On Mon, 19 Jan 2009 08:10:07 -0800 (PST), JIMMIE
wrote:

Jeff, Apparently TV matching transformers used to be air core and
their use was quite common on 6 and 2 meter antennas.

Not on any 2m or 6m antenna I've seen or build. Most of what I've
seen used T-match, hair-pin match, gamma match, or something similar.
For the vertical collinears, I used a tapped coil. If I wanted lots
of bandwidth, perhaps a ferrite core might be useful, but for single
VHF band antennas, it's a lossy waste.

I knew the ones
built into the old tuners were but I hadnt thought the old line
transformers also being air core.

The over-simplified idea behind the ferrite (or powdered iron for HF)
cores is to increase the inductance of the windings so the xformer
works at lower frequencies. At VHF and UHF frequencies, the core
mostly disappears and you're relying totally on the coupling between
the bifilar windings.

They were per some of the locals on
2m repeater. If they aare the ones I am thinking of(big fat ones) I
have a few at home.


Jimmie
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558