Speaker Noise:
The "pop pop pop" noise is the ignition and is caused by a spark jumping
a gap. It can be either the points, the plugs or a misdirected arc from
the plug wires to a nearby ground. It can also be from the chassis of
the radio being insulated from the vehicle body and it's ground
connection being made only through the antenna shield. I have seen
several radios mounted in consoles that are not grounded. If this is
the case simply running a wire direct from the radio chassis to a nearby
ground (or chassis) should solve the problem. On some radios that are
+/- ground the chassis will "float" neither + or -. On these radios
there is no shield and the chassis must be tied to the chassis to keep
the noise out. To reduce noise generated from the points a .25 (or so)
coaxial capacitor with a short lead on the battery side of the
distributor may help. Resistor spark plugs and resistor (suppressor)
wires will also help also. Old or low quality plug wires will sometimes
"leak" the HV to a nearby chassis component or engine block. The
easiest way to find this it to find a dark place, raise the hood and
look for the flash. Other places to look are electric instruments and
sensors and voltage regulators especially the generator types.
Some thoughts on dual batteries:
First of all you will gain nothing by using two 12 volt batteries in
parallel versus two 6 volt batteries in series if the batteries are
about the same physical size. For instance a given amp hour rating for a
6 volt battery may be 200 amp hours, and the same physical size 12 volt
battery will have an amp hour rating of 100 amp hours. Since it will
take two 6 volt batteries to develop the 12 volts we need they will
retain the 200 amp hour rating. Using two 12 volt batteries in parallel
will double the amp hour rating, but still you will end up with 200 amp
hours. The only advantage of using two 12 volts would be to use a large
switch (200 Amp)to keep one battery as a spare in case the other was
discharged. That's what we do on boats because they are real hard to
push start. Charging two twelve volt batteries with diode isolation is
a compromise at best. The voltage drop across a diode is .7 volts and
this will not allow your battery to reach full charge unless the
regulator is adjusted to compensate for the loss. There are some
expensive devices that sense voltage on two batteries, then direct the
charge current to the battery that needs it through a relay. These
eliminate the losses and work good, but at a high cost.
I hope this helps, now I feel that I can ask more of my dumb mechanical
questions!
Mark Endicott
70 Midget
Nashville
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