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Re: Still mystified by odd TC behavior, what gives?
Original poster: "Jonathan Peakall by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jpeakall-at-mcn-dot-org>
Secondary is 14"
Terminal capacitance unknown, currently on the coil is a copper toilet
second cap is .0028
small primary is aproximatly 245" long
large primary is aprox. 378" long
You are quite right about the tuning estimate, this is very close to
where the sweet spots are for the coil when operating with the two caps
I am going to shut of the computer and go see what happens with the
priamry out of the circuit and check.
Thanks much for your time.
> There isn't enough information there to really understand how
> SHOULD behave. Things which would help:
> 1. Length of secondary,
> 2. Terminal capacitance,
> 3. Length of the two primaries
> 4. Capacitance of "the other cap".
> Making a rough estimate here I find that the resonant frequency of your
> secondary with no added top loading is of the order of 1000 kHz. The
> inductance of your smaller primary is about 30 uH, that of the larger is
> about 40 uH. The resonant frequency of the smaller primary with 0.023
> ufd would be about 195 kHz, that of the larger would be around 165 kHz.
> As a rough guess, the thing should tune with around 6 turns on the
> larger primary and 5 turns on the smaller. It seems to me that it is
> quite possible that you never got the primary tuned to the right
> frequency and that your new capacitor will be OK. You didn't mention
> what happens when you hook it to the transformer and gap without the
> primary coil in series.