Quote:
Originally Posted by Penthode
Don't try to listen to the tone. It is AM. The sound discriminator is for FM.
Is the VTVM set to AC? Is the bias pot set correctly? Is the video IF, video detector and video amplifier working properly? Is the VTVM attached properly? You need to systematically go through things.
When setting up to adjust the traps, slightly mis tune the generator. Look for a deflection on the VTVM that goes up and down when the generator output level is adjust up and down. And the deflection must increase as you increase the RF level. I suspect you are going to have to increase the RF level to see a deflection. Again do not adjust things until you see the needle deflect with signal.
Also make sure you are not overloading. Overloading is as bad as no signal: it will distort your results.
Once you see the needle deflecting with signal, then fine tune to the trap frequency. Adjust the RF level until you see just enough to adjust the trap for a dip.
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Ok I will forget about the tone. I’ll answer your questions one by one…The VTVM is set to AC and the range is set to 5V as you said.
The 250K pot is in place and the voltage at R135/136 was adjusted to -4.5V DC
When I have fed a video signal through the antenna from my pattern generator I get an image. The multiburst pattern is ok but the high resolution bands are not sharp. Anyway I’m assuming this means the video IF circuit is working?
The AC probe of the VTVM is connected to pin 1 of V106. The needle on the VTVM does deflect sharply to being pegged if I raise the frequency on the 8601. I get lost with what you say after that. Should I slightly mistune the generator and then do something after that? I got confused because you started talking about signal gain and levels and not changes based on mistuning.