Bridge in the Plate circuit

Nov 10, 2008 0 Replies

Has any one ever inserted a SWR bridge in the plate circuit going to the tank so that SWR could be monitored to prevent disaster while ramping up R.F. power? This is a 100Khz OSC/AMP circuit. The tube is rated for 375K watts but we don't use that much of it .



Just looking for a tempory/Permanet solution to prevent arcing when the load is defective.



I was going to pass the plate electrode lead (#6 wire) through a donut that composes a SWR bridge (potential type bridge) so that standing waves could be measured while ramping up the power.



The OSC is a basic hot cathode tube using a isolated inductor as a feed back with cap in series to set the OSC freq into the grid. The plate/anode is connected to the R.F. transformer primary side.



This system uses B- and is feed at the cathode, so the PRIM R.F. transformer leads, come from the Plate and go to ground. We have a spark gap set for 1/2 " at the moment and when something is going wrong on the load side, which is inside a pressured sealed SF6 vessel, it some times arc, like currently. We are trying to come up with a way to monitor this issue so that the system can be alarmed while ramping up and shut down. The Plate Lead we can get to easily while the primary side-R.F. xformers are inside of the pressured vessel.



Thanks for any comments.


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