[Prev][Next][Index][Thread]

of Hamfests, and stuff that got away...




This weekend (staring Fri afternoon, thru Saturday) 'the big' New England
Hamfest/flea, at Rochester, NH will be on.  (I'll try to find a tesla T to
wear, I'll be gone by noon Sattiday).

As to 'things getting scrapped, i got, too late to act on, or share, a flyer
for the 'dispersal auction' of the equipment from the now defunct Super
Conducting Super Collider....  THAT would have been fun.

======================

A small comment on the way components work in the real world.  I suspect
lots of folk know this, but it may be helpful to make it explicit:

	Things Change With Frequency.

(Thats too broad to be useful so let me give an example.)

Take a paper/oil cap, say one designed for power factor correction.  It not
only gets lossy as frequency goes up, at some point it STOPS being a cap.

It becomes an inductor.  Really.  Same is true of all caps (and all components,
to some extent.  The exact freq varies with the design of the cap (or whatever).
I have put a cap, that i was using for RF bypass, on a tracking gen/spectrum
analyser rig and watched it resonate, all by itself, at 30 MHz or so.  (That
was a smallish cap, on the order .001 uF.  I was using it below 30 MHz,
so that was ok...)

A standard 'trick', if wide band performance is important, is to pu a low value
cap in parallel with a high value cap.  That way, as the high value cap gets
lossy/up capacitive, the low value cap will still look like a cap.  The combo
will still resonate SOMEWHERE, but at a higher freq.) 

(If that collection of tesal papere IS for sale, lets start a collection of
cash....)

	regards
	dwp