The HV input filter… Input filter Mk1, on the left is my adjustable safety gap with the center electrode grounded, top and bottom are two 470 ohm 30W wirewound resistors in series on each 5kV leg, the small blue blobs are 1000pF 3kV caps in a mini MMC setup giving … Continue reading…
The mighty GU-81M Tube. The picture is deceiving, it measures 260mm tall and weighs in at 1kg ! It’s original use was for Russian military radio transmitters, 700w of pure high frequency electrical mayhem ! It required some repairs before use, these can be seen here. Before connecting the tube … Continue reading…
The tank capacitor… Front view, 70 x 0.47uf 1500v caps in five strings of 14 to give a value of 16.7nf at 21,000v. Looks like a chopping board, but really it’s a high voltage circuit board ! Back view, 70 x 10M 0.5W hv resistors to discharge the possibly lethal … Continue reading…
This will be my second coil, when I finish building it ! The vacuum tube coil uses a very large Russian radio transmitter valve in place of the spark gap in the standard coil. It runs as a self controlled oscillator, continually charging and discharging the tank capacitor into the … Continue reading…
The primary and secondary coils… The freshly wound secondary coil. The coil former is 110mm pvc soil pipe, dried, sanded, varnished, sanded, wound and varnished three more times. As usual, the winding jig is made up of junk box stuff, the motor was a little too slow, at only 9rpm, … Continue reading…
It’s usually best to start at the bottom… The base assembly prior to varnishing etc. The coil supports are made from HDPE (chopping boards) and were cut on a table saw which worked quite well. I fixed them to the MDF base using a hot-melt glue gun. The grey socket … Continue reading…