[GreenKeys] 88 mh toroids

[Jeffrey Angus]

On 6/17/2011 8:37 PM, Jim Haynes wrote:
> Before 88 mh toroids were discovered by hams there
> were some T.U. designs that used TV width coils -
> slug tuned coils.
I remember playing with both in the early-mid '70s. I'd built an
experimental TU using a design from the GE SCR manual using
an SCR as a commutation switch to control the selector magnet.

Of course, around the same time, I'd acquired a twin-rack bay
full of multiplexed TTY TX and RX gear to gut for parts. ;-)
AN/FCC-3 if I remember right.
> AT&T had developed Permalloy, a very high permeability
> magnetic alloy.  They manufactured a cable for W.U.
> in which the center conductor was wrapped in a thin
> Permalloy tape, so that the cable was continuously
> loaded throughout its length.
What amazes me the most about a lot of this technology, was
how they came up with it using pencils for a calculator.

That and a LOT of hard core empirical trial and error procedures.

Jeff-1.0
wa6fwi