[Hallicrafters] Halli SX-101A advice

[howard holden]

A comment on the SX-101A saga, and a question for anyone familiar with the A series.

Replaced the power supply and audio cathode bypass caps, radio powered up fine, but no signals. With AF and RF gain full up, only some light microphonics. Noticed the 12BY7A was cold. Popped in a new one, it too was cold. Checked the schematic, and noted that the 12BY7A is the tube which is kept lit all the time along with the heating resistor.  No filament voltage at the tube, none at the separate transformer used for this. Thought the transformer might be bad, but found a completely unattached connection where the fuse for that transformer picks up 120VAC. The wire was just laying there. No sign of it ever actually having been soldered. It apparently was never properly soldered at the factory some 50 years or so ago, but had been laying well enough to make contact, until we moved in August. Connection reattached, receiver is up and running.

Question: In this particular receiver, the 6BY6 pentagrid converter has been replaced by a 6BE6, most likely due to limited (compared to a 6BE6) availability of the 6BY6. Both tubes appear to have the same approximate interelectrode capacitances, and similar operating characteristics. Anyone have a feel for why Hallicrafters chose the 6BY6 instead?

And happy new years to all!

Howie WB2AWQ