RadioBanter - ssb, linears, and caps

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The DC input power follows the audio input, compressed or not. Is that concept
too difficult for you to comprehend?

Trying to create a divergence away from the truth?

Hardly. I'm trying to make you understand a fundamental concept of radio
communications that has eluded your meager education.

The truth is not gained by equating DC input to output. The truth is
gained by comparing SSB audio compression levels to that of HI- FI
audio compression levels.

You are truly lost.

More accurately you are truly lacking in common sense.

A compressed audio signal at its highest compression would
approach a single tone or carrier as far as a SSB amp goes. With
this much compression no reasonable amount of capacitors can
be useful on the 12 volt lead.

On the other hand just and intermittent spike here and there will only
require a minimal amount of capacitance on the 12 volt lead and can
make a difference. If you graphically plotted the capacitance needed
for total compression (carrier), to no compression (spikes), then
you would have a linear graph that would show that the amount of
capacitance needed is directly related to the percent of the duty of
the amp.

The caps work better if the have time to recover. If they can't
recover then the are useless. A SSB signal has more compression than
a HI-FI signal., so dx1600 with one farad on SSB would be one of those
points in between. total compression and no compression It wouldn't
have adequate time to recover in order to be worth the cost.

JJ wrote:
Dr. Death wrote:

no...on car audio its in series with the positive feed

I don't think a capacitor in series with the DC power lead of a car
audio system is going to work very well.

wrote in message
...

On Mon, 8 Dec 2003 03:23:00 -0600, "Dr. Death"
wrote:

I noticed that a lot of high end auto audio systems use a capacitor in
series with the main power lead to the amplifies so the amp hits
harder.

This is more audiophool nonsense than anything else.

This does indeed help with audio amplifiers (especialy subwoofer amps) a
large capacitor (ie. 1 Farad) is placed in *paralel* (as in across) the
+ and - power leads,just like the battery would be.The cap acts much
like a filter cap in a power supply.
I put a little over 0.1F (100,000uf) on my 400W sub amp,and it made a
big difference.I suspect it might be useful for mobile RF amps aswell.

Just a note,Think of ESR as how fast a capacitor will charge/discharge.
As Frank pointed out,think of slower caps acting more like rechargeable
batteries,that's too slow to filter out audio peaks,let alone RF.
At high current levels,wire resistance becomes an important factor,and
caps can help with the inherent voltage drop/sag.

Frank Gilliland wrote:

In 9McBb.1407$8y1.13274@attbi_s52, "MasterCBer" wrote:

Well lets see here DOC and Frank
Have you tried a Large farad cap on your amp?

I use caps on just about everything mobile. They work great to get the low-end
from an audio amp. No, I don't run an RF amp, base or mobile. Yes, I have
intalled a few; and yes, they do run better with a big cap on the power leads.
By 'better' I mean that the audio is cleaner and IMD is reduced.

I thought not.

No you didn't.

So unless you have then don't cut it.

Frank you need to learn what ESR is you ****en dum ass.
These cap have a very LOW ESR as I said in my first post I or do you not
read very well.

From Cornell Dubilier:

381LX473M016A452
47000 uFd @ 16 VDC
0.017 ohms @ 120 Hz
0.013 ohms @ 20 kHz

Now you can probably find farad-sized electrolytics -advertised- for lower ESR,
but they don't tell you the frequency or conditions under which that ESR was
measured. There are engineering standards for measuring such things as ESR.
Industry has to deal with these standards all the time. But as long as these
caps are not marketed for industrial use the manufacturers can declare an ESR
that is measured in any way they want, even by measuring the cap in a series
resonant circuit with a high impedance source. IOW, it's a lot of hype, just
like the ridiculous gain figures that are advertised for some CB antennas. About
the lowest -real- ESR you will find among those ultra-high-density caps is about
0.2 ohms, and it will cost you most of a paycheck (two or three paychecks if you
have a McJob).

The problem here is one that has existed since the first capacitor was invented:
There is a tradeoff between charge density (uF per cubic inch) and ESR. Whenever
the physical size of a capacitor gets too large, it usually dictates a different
type of capacitor. A 1 farad air capacitor would have an extremely low ESR, but
it would probably be as big as an aircraft carrier (which would introduce other
problems, but those are ignored for the sake of this example). If it was an
oil/paper capacitor it might be as big as a house. Even an aluminum electrolytic
of 1 farad would still be quite large for a mobile application. So these monster
caps are built with a different type of electrolytic process, one that packs
more farads into a smaller space, but at the expense of increased dielectric
absorption/hysteresis, i.e, a higher ESR.

Put more simply, if these big caps were as good as the advertisers claim them to
be, they would have replaced aluminum electrolytics a long, long time ago. They
haven't. Put even more simply, if it looks too good to be true, it probably is.
If you don't believe me, buy one and measure it yourself. You will need a very
low impedance source and load, then measure the difference in ripple voltage on
a scope. Post the results.

And just to make my point about smaller caps in parallel being better than one
big cap:

381LX472M016H012
4700 uFd @ 16 VDC
0.113 ohms @ 120 Hz
0.085 ohms @ 20 kHz

Put ten of the 4700 uFd caps in parallel and you have 47000 uFd, but with an ESR
of 0.0113 ohms @ 120 Hz and 0.0085 @ 20 kHz, which is better than the 47000 uFd
capacitor. This value would drop the source impedance (in my example from the
previous post) from 0.0163 ohms to 0.0067 ohms, meaning the voltage will only
drop 0.53 volts on a peak. So in this example, the caps give back three-quarters
of the power that is missing from the peaks when run without the caps. Compare
that to any size cap with an ESR of 0.2 ohms.

=============

"...but I admitted I was wrong, Like a man! Something you and QRM
have a problem with. You guys are wrong and you both know it and
are both too small to admit it."
---- Twistedhed ----

=============

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Simple test, Put a scope across the DC supply lines next to the Amp, Look at
the audio effect on the voltage ( SSB mode ), Next hook up a Cap as
discussed, Now look at the audio ripple, if I need to tell HOW to hook up
the scope, then you don't need to brother with this.
Simple enough.

"Steveo" wrote in message
...
William Wallace wrote:
he is
a cber and they have all those cb myths to follow.

You're a CB wanna be troll.