Unilab 10m FM conversion Transmitter PA mods - Revised Driver Stage

After a few cooler days I have been able to finish the driver stage. In place of the BLY32 there is now a two stage amplifier. It was all a bit of a squeeze but we managed to fabricate a PCB that would fit in the cut-out .

Schematic of replacement for BLY32 module

PCB of BLY32 replacement module before preparing to etch.

BLY32 replacement module installed

I made an error on the pcb layout which is why the collector of the 2SC1971 is floating. If you would like to see a revised circuit board as a pdf so you can build you're own please ask!

Using the 2SC1971 as a driver means we are limited to driving the final stage with around 6W. Which is enough for 100W from the radio if we have 13db of gain in the final transistor which I suspect we do have.

At present I am getting 40W out of the radio, current draw is around 5 amps. I think I have discovered why I am not getting 100W. It was to do with output matching. As built, the radio's output matching network is not as per the circuit diagram. It turns out the variable capacitors on my radio had a different pin-out with the result the matching network is different than I has assumed. I will alter my radio and let you know what happens.

Regards
Richard VK6TT