I have the BC filter for the MFJ259... Never could make heads or tails
of the so called 'instructions'...
I find that using EZNEC for getting initial element sizes and resonant
frequencies, then using a grid dip meter followed by a transmitter and
an RF current meter for final tuning has always worked for me...
I do use the MFJ259 quite a lot, but for my 80 and 160 arrays the
voltages from rectified BC getting into the analyzer often screws it
up... My best time is middle of the day when there is less propagation
of BC signals - usually that is when I am at the office, however
sigh...

denny / k8do