In a message dated 12/26/2003 8:53:26 AM Eastern Standard Time, tr6@kc4sw.com
writes:
I was under the impression that while it is called a radio suppression
cap, that a large part of it's function has to do with the pulse shape
of the energy sent to the spark plugs.
One of my first introductions to the physics of Electronics came
explaining the waveform generated by a collapsing magnetic field in a
coil that had a capacitor in parallel to it. The capacitor causes the
output to be a damped shape rather than abrupt shape.
IMHO removing the capacitor may (notice the hedge) effect the
performance of the engine and the life span of the plugs, cap, rotor.
Of course the rest of the consideration is that most of these cars came
without a radio, and what manufacturer ever puts in a part that protects
some other car than it's own.
Steve,
The function of a capacitor in the ignition circuit depends on it's location
in the circuit, the frequencies involved, and the relative values of the
capacitance, resistance, and inductance involved. The capacitor (condenser)
inside
the distributor body, and connected around the points and in series with the
coil primary, is VITAL to the performance of the ignition system. Contrary to
popular opinion, the function of this condenser is NOT to protect the points,
but to speed up the decay of the primary field. Point protection is just a
beneficial side effect. Without this condenser, the field decay in the primary
would be so slow that the secondary output would to too low to fire the plugs.
The external capacitor is located and sized to shunt to ground the high
frequency noise from the arc created when the points open. Without this
capacitor,
the noise would be shunted to ground through the wiring harness, which, acting
like an antenna, would radiate the noise into the radio circuitry.
As was pointed out earlier, this capacitor is made of unobtainium, so there
are many cars running around without it, mine included, with no deleterious
effects on the operation of the ignition system. Most modern radios come with
their own noise suppression, so there are no harmful effects on radio reception
either from the deletion of this capacitor.
I'm on the digest version of the list, so if someone else has already
answered this post, my apologies! I didn't mean to step on Dicks toes with my
previous post that he had already answered.
Regards,
Dan Masters
Alcoa, TN
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