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Old December 11th 03, 09:50 PM
Donald Sherwood
 
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I'll add to that those wonderful "Monster caps" that are those High farad
values of 5, 15, and 50 Farads (Thanks alot Alumapro, and Pheonix Gold) are
junk. Even if the measured or stated (ESR) is low. The other problem is ESL,
equivlent series inductance. The ESL is kind of like a the responsecurve of
a VSWR curver through the frequency rage of a Antenna.

The ESL changes with freq. Now that may be low with a DC circuit. But the
minute you start fluctuating that current and voltage, the ESL Will start to
rear it ugly head. Remember L = Inductace is the Opposition to current flow.

If you really want some good imput on this hit up Carsound.com Forums and
look up under Richard Clarks Archived topis for Capacitors.

"Frank Gilliland" wrote in message
...
In , "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.
Could this same principle be applied to ssb, I think it can.
place a 1 farad audio cap inline with the power lead to say a Texas star
dx1600 and you run the rig on ssb the cap will discharge under peak load
giving you a higher average output.

Any comments? (and I mean REAL comments)



Even though you are a troll, you actually raise a good point here. Now I'm
assuming you meant that the capacitor is connected in parallel with the

power
supply leads, because if it were connected in series you would get no

power.

In an SSB amp the RF power follows the audio, and will therefore have a

current
draw that varies at audio frequencies. A capacitor placed across the power

leads
of the amp, when combined with the inherent resistance of the wires from

the
battery, creates a simple low-pass filter which will help smooth out those
'audio' peaks. The bigger the amp, the bigger the cap. And keep the leads

from
the amp to the cap as short as possible.

BTW, this type of filter won't do much in AM service since the current

drawn by
the amp in AM is fairly steady (at least it -should- be, i.e, it's not
amplifying a signal loaded with overmodulation and 'swang'). But it -will-
filter out noise from the power supply.

A word about those 'moster caps' for audio amps: Most of them have a high
equivalent series resistance (ESR) which defeats the purpose of using

them. They
behave more like a rechargeable battery than a capacitor. Locate your

local
computer junkyard and get some of those big electrolytics from the

mainframe
power supplies. Typically, just one 100,000 uFd aluminum electrolytic has

a
lower ESR than a 1.0 farad 'monster' cap. Also remember that you can

reduce the
ESR by putting capacitors in parallel. Ten 10,000 uFd caps in parallel

will have
a much better ESR, and therefore much better filtering ability, than one

100,000
uFd capacitor of the same type, even though the total mFd value is the

same.





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

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