The earlier model VXR-7000 did use a 2SC3102 UHF transistor as it's PA which are now very hard to source.?
That design also had some problems where the capacitors on the output side of the transistor may explode and burn the PCB.
> S-AU93 module apparently 'cooked'.? Various datasheets suggest this is a 50-60w part
To follow up on what Andy wrote, I received fake modules from China recently ¨C the first bad batch of eBay parts in several years.? These were Toshiba? S-AV17¡¯s; 50-watt VHF modules, very common in mobile ham radios from yesteryear.? None of them came close to making rated power.? Upon closer inspection, it was obvious that the black plastic cap had been replaced, with the new cap sloppily glued in place.? The baseplate on the fake parts appears to have been dipped or electroplated poorly with a weird, easily-flaked-off, substance with paintbrush-like swirl marks.? The shape of the baseplate wasn¡¯t even the same as known-authentic parts; they could very well have been lower-power Mitsubishi brick ¡°pulls¡±.? If anyone wants to see pics of the real vs fake parts let me know.
As a suggestion for your S-AU93 replacement, look at Mitsubishi RA60H4047M1 (400-470 MHz) or RA60H3847M1 (380-470 MHz).? The package and lead dimensions are very close to the S-AU93, and the specs are comparable as far as drive level (50 mW nominal), gate/control voltage, etc.. There's a US seller on eBay that has the latter as pulls for $28.? I bought 20 (?) of them from him and all have worked perfectly.? Double-check the footprint to make sure it will mount and align in your VXR7000.
Oh, one thing to mention - there is a different between Mitsu bricks with an "M" vs "M1" suffix.? You usually don't want "M" - those have a recess in the baseplate; they are meant to be used with a gap-filling thermal pad.? M1 parts have a flat baseplate that mounts direct to the heatsink with the usual extremely-thin coating of thermal paste.
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? --- Jeff WN3A
