so ive been working on this thing for about 3 months now and i finally got it oscillating and putting out what seems like a reasonable signal. started from a design i found in an old ARRL handbook, the 1987 edition i think, and modified it a bit based on some stuff i read on eham.

the VFO stage seems stable enough, drifts maybe a few hundred hz for the first 10 minutes then settles down which i can live with. the problem im running into is the PA stage — im using a 2SC1969 and at 12v im only getting about 3 watts into a dummy load. the design should theoretically do 8-10w and ive checked the bias point twice now. collector current at idle is sitting around 60ma which feels right but maybe isnt.

the lowpass filter is 7-element chebyshev, wound my own toroids, and i checked the SWR going into the dummy load which is flat so i dont think its a matching issue. wondering if anyone has built with this transistor and had similar output issues. could it be a bad transistor, i ordered like 5 of them off ebay and they might be counterfeit. also the pi network tuning is kind of a mystery to me still, i calculated the values but not sure i got the component Q right.

the ebay 2SC1969s are almost definitely fakes, thats just reality at this point. ive burned through probably a dozen of them on various projects and maybe half were pulling anything close to spec. try sourcing from RF Parts or even Mouser if they have stock, the genuine ones behave completely differently. i had one project where i was scratching my head for weeks and swapped to a verified transistor and boom, right where i expected it.

also worth checking your drive level into the PA — if your buffer stage isnt putting out enough to drive the base properly you'll just be leaving power on the table no matter how good the transistor is. what are you seeing at the PA input with a scope?

yeah counterfeit parts from ebay are a real gamble especially for RF transistors, been there. but also double check your toroid winding — if you miscounted turns even by one or two on the output transformer that can kill your efficiency pretty bad. the pi network Q thing is worth spending time on, a lot of homebrew designs assume a Q of around 10-12 and if youre way off that the output just kinda... doesnt happen. what core material did you use for the toroids?