hope this helps with the cushcraft a3s trap reading on the dip meter


Check each trap to insure that the cover is tightly secured. The
cover is the 1-5/8" tubing between the two large black end caps.
Any movement of this cover will cause an intermittent VSWR
condition on the antenna. You may easily test for a loose cover
while the antenna is still assembled. Grasp the cover in one hand
and the trap tubing in the other hand, apply a moderate amount of
pressure first in a clockwise and then a counterclockwise direction
about the axis of the element. If the cover slips even a small
amount it will require tightening. Remove the black cap from the
trap on the side towards the boom of the antenna. A hex head screw
will then be visible underneath. Tighten the screw with an
appropriate screwdriver or nut driver. Be careful not to apply so
much force as to strip out the sheetmetal screw. If the hole is
already stripped, or gets stripped accidentally, it is an easy
matter to be fixed by substituting a #10 3/8" or 1/2" self-tapping
screw into the enlarged hole.

If all your traps pass the mechanical test and seem to be
installed properly, then a frequency check is in order. (The
traps should be marked before removal so that proper reassembly
is assured.)

Place a trap on an insulated surface (such as a large cardboard
box) and couple a dip oscillator to it as shown. Make sure to
couple it to the end of the trap that was closest to the boom,
the end of the trap that was self-tapping treads visible inside
the tubing. Insert the tip of the dip oscillator coil slightly
into the tubing. When a dip is found pull the oscillator coil
out of the end of the trap slightly and re-dip the oscillator.
Continue to pull the dip oscillator coil out of the tubing and
re-dip until you have the smallest perceptible dip. It should
be noted that the dip meter frequency is lower than the
operational frequency of the trap. This is caused because the
trap will load the dip oscillator and lower its frequency.

TRAP Oper Dip Osc
Freq. Freq.

TA 28.60 27.50
TB 21.50 20.39
TC 21.30 20.20
TD 28.00 27.00
TE 28.80 27.60
TL 24.90 24.15
TM 18.11 17.29
TN 21.30 20.20
TK 14.18 12.62

You should use the listed oscillator frequencies as a guide.
Temperature and humidity can have a +/- 100KHz effect on traps.
If the readings are within 200KHz of the listed amounts, do not
worry, the effect upon the assembled antenna will be minimal.
Shorted turns or other serious defects will cause wide shifts
from the norm. One or two megahertz is a definite indication
of a defective trap.