Cecil Moore wrote:
Ian White GM3SEK wrote:
What kind of wire, what kind of insulation, and how much gap between
turns? It affects the self-capacitance.

Unfortunately, the spare (75 ohm) coax that I
have to experiment with came free from the local
TV cable company and is unmarked. It is ~0.26"
in diameter with a ~0.04" outer insulation. All
conductors are aluminum. There is an aluminum foil
wrapped around the foam insulation under the aluminum
braid. The choke is fairly close wound with approximately
3.5 turns per inch.

OK, that's close enough to several alternatives such as RG58.

I'd like to try that on the VNA, but here in the homeland of
porridge, oatmeal boxes are rectangular!

Do you have 2 liter plastic pop bottles available
there? I'm going to re-do the experiment with one
of those as a coil form. There's an endless supply
of those coil forms from the day care center next
door.

Ours spell "litre" differently but I guess they're the same - 95mm or
3.75in diameter? If plastic bottles from the USA are a different size,
I'll go fetch one from our local beach... you'd be amazed at what floats
across.


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek