[Lowfer] cores

[W5JGV]

> How can you tell anything about 'em when you rip 'em out of a
> piece of
> junk?  The few I've bought new were color coded for material
> type.  Is
> this std across mfgs?  Or are the ones you find in junk like
> supplies ever
> marked like that?

Most of the ones used for RF chokes - such as on the video cable or the
AC power leads - will ne a #43 material.  The transformer may be a #2
material or powdered iron.  While I was testing my 400 watt 166.5 rig I
took one of the switching transformers and used it to match the rig to
the test load.  It handled 400 watts FB with only slight heating.  Most
of the computer power supplies I have worked on usually use a switching
frequency of between 75-180 KC, square wave.  Since the square waves
look very clean, I suspect the cores may be usable to higher
frequencies.  Be aware that most of these cores are double "E"
construction, and are cemented together with magnetic epoxy.  They're
difficult to separate without damage.  I usually carefully hacksaw the
windings off and thread new wire through the core windows.
73,

Ralph   W5JGV - WC2XSR/13