The first job here was to drill a bit of PCB stock, to mount the BNC socket on. This was deliberately drilled a little too small, allowing for creating a keying flat during filing it out to size.
With the PCB drilled and roughly cut to size, the BNC panel socket was fitted. The corners were then cut off and the PCB filed until circular.
The circular PCB is single sided, and so is fitted with the copper facing the socket. This is the 'bottom' of the antenna.
Using my 150W iron, the PCB was tinned, and the antenna elements soldered on. Each was cut a little long, to ensure that there was some play in the dimensions.
With all the elements soldered, a marker for 68mm was made on the jig block, and each element measured and trimmed. The BNC to SMA patch-lead was connected, and the ground-plane elements bent to shape. That done, the coax patch-lead was threaded through the antenna mount on the radomes internal equipment board, and the antenna secured in place with hot-melt glue.
A test fit was made to ensure that the driven element of the antenna would fit cleanly into the spire of the radome.The next stage of this project is to size up the equipment board and drill it for mounting pillars to attach the electronics.
I now have the BOI-33 G-M tubes, and most of the necessary parts for the Geiger counter. Ive ordered the correct sized fuse clips to attach to the tubes (6.3mm rather than the common 5mm), these should be with me by the weekend.
Tomorrow, I am going to bread-board a 3V to 400V zener regulated flyback HV generator, for powering these tubes. I've some 100V zeners on order, which will make regulating these circuits a bit easier, as only four would be needed! The prototype tomorrow will use the only zeners I have at the moment in 'high' voltages, so will be a string of eight 47V devices, plus one 24V unit! I could probably get away with fewer if I took the feedback from after the first multiplier, but the regulation will be that bit poorer. I might try both and see how they do.
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