> "Bob M." <[EMAIL PROTECTED]> wrote: > Well, I know that the transformer makes heat all by > itself, but in the repeater cabinet, a fan is blowing > directly on the back of the supply and I've never had > anything get hot inside in over 5 years of operation > (except for the MaxTrac exciter running at 6 watts, > but the fan keeps it cool too).
Even with the fan... if you're pulling 25 amps from the supply the heat sinks will get warm.... real warm. The fan at best can only keep it from getting real hot. So hot you couldn't keep your hand on the heat sink metal. > I also load-tested the supply that's currently > running, with a pair of 1 ohm resistors in parallel. > They got really hot after several minutes while the > supply itself stayed ice cold. How about 45 minutes in operation at 25 amps load? Several minutes doesn't really cut the mustard. > I did discover that the supplies don't like being > powered up with a 1/2 ohm load across the output. I > only got 5V/10A; I presume that was a foldback of some > kind. When I disconnected the load, everything went > right back to 14V. With the supply running, the only > thing that changed when I reconnected the load was the > ammeter went from 0 to 28. The voltage at the output > terminals only dropped a few dozen millivolts. > Bob M. The astron supply regulator design does not power up well into high current demand. The variable "vls" supply is even more sluggish. There are 2 step start methods used by some people to deal with this "design quirk". s.
