i dont know about that mfj unit but i have a home built crystal
converter with 8 switchable crystal slots and a variable preselector
front end. i can cover several sw bands and it is damn nice even if i do
say so myself! it works as well as the am section of the car radio
allows it to. the car radio is the most limiting factor and an am radio
is not really designed to the specs needed for great reception under sw
conditions. for the $100 price of the mfj converter one could buy a
cheap portable sw radio that will blow the socks off of any am/converter
combo. almost any sw portable will easily outshine the converter and you
wont need the calculator and the degree in calculus to tell what
frequency you are on. my setup for dumptruck swl'ing is a ratshack
dx399(sangean ats 606) and a long base loaded cb whip antenna. it works
great! the converter/am radio combo is barely adequate by comparison.
mount the portable with velcro, add a fm link to your car radio for loud
speaker volume and a mag mount cb antenna on the roof and you have spent
about the $100 that the converter cost but with much better reception
and a few more sw bands. i am not kidding, almost ANY cheap portable
will do better than the am converter combo!