Improving the Ultrasonic Unit

The proprietor of Midnight Science decided to improve the RX2 design. Thissparker.jpg was great news! I volunteered to help with testing and some experimentation with component values. To help with this I needed a stable spark source. I constructed a spark gap using heavy electrodes mounted to large aluminum blocks that act as heat sinks.  I ended up running 1500 volts AC on this thing, with a 100,000 ohm current limiting resistor. You could really smell the ozone generated by this contraption!

The process started with modifications to the RX2 and progressed through several prototypes. The resulting RX3 can reliably hear the sparker at 100 to 105 feet in calm conditions. This is a considerable improvement over the stock RX2 which lost the signal at 35 feet from the spark.

Some of my power line noise problems had been fixed by the time the final RX3 was ready, but the prototypes had found noise at more than 60% of my RF noisy poles. This is a remarkable improvement over less than 20% with the RX2.

I regret to say I am still not happy with the dish. I am certain this thing loses several dB of performance due to shape irregularities. This is a subject I will be revisiting at a later date.

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