Re: Insulation on Primary windings (fwd)
---------- Forwarded message ----------
Date: Sat, 14 Feb 1998 08:08:40 -0800
From: Bert Hickman <bert.hickman-at-aquila-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Insulation on Primary windings (fwd)
Tesla List wrote:
> ---------- Forwarded message ----------
> Date: Sat, 14 Feb 1998 03:22:07 +1100 (EST)
> From: Rodney Graham Davies <Rodney.Davies-at-anu.edu.au>
> To: tesla-at-pupman-dot-com
> Subject: Insulation on Primary windings
> Hi All,
> Say, I'm designing a new small coil and am deciding on what type of
> conductor to use for the primary.
> I'm building a 3"x12" coil and am looking at a conductor diameter (for
> the primary) of 0.125". I could go for copper pipe, or I was thinking
> standard 30Amp Earth wire (which is about the same diameter).
> Refering to my subject line, Insulation on the primary, why is it, that
> for every coil I've seen (from miniature to huge), the primary windings
> *never* have any insulation... why is this so?
> Therefore, I was thinking that I might leave the insulation on the
> Earth wire that I'll use on the primary... good idea?
> Weird thought I know, rather trivial, but it's something I've not thought
> about before...
The reason that most primaries aren't insulated is to permit ease of
tuning. In many systems, the tank cap is a fixed size - tuning is
accomplished by tapping at the correct turn on the primary to get the
You can leave the insulation on the primary and tune the system by means
of adding/removing smaller values of tank capacitance (easy for example
if you're using salt water caps, or have made an oil-immersed variable
cap). Or, you can cut away the insulation only where you need to make a
Safe coilin' to you, Rod!
-- Bert --