According to p. 1268 of the
Radiotron Designer's Handbook by F. Langford-Smith (Wireless Press, 1953), the regulatory limit for the current through the RC network in such an AC-DC receiver was 5 mA (the Australian specification from 1937). I couldn't find the UL spec quickly for the US, but I believe it was basically the same. Not normally lethal, but palpable. With 117 V, 60 Hz, the 5 mA limit corresponds to 0.11 uF. The examples below with 0.1 uF in parallel with 220k
![Ohms \$\Omega\$](https://www.eevblog.com/forum/Smileys/default/omega.gif)
would give a total current magnitude of 4.95 mA at 117 V, 60 Hz, dominated by the capacitor.
A later version of the same circuit, found in the 1965 edition (RC-24) of the
RCA Receiving Tube Manual did not have the leakage current specification, but uses 0.1 uF in parallel with 220 k
![Ohms \$\Omega\$](https://www.eevblog.com/forum/Smileys/default/omega.gif)
in that location. The circuit on page 522 replaced the octal tubes of the older circuit with glass-miniature tubes (12BE6, 12BA6, etc.). A more complicated AM-FM circuit on pp 524-5 employed a silicon rectifier. The power-line and switch connections used the same RC network, and included a special line cord with an internal third wire for the antenna.
The connection of the power switch to circuit ground = B- may look counter-intuitive to the IEC generation, but was done since the power switch is immediately behind the audio volume control (full CCW = OFF), and that connection reduced the 60 Hz hum from the power line.
Note that AA5 sets are "AC-DC", due to half-wave rectifier and lack of power transformer. Going into the second half of the 20th Century, there were still DC urban power distribution (at least in New York and Boston) for household loads. Con Ed in NYC finally eliminated the last DC distribution in Manhattan in 2007.