[Amps] series-connecting a split-stator variable cap

[Will Matney]

Val,

How is it possible to change the voltage rating unless the air gap spacing is farther apart? I can't see how you can make a series circuit if the rotors are on a common aluminum shaft unless there's an insulating busing between the sections dividing the shaft up. Most every air variable I have ever seen that's 2-3 section, the rotor shaft is a single aluminum or brass shaft with all the plates pressed on it for all the sections. The stator is divided up and can be jumped over to add the capacitance of each section. To series it, each section would have to be insulated, both rotor and stator. Then, I could see dividing the voltage up by two. That's the only way I can see doing it myself.

Best,

Will




*********** REPLY SEPARATOR  ***********

On 3/20/06 at 9:24 AM Val wrote:

>Will,
>
>The sections will be put in series by the common rotor. Each of the 2
>stators ends will be capacititor's end. The rotor and the frame will be
>insulated and will work OK. Have done that.
>
>73, Val LZ1VB
>
>> The capacitors rotor has to go to ground, and the stator to the tank coil
>to work. Generally, the rotor is connected through >frame ground via a
>wiper. The stator is insulated. There's no way of increasing the voltage
>unless the plates are spaced >further apart. If you series the sections by
>using a jumper across the screws, you increase the capacitance, not cut it
>in half. >You have to paralell them to do that and there's no way to do it.
>To get less capacitance, or cut it in half plus raise the >voltage, remove
>half the plates at every other plate. That will increase the air gap and
>the
>voltage rating, plus cut the >capacitance of the section in half. Those
>plates will come off as they're just pressed on.
>
>
>The sections will be put in series by the common rotor. Each of the 2
>stators ends will be capacititor's end. The rotor and the frame will be
>insulated and will work OK. Have done that.
>> *********** REPLY SEPARATOR  ***********
>>
>> On 3/19/06 at 4:19 PM Scott Townley wrote:
>>
>> >I have a dual (split-stator) 20-100pF air cap, 0.040" gap (so ~1500V)
>> >I need a single 15-50pF, 3000V for a tank tuning cap.
>> >So is there any reason I can't simply series-connect the split stators
>and
>> >float the rotor?  Obviously the rotor must be isolated from the chassis
>> >now, and I won't get 20/2=10pF min due to frame effects, but I only need
>> >15...anything I'm missing?
>> >TIA,
>> >
>> >
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>>
>>
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