My setup tunes to 900 kHz
Note: Use a 1/2" (13 mm) stretch on the spring to create a tuned
coil antenna. The spring has an light insulating coating between turns.
Century Extension Spring
(substitute
at your own risk)
C-253 9/16" x 16-1/2" x .054" (14.3 mm x 419.1 mm x 1.372 mm)
16 turns per inch (approx. 252 turns at a ½" I.D. diameter)
Purchase
at Amazon
The
un-stretched C-253 spring end coil end to end should be 15
5/8" or 15.625"
or 39.7cm
I insert a
1/4" wood square stick cut to size 16 1/8" or 16.125" or 41cm long. The ends press against
the inside of the double loop mounting rings.
After the stretch
it should be just over 16.125" or 41cm edge
to edge between the end loops.
The base of the
antenna is attached to a high current 3.3mh
High Q choke to earth ground.
There seems to be a 3/8" (10 mm) variation in spring lengths from different
vendors, always use the C-253. Add the 1/2" or 13mm stretch
and hope it works.
Link
- Plastic 3/4" or 5/8"
id 18" Sleeve to keep circulating
air off the sensitive spring/coil pitch antenna.
Arrived
in 4 day USPS
That
dangling choke mounts on the PCB. You
may want to use a 21" length acrylic tube, it looks the
nicest.
PVC
sprinkler pipe will also work but not as pretty as clear acrylic
pipe.
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