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

[Chris K]

Originally Posted by Penthode

I mean can you see the needle deflect if you set the generator to another frequency? Is the signal from the generator getting through at all?

Yes it does deflect

[Penthode]

Originally Posted by Chris K

Yes it does deflect

Does the deflection change when you rotate the RF level? If the level changes at 23MHz but not at 21.25MHz, it means the bias is too high and you will have to rotate the bias control to increase the VIF gain.

So now I interpret there is a level at 23MHz and the level goes up if you increase the 8601a output level.

[Penthode]

Look at my CT-100 IF response. See how low the 41.25MHz level is with the trap set to suck away the energy at that frequency. If you adjust the generator to say 42MHz at the peak of the curve, the gain is much higher and a lower RF level is required to easily see that frequency.

At 41.25MHz there is hardly any gain. So you will have to increase the RF level AND increase the gain of the VIF stages.

[Chris K]

Originally Posted by Penthode

Does the deflection change when you rotate the RF level? If the level changes at 23MHz but not at 21.25MHz, it means the bias is too high and you will have to rotate the bias control to increase the VIF gain.

So now I interpret there is a level at 23MHz and the level goes up if you increase the 8601a output level.

OK let me check. By the bias control you mean the 250K pot I have installed correct?

[Chris K]

So here is the baseline setup:









When I change the frequency to 23.0 MHz or to 24, the needle deflects slightly above and below where it is in the baseline setup. When I turn up the gain using the detent steps on the output level, the needle deflects off scale but then returns to the original position and it doesn't matter if I go up or down in gain. Maybe the input at V2 is a problem. I'll check it and the tube. The DMM is the bias but the 250k pot is turned up to max.