Hi Hugh, just a thought, but old fashioned telephone engineers used to use
coils for loading lines (the ubiquitous 88mH comes from this era) For
outside use they were often sealed in an iron pot filled with wax (or pitch)
to keep the water out. I seem to remember comments about putting "pots" in
the line, but this is really before my time and probably dates back to a
long time before ferrite was available.  I was not on that side anyway.
Maybe a real telephone engineer might have some thoughts. Generally the
so-called "pot" cores totally enclose the bobbin (like a "pot"??), though
this is not quite the case with the RM design cores which are "X" shaped.

My 1972 Mullard Passive Components catalogue shows series of pictures that
distinguish RM cores, from Pot cores, which totally enclose the bobbin. I
suspect the "X" cores allow the bobbin to be wound and the coil ends
terminated on the pins before the enclosing ferrite was installed. This
probably made for a better production flow. The pot core is a bit more
fiddly to deal with as it the bobbin must be installed with flying leads
which then need to be soldered to the carrier pins.

Of course the Navy might have a different explanation, but then they used
to define their capacitance in "jars" and measure it in centimetres !!

Cheers de Alan G3NYK
[email protected]

----- Original Message -----
From: "Hugh M0WYE" <[email protected]>
To: <[email protected]>
Sent: 22 September 2003 16:30
Subject: LF: Pot cores

Hi Group
While pondering a filter design and playing with a pot core type

inductor...

RM6 / RM10 etc.
I wondered: "Why is it called a pot core - it doesn't look much like a pot
?"
Anyone know how the pot-core got it's name ?
Silly, I know, but one does like to know these things ...
73
Hugh M0WYE