The more I study the more I learn. The more I learn the more questions I have.
Here is a close-up of the relevant section.
For reference the note on the schematic and voltage reference chart page says
The stage gain measured values listed above are approximate values for an average operative stage, rather than an absolute value. It should be borne in mind that it is possible to introduce so many variables into the measuring operation, such as, type of equipment used for measuring, handling and placement of probes, the accuracy of allignment, etc., that an absolute reading is impractical. AVC is made inoperative and 3-volt battery bias substituted for measurement.
Sorry for the long quote but I thought it important that you see exactly the verbiage.
Now for my observations.
The rf amp (and also the if amp not shown) appears to be cathode biased with the grid's ground reference coming through the AVC resistors and volume control pot (see schematic in previous post). In this case it would seem that disconnecting the AVC resistor for the rf stage from the 1st audio stage and grounding it should provide proper bias without the use of a battery. It would seem pointless to connect a battery between the grid and ground as the current through the cathode resistor would increase the bias beyond that provided by the battery alone. Thoughts?
The only other AVC connection is to the "bottom" of the secondary side of the tank circuit for the oscillator stage which then feeds what I will call the second control grid since I don't know the correct terminology (pin 6) through the selector switch. The first control grid (pin 4) is grounded through a 20K resistor while the cathode is essentially grounded through the chokes at the bottom of the schematic (voltage chart confirms 0Vdc at the cathode) thus it appears that this tube is biased via. grid leak through the 20K resistor and that the AVC controls gain via the second control grid. So are they asking that the AVC connection to this stage be replaced by a 3V battery (to pin 6)? Minus 3V or plus 3V?
Sorry that I am so muddled up here but this is my first venture into rf. Any guidance would be greatly appreciated.
On a slightly different topic I would assume that replacement or at least verification of cathode resistors and grid leak resistors would be a good idea yes?
mike
P.S. I feel slightly cheated by the lack of a magic eye on my unit so I will probably try to add that after I get her up to snuff.