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Old 10-18-2024, 10:47 AM
Chris K Chris K is offline
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Join Date: Jun 2022
Posts: 1,505
Quote:
Originally Posted by Penthode View Post
The resistors temporarily shunting the coils will essentially make the IF amplifier downstream a broadband untuned amplifier. This will allow you to see only the tuner to first IF over-coupled link frequency response without interference. You want to be able to establish a correct response between tuner and first IF before adjusting the remaining stages. So the order of work is:

1. Confirm traps are correct
2. Sweep align the tuner to first IF over-coupled link with resistors shunting the downstream stages
3. Sweep align the entire video IF with the resistor shunts removed.

You should be cognizant of the fact that unless someone has in the past meddled with the tuner-1st IF link transformers, the adjustment should be close. Be aware that if any of the resistors are not connected or loose, it will distort the response you are trying to obtain.

Once the resistors are removed which will raise the gain of the IF amplifier, there is the danger of oscillation which they describe how to handle in the notes. The oscillation will occur if two of the stages are tuned close to the same frequency. The Video IF stages must be properly stagger tuned to be stable.

Here is a Wiki page describing stagger tuning.

https://en.wikipedia.org/wiki/Stagge...reduced%20gain.
Thank you. I have not messed with T-1 and T-101 so hopefully they are close. Still not clear on where to clamp the resistors...for example, on T-102, I am putting the resistor between tabs A and B correct? I'm not shunting the trap coil correct?
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