Re: Cable question
From: Gary Lau 01-Jan-1998 2306[SMTP:lau-at-hdecad.ENET.dec-dot-com]
Sent: Thursday, January 01, 1998 9:41 PM
Subject: Re: Cable question
>From: Andrew Chiin[SMTP:chinny-at-ozemail-dot-com.au]
>Just wondering what kind of cable should I use to connect a NST to the
>protection network, i.e. the chokes, bypass caps & SG? I have a few metres
>of neon cable. I'm guessing this is quite suitable for this purpose.
The wire gauge doesn't matter at all, the appropriate type depends only
upon the routing of the wires. If your arrangement is very short and
direct with the wires in a more or less permanent configuration and not
draping on other components, any small gauge conductor with enough
insulation to discourage corona is fine. If however the setup is the
sprawning type with wires draped across the floor and likely to flex as
the rig is moved, neon sign cable should be used for those portions.
>Also what kind of cable should I use to connect the Tesla tank components.
>I presume there's quite a large current flowing through here and neon cable
>can't hack it. Or am I mistaken.
You're dead on. Use the biggest and shortest copper conductors you can
manage, like 1/2" wide or greater copper sheet. Also, arrange the
components in your rig to keep connections as short as possible.
>And finally what kind of wire should I use to wind the chokes?
For single layer air core chokes, use the thinnest enamel wire you can
find. More turns per inch = more inductance. Resistance is not a
problem as you should have resistors in series with your chokes anyway,
and any gauge you can manage will be several times as thick as what NST
secondaries are wound with.
For ferrite or powdered iron cores, you must insulate these to the hilt,
using wire with heavy insulation and insulating the cores. Unfortunately
it's not possible to find very fine wire with thick insulation. Coax
cable with poly core insulation, stripped of it's shield is often used.
I found some 22AWG wire with .09" OD poly insulation, called "antenna
wire" at a ham fest. Remember that voltages far in excess of your NST's
voltage are easily developed across chokes and end-end or layer-layer
insulation must protect against this.
Waltham, MA USA