Before I reinvent the wheel, I thought I'd ask if this exists as a
commercial product or homebrew project. I've googled quite a bit
without success.
What I need is a screwdriver antenna controller that listens to CI-V and
commands a DC motor to a predetermined stored in memory rotation count.
The MFJ-1924, which I use to control a Tornado variable inductor on a
rotatable 80m dipole (reworked EF180C) does half the job in remembering
the turns count that the reed switch emits inside the inductor and has
10 memories that are manually preset for a match. However, the operation
is manual, I check my frequency, look at the list of remembered count
for that frequency (every 50KHz) and push the appropriate button 1 to 10
and wait for the motor to advance to that count. There is no transmit
lock-out such as on the SteppIR controllers to prevent transmitting into
a big mismatch condition.
The MFJ-1926 gets some of the other half done, as I understand the
manual. A high and low frequency limit is set for each band and it
listens to CI-V strings and sets the antenna drive count to a
predetermined count. It's not quite clear if there is any interpolation
of counts from high and low presets or if it is up to the operator to
fine tune the screwdriver from there. I don't have one, perhaps a
topbander who has one can clarify how it works.
I'm building a variable resonance 160m antenna to cover the whole band,
so while another 1924 will provide the basic control function, I'd
ultimately like to make both bands fully automatic (2 controllers would
be fine). Frequency and turns count would be entered manually at at
least 10 frequencies in the band by manually measuring swr. When a new
CI-V frequency is received the amp would be inhibited until the turns
are achieved . The motor drive, calibration, and monitoring should be
at least as capable as the MFJ boxes and state and frequency counts must
be saved thru power cycles.
I have to admit that a steppIR/THP amp/THP tuner/Pro3 have totally
spoiled me. I want it on 80 and 160!
Grant KZ1W
first post to TB by me
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