Ok. Let’s try this again…RCA 9TC240 Alignment

[Chris K]

VIF? Video if?

[Penthode]

You have to be careful here. there are many hidden things that may be going on here. Increasing the gain of the IF amplifier to max with the pot may induce the IF amplifier to oscillate. I would reduce the gain and increase the RF generator to +10 or +20 if necessary to force a signal through.

What you must confirm is that when you see a deflection on the meter, always confirm you cange vary the level properly eg a smal increase in input yields an increase in the output and vice versa. If you overload an amplifier, sometimes you will find the change of input yield no output change. Or increasing the input may reduce the output. Always make sure increasing the input will increase the output.

You have to understand and get a feel what the circuit is doing. Instead of the VTVM, you could use an oscilloscope on pin 1 of the 12AU7 to see the 1kHz sine wave amplitude. I sometimes like to check things visually to confirm there is actually a sine wave there and I am not just measuring noise. Additionally if the amplifier is overloading, you will see the sine wave clipped. And if the amplifier is oscillating, you will see that too.

[Penthode]

I think you need to go to +10 on the HP 8601a.

[Chris K]

+10dBm got it. I like the idea of using the scope as an addition to the analysis and I will attempt to employ your suggestions. I appreciate all of the time you have generously provided. I might end up not being able to get this working right but I’ve learned a lot about IF signals as well as design and what engineers in the late 1940s were thinking and trying to achieve.

[Penthode]

We have gone so far. I would like to see you finish this and make it work! 😄

[Chris K]

Me too

[Kevin Kuehn]

Considering the level of commitment, so far, along with your spare parts chassis, there's no reason to expect anything other than complete success. Slowly and methodically it will happen.