"Jim Shorney" <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- On Sat, 15 Dec 2007 17:44:33 -0500, Mike Bryce wrote:
>in the old supplies, the damage is caused by a "lack" of bias. So, if >there is a failure of the bias supply, i.e. it quits, how can you fix >that? > >the only way I could come up with would have been a system that >deprives the transformer of it's primary voltage, shutting down the >supply. It would have to default in the off position too, as you >would not want the supply to cycle on, find the missing bias, then >shut down, the power up, find the missing bias supply, shut down and >on and on. Here's my thinking: a simple transistor/relay circuit powered by the heater supply. The transistor is biased off by the negative BIAS supply voltage. BIAS goes away, transistor turns on. Transistor pulls relay that removes high voltage from the radio. Or crowbars the high voltage, pick your poison. Design in a threshold so that is fires if the BIAS supply output drops lower than XX volts. You could even have it light a big red light labeled "NO BIAS, DUMMY!".... I'd do it, but I've got to get back to that HyGain 3750 that's vexing me today. 73 -Jim -- Jim Shorney -->.<--Put complaints in this box jshorney (at) inebraska.com Ham Radio NU0C Lincoln, NE, USA EN10ps http://incolor.inetnebr.com/jshorney/ ---------------------------------------------------------------------- Submissions: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net ----------------------------------------------------------------------
