[MrFixr55]

Hi Roy,

One thing about seeing the screen values being closer to published specs with a strong signal. Per the voltage diagram, the measurements are made with the dial around 1000KHz but not receiving a signal and with the antenna disconnected. This will cause no negative AVC voltage, and higher currents (although this is not supposed to happen with a class A amp which at least the IF amp is.

One other possible test would be to measure cathode current. Per both the diagram and the RCA Receiving Tube Manual, the 6A8 cathode current should be 12.3 mA per the schematic, 10.8 per the RCA Receiving Tue Manual (Ver RC14 ca 1940).

For the 6K7 IF stage, the cathode current should be 9.8 mA per the schematic. There is no spec for cathode for the 6K7 in the RCA Receiving Tube Manual (Ver RC14 ca 1940). To measure these currents, the connection between cathode and ground must be broken. This can be done by applying a very thin layer of mylar tape to pin 8 and measuring between the tip of cathode pin (8) and the chassis or socket connection, one tube at a time. this will negate the need of cutting the wire between pin 8 and the chassis.

Remember, that The AVC diode does receive bias from the voltage divider. Verify the correct order and value of those resistors.

You asked about C15. It should be in circuit. Because the screen voltage should be pure DC, there should not be much current drawn by the cap once it charges. Of course, if it us leaky, this could be an issue. Removing C`15 will nit greatly affect Screen voltage and could cause the radio to oscillate, motorboat or use bad language.

There is no statement for cathode, screen or plate current differences based on grid bias. Currents are based on specified grid bias; 0V for both tubes. However, there are statements on transconductance based on grid bias. Normal grid bias for both tubes is 0V. Normal transconductance is listed for normal bias. There is a minimum transconductance listed for negative bias developed by AVC. If I did not post pages from the RCA Receiving Tibe Manual in previous posts to this thread, or if anyone wants them posted again, please let me know. I will be happy to do so.