Adj. Pri. Cap

From:  John H. Couture [SMTP:couturejh-at-worldnet.att-dot-net]
Sent:  Saturday, January 24, 1998 11:47 AM
To:  Tesla List
Subject:  Re: Adj. Pri. Cap

At 01:13 PM 1/23/98 +0000, you wrote:
>From:  Rene Caldera [SMTP:Rene-at-compuserve-dot-com]
>Sent:  Friday, January 23, 1998 12:31 AM
>To:  INTERNET:tesla-at-pupman-dot-com
>Subject:  Adj. Pri. Cap
>>>Are you thinking about bringing out external taps or are you looking to
>make it infinately adjustable, to adjust it while in operation. A number
>of coilers have used either method with success. An air-insulated
>variable transmitting capacitor (1/4" or so spacing between plates)
>which is immersed in transformer oil will work quite well when connected
>across your main cap(s) to provide precision tuning. However, be very
>careful that you are not going to make accidental contact with either
>lead of the cap - I've seen primary RF jump about 2.5". Use a long shaft
>made from a good insulating material.
>Safe cappin' to you!
>-- Bert --<<
>I'm thinking of verticle plates with a sliding action. One side stationary
>the other slides in and out. 90mil of PE inbetween plates and the whole
>thing in a tank of mineral oil.
>Sound good?
>Rene Caldera - So. Calif.

  Rene -

  I used a barn door adj cap. Two pieces of plexiglas with alum foil
cemented to them. The plexiglas pieces were connected with a hinge and a
long handle. The capacitance could be varied from about 20 to 150 pf. It
worked very good with a larger capacitance in parallel. 

  John Couture