There is currently a thread on coax antenna traps.

In this thread, reference was made to the coax trap article by
O'Neil N3GO.

"Trapping the Mysteries of Trapped Antennas"

I have some stuff in my old antenna scrapbook that supplies a
follow-up/correction to O'Neils article. Evidentally there were a
couple of errors in the article, including an error in the actual OD of
the coil form used versus what was printed in the article. The
follow-up/correction is published on page 8 of "Ham Radio"
magazine February 1982.

I have further info regarding magazine articles that were published
pertaining to coax traps.

Larry East, W1HUE published a full-length article in QST "Antenna
Trap Design Using a Home Computer". This article DOES cover coax
traps.
Unfortunately, I don't know exactly when it was published, tho I do
know that it was later than May, 1986. A handwritten note on this
paper says "ARRL-supplied disk filename is EAST.BAS"

In June 1984 QST "Strays" column, there is a correction, relating
to some previous coax trap article in QST.

In May 1981 QST, Robert Johns, W3JIP has full-length
article......"Coaxial cable Antenna Traps"

In Dec. 1984 QST there is full-length article by Robert Sommer
N4UU......"Optimizing Coaxial cable Traps"

In March 1984 QST is a letter....possibly Technical
Correspondence.....captioned "Coax Antenna Trap Design". Written
by Frank Noble W3MT. Noble presents some math and formulas, etc.

In Aug 1985 QST in Tech Correspondence are 2 articles, titled
"Coaxial Cable Traps" .

In Dec 1980 Ham Radio Horizons, Robert Johns W3JIP has full-length
article "Three band Trap Vertical"......in which he builds and uses
coax traps for a vertical.

In Nov 1983 QST Robert Johns W3JIP has full-length article dealing with
coax traps, titled "Dual Freq. Antenna Traps".

In Aug 1984 of CQ magazine is a full-length article by Cornelio Nouel
KG5b......."Exploring the Vagaries of Traps"......talks of coax
traps.

Lee Carkenord KA0FPJ