Hi Chris,
I took a separate floating power supply to build this circuit, a simple
transformer (10VA), a bridge rectifier, electrolyt capacitors, voltage
regulators, you know, the traditional stuff :-) You could decouple the
ground of the phase meter to the coax screen by a large C. But i think
is is worth to build a separate power supply. I personally prefer to
spend a few parts more just to avoid eventual EMC problems at high power
levels, you know...
73, Stefan
Am 20.11.2015 23:36, schrieb Chris Wilson:
Hello DK7FC,
Thursday, October 29, 2015
I have breadboarded the motor drive circuit and tested it with 2 one
and a half volt cells centre tapped and 1k pot to simulate the phase
change input. The drive motor works fine, and lowering the voltage to
say 7V it moves the variometer REALLY slowly. I am now about to build the
phase meter part of the antenna circuit. Do I need to isolate the
phase meter ground with say a 470pF parallelled with a 0.1uF to true ground?
Thanks.
Hi Chris,
Am 29.10.2015 21:26, schrieb Chris Wilson:
[...] albeit my loading coil needs manual
tweaking to move to the right part of the band. Not sure of the best
way to remote tune it, it would be nice to have the ability to move
about the band without running outside in the dark. I may start a
thread about what alternatives there are, thanks again Erwin
I'm using a motor driven variometer which uses the phase meter circuit
of the M0BMU LF tuning meter. It is working well on LF, where my antenna
resonance is so sharp that i have to re-tune when doing QSY by 7 Hz.
See:
https://dl.dropboxusercontent.com/u/19882028/LF/LFtunemeter.pdf
https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC%20Automatic_variometer_tuner%20.jpg
https://dl.dropboxusercontent.com/u/19882028/LF/automatic_variometer_board.jpg
https://dl.dropboxusercontent.com/u/19882028/LF/LF_variometer_drive_engine_arrangement.jpg
https://dl.dropboxusercontent.com/u/19882028/LF/phase_meter.jpg
2011 was a nice LF year for me!! :-)
73, Stefan
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