This is my forum for telling the world
what's
keeping me busy these days.
This is the antenna tuner mounted on the wall in the utility room.
The variable capacitor on
the left is C1, a 500 pf E. F. Johnson transmitting variable I found at
a hamfest 25 years ago. The cap on the right is a 4 gang, 500 pf
variable out of a 1940's vintage shortwave radio. The roller inductor
is a 64 turn, silver plated, 100 microhenry job that I found on Ebay
for $35. Each of these devices is motor driven and has a pot attached
to it for position feedback. The motor drives on the 2 capacitors are
from Samsung ice makers, and the roller inductor drive is the loading
drive from a Panasonic VCR. The white block up on top is a 12 volt
gel-cell battery to supply motor starting current. A wall wart from an
answering machine keeps it charged. The little board on the upper right
is the motor selection and direction logic, and the larger board on the
left holds the motor drivers, relay drivers, and the 5 volt regulator
for the logic board. The perfboard below the motor drive board holds
the FET's that switch the active feedback pot to the remote wiring.
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Comments? Email me - jim (at) jimdaldry.com