Re: Spark gap metals

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>

Hello Steven.

> Why are ya'll so concerned about the metal your spark gaps are made of?

Besides many other points, not all metals are good conductors at RF 
frequencies.

> As long as your the metal has enough surface area( to radiate heat) and you
> keep blowig air on it(like with a muffin man... I mean fan), it won't melt
> and it would be fine.
The place where the spark happens to travel might still get very hot.
Some materials have less thermal conductivity, making it hard for the heat to
travel away from that point to your fan.
> You could even make a fine spark gap by replacing the copper pipes or
> tungsten rods with old heat sinks from scrap computers.

Just as with the CPU-Coolers you refer to, the biggest cooler
won't help if you can not get the heat out of the CPU core.... similar with 
SG's
If the metal becomes hot enough, even for a short period of time, this might be
sufficient to cause significant oxidation or even causing the metal to burn
which is very spactacular with aluminium and hard to extinguish....
But, while the fins of the "Intel Boxed" Coolers is aluminium, there is a 
pretty
huge 2" by 2" copper chunk press fitted in the center of these beasts... maybe
usefull.
You could fit some 1/4" tungten rod in the copper part and use 2 of these units
facing
each other to make a low power SSG...

>Besides, isn't > tungsten expensive?

yes it is indeed, but you can get small diameters for reasonable prices from
WIG welding tips. Tungsten is a superior chioce for higher power levels.
It corrodes less, keeping your gap clean and electrode shape and distance
equal over a longer runtime.

> Trust me, I may be new at this, but I can tell you that fan cooled heat
> sinks or at least copper pipe(the longer the better) will do just as good,
> if not better, than tungsten rods.

Sorry, but you just can't. With low power levels ( and with lots of airflow
maybe even bigger ) Copper pipes work great, but when you really want
to switch bigger amperage currents they will just melt away.
But there are still other reasons for building RSG's with tungsten electrodes.

>Tungsten
> rods are just a waste of money and tungsten.

Whatever you say ;-) For low to medium power levels this might be right,
but me and I believe most others think different about this. But as usual:
UMMV ;-)

best regards

Christoph Bohr