[Boatanchors] QEX Dec 1988 Article

[McDonald, J Douglas]

...  It’s
too bad that 88/44/22 mH coils have become so seemingly scarce. ...

Its not hard to make your own, if you don't mind them being
a bit larger than the originals.  The large toroid cores are readily available
and being large, require fewer turns, and make it easier to get the bobbin through.

I can look up the specs of the cores I used. They are expensive but cheaper
than ePay prices for the old original these days.

I've made medium impedance (500-5000 ohms) audio filters
with excellent response for CW with these, similar to the audio filter
in the R-390A, and used them with good effect with my SX-88,
NC-400, and BC-453.

I tried cores the size of the original 88 mH ones and gave up from bobbin frustration.

Doug McDonald