"R.van Trotsenburg" <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- Hi, I use the trick with the relay over the termister successful in my SB1000 amplifier already for a long time. As soon as the 12V from the power supply comes up it actuates the relay and shorts out the thermister. I my QRL we use this as well in large power supplies, to protect the mains if multiple units are switched on simultaneous. 73 Rien PA0TRT
Message text written by "Jim Shorney" >"Jim Shorney" <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- On Thu, 15 Dec 2005 10:03:59 -0500 (EST), [EMAIL PROTECTED] wrote: >My only concern with thermisters is they increase HV transformer primary >winding ESR and slop the HV regulation. At 50W load for a typical R-4 the >voltage drop by the thermister probably isn't much, but 400W load for the >AC-4 would probably reach the maximum permissible 10% voltage drop range >adding to frequency drift during key down. 100VAC is too low methinks ;-) > >I experimented with one of them for feeding my AC-4/T-4XB and the panel >lights dimmed enough to make me nervous with 80W PEP CW output. > >How much dimming effect on the panel lights do you notice with the part >you used? I may have one that isn't suited for that much current draw. There didn't seem to be any abnormal dimming, from what I could tell. I just used the twins in the 10 Meter contest and got good preformance without any apparent problems. If voltage drop is a concern, a small relay with an R/C time delay could be added to short out the limiter after it has done it's job. The upside to the relay method is that the limiter would return to cold and be ready to do it's job again if you have a momentary power interruption. OTOH, it can be argued that with line voltages being higher these days, a little extra voltage drop in the primary circuit may not be a bad thing. I was looking at some that were sized appropriatly for my L4B, but I haven't done the math and that project got put on the back burner. 73 Jim < ---------------------------------------------------------------------- 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 ----------------------------------------------------------------------
