Jerry Martes wrote:
In fact, I'd like to know more about why a
person (HAM type) would use the slab line
configuration in preference to coaxial....

One advantage of slab line is that when you
drop something like a set screw into the
line, it falls right on through. (Been there,
done that).

I've used the HP slab-line instrument and
obtained very good, repeatable results with
it.

Others have commented that the big advantage
is ease of fabrication, and I have to agree.
Cutting a slot in a water pipe seems like a
lot of trouble for minimum gain.

Another alternative might be a trough line.
This is a slab line with bottom side closed
off. The advantage this would provide is a
means of supporting the center conductor
by means of a longitudinal, dielectric strip
between it and the bottom plate of the line.
A long piece of Teflon fiberglass would be
ideal for this. The line dimensions would
have to be adjusted to maintain a 50-ohm Zo.

Anyway, it's an interesting project. Good
luck with it.

Jim, K7JEB
Glendale, AZ