Hi Jim,I don't think it's a good idea to mount the rectifiers inside the tank. It's definetly not necessary to imerse them in oil neither for insulation nor cooling purposes. Another reason is: Maybe you will kill some rectifiers probably during some initial tests so do you really want to pull out the transformer everytime just for replacing dead diodes?
Regards, Stefan----- Original Message ----- From: "Jim Mora" <wavetuner@xxxxxxxxx>
To: "'Tesla Coil Mailing List'" <tesla@xxxxxxxxxx> Sent: Friday, August 22, 2014 6:54 AM Subject: [TCML] Submerged diode strings hold off distance (transfomer oil)
Hello Group, Since I ordered and tested my Raytheon transformer fluid with a new Dexsil 40ppm test kit (available Forestry Supplies), I was pleased and bit surprised that it is well below the 40ppm PCB limit, in fact near the deepest purple on the lowest end of the test kit scale. It must have beenmaintained for duty and flushed several cycles as was evident when I openedit. It was military and under tagged FAA auspice after all. Therefore, I have reconsidered my design a bit to mount the rectifiersinside the tank. I removed the tall 12" horns for more space. And I seem to have ample room to mount my 6 pulse diodes strings recognizing there will besix pulse 12KV dc + to - to hold off at the ends. The strings (3) will be mounted horizontally as a stack and spaced to hold off the stress ~ 5KVac(H1,2,3 will go directly to the rectifiers at the isolated centers) and theends (+,- 11KV) to any target. All 3 stacks will be joined at the ends forplus and minus 6 pulse DC. Doing this frees up my three HV horns on the top.One will connect to negative the middle horn will connect to the internalpositive and deque diode junction. And the other side the farthest one will be dequed downstream positive to go to the external Charge Inductor. I willpaint the base clamps Black, Yellow, and Red. Black is misleading as it is well below ground potential (2 HV leads will exit). I will probably ground the inductor tank and transformer together and may use 2 x-ray cables coax case grounded at the transformer and strip 12" or so off out at the sparkgap. This has been an ongoing debate on the list unless it has been resolvedin my absence. This gives me the option to experiment on top with different + to adjacentminus storage capacitance (stiffening if needed) and ripple suppression anda serious reminder to discharge a lethal, hidden energy source (it would have bleeder but time is an issue after T1). Hopefully such a cap will not be needed, but I like this external simple freedom of selection. Having said all that, and if you stayed with me (thank you), how far apart should the stacks be spaced to prevent flashover, and from other targetslike the HV coils and grounded case parts. I would mount them equal distancein the center of the open space. I am more curious about the diode stackspacing. I don't have a lot of experience with real transformer oil and itsdielectric strength.Before the transformer reconfiguration there was 24KV for Raytheon engineersto contend with and it was crowded in there! Thanks Much, Jim Mora Ha ha, I am beginning to wish I sold this as a serious retro horror movie prop or to the steam punk affectionaire. I do have (7) NOS JAN 8020 rectifiers in original packing (40KV peak inverse) and vintage EF Johnsonssockets that will be for sale. The filaments are thoriated tungsten and glow pure white and instant on. Definitely old Frankenstein stuff! Those old >12"white ceramic horns and bases will be on the block too as will the hefty highly isolated 5V, 36 amp Filament transformer and maybe the 24KV 150H filter choke. It has been interesting working on something older than I amin great condition. This kind of device lends itself pretty well to EMP and was old school nuclear hardening. Forget about modern cars! It would be cockroaches and old diesel trucks still going ;-^) _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxhttp://www.pupman.com/mailman/listinfo/tesla
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