RE: [TCML] pig Jacobs (don't totally blow off resistive ballasting)

["J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>]

If the element is immersed in water, even if it fails
"open", it may not actually be completely "open"
because of the water.

...which brings me to another suggestion for a
ballast:  My first pig ballast was just two copper
pipes held in parallel by nylon bolts and immersed in
a plastic garbage can full of water.  I put a PVC
sleeve over one of the pipes which could be raised or
lowered to vary the resistance, then doped the water
with baking soda until I'd achieve the desired
resistance range.  It worked great and allowed for
very smooth control, albiet farily lossy.  Since the
PVC had to be raised to reduce the resistance, gravity
would naturally turn the power down if I let go of the
control handle (A PVC "T" joint with another small
section of PVC sticking off the side).  Also, this
meant that the heat production was always near the
bottom of the garbage can, allowing for plenty of
convection cooling.  It took quite a while for the
water to get hot, even with many kVA's involved.

So, despite the lossiness of resistive ballasting,
it's still hard to beat for simplicity and smoothness
of control.  And also (probably) cost.  Check the
prices on 500ft rolls of #10 wire these days ... :-(((
 Then compare to the prices of a few short sections of
PVC, water pipe, and a plastic Rubbermaid (or similar)
garbage can.  I think I spent about $20 total
(although I already had the PVC).

My ballast these days is a big variac which I lucked
into at a great price.  If you want to build a big
variable inductor for cheap, however, Goodle for
"slide choke" and "tesla" and you'll get lots of good
hits, I'm sure.

Cheers,
Aaron, N7OE

--- david baehr <dfb25@xxxxxxxxxxx> wrote:

> 
> Yea, 50+ amps is high for a JL , but, if ya wanna
> see the big , thick plasma ( ? ) , ya gots too :-)
>  
>           Oh, if the element fails , this would be
> an 'open' circuit , woulnt it ?? it would just turn
> off ?  
>  

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