Please treat the transformer/capacitor from a microwave oven with extreme respect. The energy from that system is most unforgiving and would be instantly fatal in many scenarios.
Even during the ~8 years since it's been out of service, I haven't bothered to take a second look inside the power section.
I built my HW-101 later that year. And got rid of the ARC-5 transmitter and old Hallicrafter receiver I had been using.
I built the power supply for the HW-101 because I couldn't afford to buy the one heathkit provided.
That transformer was given to me by an Elmer. I had to figure out primaries (yes, plural) and secondaries.
Got heater, B- and all those special voltages out of it, rectified, and smooth as a kitten. Life lesson in inductance and capacitance.
I've been playing with 'lektrikity for a long, long time.
What I talk my brother-in-laws into doing is my business. ;)
/johnny