gevv
| | Tarih: 15.12.2006, 14:15 Mesaj konusu: Tonemeter | |
| While measuring antennas years ago, we found that it is difficult to point a large antenna
and watch a meter simultaneously. I eventually made a box which converted the meter
output into an audio tone whose frequency was proportional to the meter reading. This
allowed peaking by ear, listening for the highest pitch. It worked very well, for all except
a few tone-deaf individuals.
Last year, I was “snowflake” tuning a surplus microwave amplifier, sliding tiny bits of
metal around the circuit to retune it to 10 GHz. Here again, it was hard to watch the
meter while looking through a microscope to move the flakes. It occurred to me that the
audio tuning box might help – but I couldn’t find it. Since I have passed on the antenna
measuring fun and equipment on to others, the box probably went along. I continued
trying to tune the amplifier, but finally slipped while I was looking at the meter and let
the smoke out.
It was time to build a new audio tuning box. I found the schematic in an old notebook,
dated 1977. The integrated circuits I used are still available 25 years later, but are better
ones available now? Not really, unless we are trying to do something fancier, like a
computer interface. For a simple circuit, the old
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