Found this in my junk box today. This has been floating around in my junk box since like 1992. I forgot I even had it. I think I originally had the entire casing and heatsink that went with it.
Looks like a 2 x MRF475 linear amplifier with thermal tracking (via diode under board see bottom side pic) bias circuit. Though a resistor or Choke for the Bias Circuit appears to be missing.
What I would LIKE to do with it, is forever, I wanted to build a small low power compact amp that would perform well from at least 80-10 meters to go behind my Softrock RX/TX, which has only 1 watt max output. So I'd need a high gain amp. I built a single MRF455 amp and biased it all to hell at .7V and it works OK, but this looks like it would work better for my needs. Original Motorola Datasheet on this MRF475 (they both test good BTW on handy old Micronta neon bulb transistor tester) suggest that it will do around 15W with 1W input (per transistor) and also suggests that the gain is quite high in common emitter config down to 2.0Mhz.
Anyone have a complete one of these or a schematic of the original? Would I be way better off building it as a 2 x IRF520 unit?
Pics:
Looks like a 2 x MRF475 linear amplifier with thermal tracking (via diode under board see bottom side pic) bias circuit. Though a resistor or Choke for the Bias Circuit appears to be missing.
What I would LIKE to do with it, is forever, I wanted to build a small low power compact amp that would perform well from at least 80-10 meters to go behind my Softrock RX/TX, which has only 1 watt max output. So I'd need a high gain amp. I built a single MRF455 amp and biased it all to hell at .7V and it works OK, but this looks like it would work better for my needs. Original Motorola Datasheet on this MRF475 (they both test good BTW on handy old Micronta neon bulb transistor tester) suggest that it will do around 15W with 1W input (per transistor) and also suggests that the gain is quite high in common emitter config down to 2.0Mhz.
Anyone have a complete one of these or a schematic of the original? Would I be way better off building it as a 2 x IRF520 unit?
Pics:
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