[morzh]

Silvertone was not making any tube radios in 2014. I know that for a fact.
Maybe in 1995...the latest.


The resistors according to the sch is a 2.2K for R3 between the RF xfmr and the ctl grid, and 22K between the 1st grid and the K.

Now, as for the 2.2K resistor.
While not show in the app schematics (like the Radiomuseum reference design), the 2.2K resistor is useful for mostly this reason:

12SA7 is a different type of pentagrid.
It has the Grid 2 connected to SG and uses those as the osc plate.
There is a strong coupling between these and the Control grid, which they envelope.
So, the tube is not very stable around its own frequency and might oscillate around it with that second unintended oscillator, so the two might fight each other.
There are other things too due to very high gain at high frequencies (newer better tube), and since the Plate resistance is so high (1M) and the CG input impedance is super-high, a 2.2K resistor will not attenuate the intended signal much while, by forming a small low-pass with the CG capacitance it will attenuate unneeded VHF and will prevent the oscillations due to that 1st grid and SG enveloping the CG.