"Lee Bahr" <[EMAIL PROTECTED]> made an utterence to the drakelist gang ---------------------------------------------------------------------- One more thing to look at when the resistor blows! Many years ago I had a 3-500Z short and take out the resistor in my L4B. I called Drake and they told me to be sure and check the pi-wound RF chokes at the base of the tubes. They said they "COLLAPSE" when a tube shorts. I looked the chokes over and they looked good. I then replaced both tubes and the resistor and fired up the amp. POW! the resistor blew again. I called Drake and they told me to change the pi choke or chokes. They sent them to me and I replaced them and the resistor fuse again. I then fired up the amp with the new tubes and never had another problem. I called Drake about this and they told me my choke had "collapsed" internally when it drew too much current even though it looked perfectly fine on the outside with no burned wires or black carbon marks. Each of the wires on the choke looked good but they must have melted and shorted way down inside the pies. I measured the removed chokes from the amp with a ohmmeter and indeed one choke had less resistance then the other one. This was the choke in line with the bad tube. Apparently Drake saw a lot of pi RF chokes go bad when 3-500Zs shorted to tell me this before I even tried to repair my amp!
One side note. The tube that shorted never did give me a short indication on an ohmmeter. It apparently had a saged element and would flash to ground only with high voltage applied to the tube. Lee, w0vt ---------------------------------------------------------------------- On Behalf of "Lee Bahr" <[EMAIL PROTECTED]> Submissions: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ ----------------------------------------------------------------------
