinton.net>...
> > Brian Ellsworth wrote:
> > -
> > - On Thu, 01 May 1997 06:07:34 GMT, ke4...@radia1.com wrote:
> > - -Eugene it is simple P=IE which is Power equals volts times current.
> > - -All though I (current) is more important.
> > - -
>
> When does the P in p=i*e =rf power output??
>
> doesn't =1400 watts rf output.
You must figure in the power drawn by all the radios circuitry and then
the efficency of the equipment.
Zodiac Farmer
-=>> When does the P in p=i*e =rf power output??
-=>>
-=>> I have not seen this equation work out yet say 14 volts * 100 amps
-=>>doesn't =1400 watts rf output.
-=>>
-=>Your normal antenna impedance is 50 ohms so the rf current in it from 14
-=>volts is I=V/R or 14/50 =.28 amps. The power will be 14volts *.28 amps = 3.92
-=>watts. In other words if your load was .14 ohms then the current would be 100
-=>amps and the resistor would dissipate 1400 watts and be very HOT. The
-=>formulas apply if you apply it correctly.
that would only be correct if the current and the voltage were in phase.
We're talking AC here not DC - 50 ohms is the 'impediance' not the
resistance. It is a load for the output
Marty Kirkland
Huh? This is not correct in any way.
Nobody said voltage times current was power output! 50 ohms and 14
volts has nothing at all to do with it. Go read a book about this stuff
if you want to know.
Douglas Dumire
Marty Kirkland <mkir...@electrotex.com> wrote in article
<337127...@electrotex.com>...
Got some of you thinking I have seen a numerous of times on this news
group that people use the equation p=i*e in reference to power output as
in rf power = current times volts. when the p is total power displaced by a
transmitter or amp .
and no 2 amp are of the same efficiency. why do we put heatsink on amps? To
displace the heat from the transistors this is also power output so how do
you figure this in? This equation does not work in rf applications.
Chad Moore
> >
> > Hi,
> >
> > I have a Cobra 18RV Mobile CB radio. I have tried several DC power
> > supplies
> > (including Radio Shack and Uniden types) and I think I have come to a good
> > conclusion. When I use a 9 Volt power adopter, the S/TX meter only goes
> > up to about three (3) LEDs. When I use a 12 Volt adopter, it goes to four
> > (4) LEDS. And finally when I use a tunable power supply that goes from
> > 3-17 Volts, I find that the more Volts input I give, the more LEDs light
> > up, which seems to mean that more RF power is being radiated from the
> > unit. So I now run it on about 16 Volts,
> > but the radio needs only 13.8 Volts, and it seems to work best with about
> > 16 volts. If anyone can confirm or deny this theary, please post it here.
> >
> > Thanks,
> > Eugene
> need a 'leeneer' then!!!