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Old August 23rd 04, 10:09 PM
JGBOYLES
 
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I have no way to measure inductance.

To know what size Cap. you will need, you will have to have some idea of the
inductance. One easy way to check the inductance uses an AC voltmeter a
variable resistor (pot), and a low voltage 60 hz voltage source like a 120/12
volt transformer.
Hook the inductance and the variable resistor in series. Apply the 60 hz
source across the series combination. Adjust the pot until the voltage dropped
across the pot and the inductance are equal. Read the value of the pot, this
is now equal to the inductive reactance of the coil Xl plus that 18k DC
resistance you said you measured. From this you should be able to calculate
the approximate inductance of the coil, and the Capacitor value needed to tune
it to 8 hz.
Use L=(Xl+18k)/2*pi*60
and then 8^2=1/4*pi^2*L*C and solve for C.
73 Gary N4AST
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Old August 24th 04, 12:21 AM
Tam/WB2TT
 
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"JGBOYLES" wrote in message
...
I have no way to measure inductance.


To know what size Cap. you will need, you will have to have some idea of

the
inductance. One easy way to check the inductance uses an AC voltmeter a
variable resistor (pot), and a low voltage 60 hz voltage source like a

120/12
volt transformer.
Hook the inductance and the variable resistor in series. Apply the 60

hz
source across the series combination. Adjust the pot until the voltage

dropped
across the pot and the inductance are equal. Read the value of the pot,

this
is now equal to the inductive reactance of the coil Xl plus that 18k DC
resistance you said you measured. From this you should be able to

calculate
the approximate inductance of the coil, and the Capacitor value needed to

tune
it to 8 hz.
Use L=(Xl+18k)/2*pi*60
and then 8^2=1/4*pi^2*L*C and solve for C.
73 Gary N4AST


Gary,
This sounds like a good idea. Only thing I would worry about is that given
the dimensions of the coil, it may be resonant below 60 Hz.

Tam/WB2TT


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Old August 24th 04, 12:44 AM
JGBOYLES
 
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This sounds like a good idea. Only thing I would worry about is that given
the dimensions of the coil, it may be resonant below 60 Hz.


Hi Tam, Well, guess you are right, the self resonant frequency of the coil may
be below 60 hz and would make the measurements different, this compounds his
problem.
73 Gary N4AST
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