I am using the old firecracker (for the serial interface) and talk to it through a USB / parallel device.
The transmission comes from a small half loop coil which generates a circular polarized signal. This is
not optimum for the typical TM751 which uses a linear antenna. My firecracker mounts onto a box
which contains the USB interface. I added an external PC ground plane and connected a short vertical
antenna to the ground plane through a small 3 turn coil. This coil is situated adjacent to the internal half
loop. This antenna then acts as a converter from circular to linear polarization.
Because the signal is a transient one I have not been able to come up with a measurement on signal
strength but I have observed that the signal can now reach to the farthest corners of my house, a very definite
improvement. It also reaches out beyond the pool area. I hope that this is helpful.
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Topic: Improving the range of the firecracker. (Read 8468 times)