After about 3 weeks, rectifier tube 36AM3 for RCA model 1-RD-45 clock radio arrived from Antique Electronic Supply. It is amazing how expensive it is to import these old radio parts to Brazil. The final cost is about 4.8 times the cost of the part at AES. Besides international S&H, that is normaly high, tax in Brazil is paid over the total invoice. It means, over products, S&H, and carrier, as well...Ufahhhh!!!

After replacing 36AM3 tube, set only works when I place my hand near/on the loop antenna windings. Since the tuned station gets somewhat louder, the problem may be the tuning alignment of the loop antenna. First I'll check tubes again and then check and adjust the trimmer on the tuning capacitor. Other possibilities: open loop antenna winding, bad IF transformer, or some bad component of the detector/pre-amplifier stage.