Ray and QRP-L gang,
In response to a private inquiry I measured the characteristics and
physical dimesions of the plug-in coil set of my old Knight Kit Ocean
Hopper as best I could. (nope, I don't have the Hopper, just the coils)
Here's a public post after the completion of the measurements on the
Ocean Hopper coil set.
Frequency range: 15.5 - 35 MHz
primary winding: 3 1/8 turns, spaced to occupy 1" on the
form
appears to be # 20 wire
measured about 0.5 uH on LCR meter
secondary winding: 3 turns of same size wire, INTERWOUND
w/primary
Frequency range: 7.0 - 17.5 MHz
primary winding: 8 3/4 turns, spacewound, occupying
0.81" on the form
appears to be # 20 wire
measured about 2.8 uH on LCR meter
secondary winding: 4 (just shy of 4 actually) turns of
same size wire, closewound
1/4" space between windings - secondary below the primary
Frequency range: 2.9 - 7.3 MHz
primary winding: 23 3/4 turns occupying 0.82"
closewound
appears to be # 20 wire (using 0.021" [.82" /
24 t] as wire diameter)
measured about 17 uH on LCR meter
secondary winding: 4 (just shy of 4 actually) turns of
same size wire, closewound
3/16" space between windings - secondary below the primary
Frequency range: 1.65 - 4.1 MHz
primary winding: 42 3/4 turns occupying 0.93"
closewound
appears to be # 24 wire (using 0.021" [.93" /
42.5 t] as wire diameter)
measured about 50 uH on LCR meter
secondary winding: not quite 9 turns (because of
connections) of same size wire, closewound
1/4" space between windings - secondary below the primary
Frequency range: 530 - 1900 kHz
primary winding: 78 turns, closewound, occupying 1.17"
on the form
appears to be # 28 wire
measured about 150 uH on LCR meter
secondary winding: 15 turns of same size wire, closewound
0.2" space between windings - secondary below the primary
a jumper is included between the 12 o'clock and 3 o'clock pins (see
below)
(I guess to switch in more capacitance)
Frequency range: 165 - 540 kHz
primary winding: a multi-layer winding of what appears to
be #30 wire
winding length only about 1/4 "
measured about 1525 uH on LCR meter
secondary winding: 36 turns of #28 wire, closewound, about
55 uH
1/4" space between windings - secondary below the primary
jumper from 12 o'clock to 3 o'clock pin (see below) as with the above
coil
form outer diameter for all of the above is 1.25" (polystyrene)
connections for all of the above (except 165-540 and 530-1900 kHz):
looking at the base of the form from below (pin side) with the "lonely"
pin at 12 o'clock
top of primary to 12 o'clock
bottom of primary to 9 o'clock
top of secondary to 7 o'clock
bottom of secondary to 5 o'clock
no connection to 3 o'clock
Disclaimer: no claims to ultimate absolute accuracy, but should be
acceptably close for experimenting should anyone be wishing to revive an
old Hopper.
73 and Happy Hopping,
Jim N5IB
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