Behold, qrk signalled from keyed 4-1000A filament:

On Wed, 17 Mar 2004 12:03:06 +0000, Paul Burridge
wrote:

Hi,

They look worryingly inductive on visual inspection (there are metal
foils rolled up in thar by the look of it.) And yet the CPC catalogue
says that their properties make them ideal for use in filters. Has
anyone any remarks (favourable or otherwise) to make about the use of
this type of cap in filter apps?

p.

They're great for LC filters. If you choose your ferrite right, you can
have a pretty stable filter over temperature.

Air-core my good man, air-core ;-)

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca