Magnum 2000 resistor repair.

[c316buckeye]

had to look inside.. mrf455, straight 4. i was told it was a 2 pill and it has a magnum 4000 sticker looks to have been peeled off and says magnum 2000. i regularly have 45 minute conversations with the qt80 or kpo dx5000 as a driver (power almost all the way down, 60% mic gain). the mini fans get kicked on the second i start a qso, and the unit never sees 100°. swings 150 briefly, and i keep it well under that because the power supply meter is kept under 75% of it's potential. i keep a real tight eye on the draw and temps, and everything is loaded with fans.

 

[doffo]

had to look inside.. mrf455, straight 4. i was told it was a 2 pill and it has a magnum 4000 sticker looks to have been peeled off and says magnum 2000. i regularly have 45 minute conversations with the qt80 or kpo dx5000 as a driver (power almost all the way down, 60% mic gain). the mini fans get kicked on the second i start a qso, and the unit never sees 100°. swings 150 briefly, and i keep it well under that because the power supply meter is kept under 75% of it's potential. i keep a real tight eye on the draw and temps, and everything is loaded with fans. View attachment 75451

Pretty neat you also just have it set to Medium. My 2 pill Magnum 2000 I just keep it at medium. with yours having the four MRF455, its for sure doing better.

****Ooops, I mean my Palomar Skipper. The Magnum 2000 has the same 2 pills/transistors inside. Magnum 2000 I will slowly work on over the course of time lol.

 

[c316buckeye]

i like to try to keep stuff under 50%.. i need to get a quiet switching pwr supply that can take the job instead of that 20A pyramid getting worked over. what are you seeing on the 2000 with what drive numbers? any 2 pill likely generates the same S unit on the opposite end of the signal, so i never got worked up about 2290 vs 2789 vs 455 etc

 

[doffo]

i like to try to keep stuff under 50%.. i need to get a quiet switching pwr supply that can take the job instead of that 20A pyramid getting worked over. what are you seeing on the 2000 with what drive numbers? any 2 pill likely generates the same S unit on the opposite end of the signal, so i never got worked up about 2290 vs 2789 vs 455 etc

I dont have the watt meter hooked up, but when I did, it was doing well over 200+ PEP when you set it on high. Medium its doing 140ish? This is just throwing 10 watts SSB at it. Even on Medium, its drawing around 18 amps. High its for sure draining 20 amps.

 

[c316buckeye]

yup. that's why i don't know what it can do yet. be over drawing p/s. megawatt 33amp on the way will cure that, i guess. these magnums are happy. this poor thing has probably seen over 2hrs/wk of key time on ssb for the last 3 months and loves it.

 

[doffo]

yup. that's why i don't know what it can do yet. be over drawing p/s. megawatt 33amp on the way will cure that, i guess. these magnums are happy. this poor thing has probably seen over 2hrs/wk of key time on ssb for the last 3 months and loves it.

I did went ahead and bought some 33 ohm resistors and 100 ohm resistors to replace them. Also some screws/lock washers. Probably all be here in a week. I think what ultimately happened to the amp is that someone used it with a very small power supply. The 20 amp fuse has a burnt color/bend on it lol. So on top of driving the amp too hard, the amp was making a crap ton of heat from the lack of amperage being supplied to it. Sucks that those Toshiba pills probably got the beating of their lifetime.... Surprised it was making any kind of power now. Hope after the new screws, new fuse, and new resistors that the power output is ok.