[morzh]

The bands, as it happened, were not silent, just needed a short piece of wire for an antenna.
The police band is silent but there is a reaction to the antenna, so I think the hardware is fine. Just nothing to listen to.

The hum is persisting. It fully disappears when I ground the chassis.
It is picked up from the detector output but I cannot blame any particular part: it simply is a high input resistance of the first audio stage, so if you leave any wire hanging or move your hand near that connection (the detector out and a bunch of resistors) or the wire, then the hum intensifies.
I put the 1st audio input (well, the long wire from the vol reg wiper) in a shield and grounded it, the hum barely subsided.
I wrapped the 0.01uF cap that goes to the upper pin of the vol reg in the foil and grounded it, it reduced the hum a bit.
I moved the AC power wire away from the connection, it did not help. I even unsoldered it from the power switch and removed it altogether, same result.
The hum is heard when there is no reception and the volume is sufficiently high. Still would like for it to go away.

So, a couple of questions:

1. Those of you who have this version of 16, 121/122 with the 2M volume pot (not the 330K one) or who have done the modification according to the instructions: do you have any hum like this or not?

2. The dial seems to have 5 bands. The sch shows 5-pos switch. But the switch only seems to have 4 positions. Or am I missing something? Probably I am....but I could only switch 3 times.