All,

As with all shortwave projects, converter projects require substituting
currently-available coils for those recommended a couple decades back. Each
converter coil needs a comment or two. They all use magnet wire obtained from a
local TheShack store. The wire gauge should not be critical.

L1 and L2 have 29 turns each tapped at 6 turns wound on a 13-mm (0.5-inch)
diameter form. I cut the forms from a felt highlighting pen using a tubing
cutter. Don't try to cut a marker using a saw. It's not worth the mess.

L3 and L4 are 12 turns each on an Al = 75 HF toroid. Twist the wires together
before winding. Power-supply toroids don't work well. Otherwise, use your
favorite brand.

L5 is a TheShack 100 uH RF choke. It will need 10 to 25 turns removed to tune
up to 2,600 kHz--more turns removed if the output will be 3,500 through 4,000
kHz.

L6 is 10 turns wound over L5.

The converter has been in service converting 5-MHz WWV and 49-meter (6-MHz)
international broadcast to 1700-2400 kHz. I've been using crystals above the
input frequency—7,100 kHz for 5,000-kHz WWV reception and 8,030-kHz for 5,900
through 6,200-kHz international broadcast. A computer surplus 9,216-kHz crystal
should work for 40-meter (7,000 through 7,300 kHz) amateur radio reception. But
I haven't tried that yet.



Happy experimenting,

Steven

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