B & K Model 1076 TV Analyst "Noise" issues in Video Signal

[vortalexfan]

Hello everyone, late last year one of the members here (I believe it was Kevin K. if I remember right) gifted me one of his B & K TV Analysts and it has come in quite handy in getting some of my old TVs going, but one thing I've noticed and I'm not sure if its part of the normal operations of the unit or if its something out of whack in it, but when I have the unit setup so that I can readjust the video and audio IF stages on a TV that I'm working on (which yes I realize you guys have said not to mess with those adjustments, but those adjustments were already tweaked with previously by someone before I got the TVs) there is some "noise" in the picture when the 400 hz test tone is turned on on the unit, or if its turned to "audio" mode.

Is it normal for there to be distortion on the TV screen when the TV Analyst has an audio signal being injected into the tuner or IF stage of the TV
along with the video signal or is there something wrong with the unit?

I'm asking because when the audio section/test tone portion of the TV Analyst is turned off the video signal is crystal clear (no "noise" in the video).

If this is normal operations and there is something I'm missing in how to operate this unit then I guess I need to go back and re-read the manual.
But it seems like you should be able to have both video and audio going at the same time (since that's the case in TVs and how they work.)

Any help in this matter would be appreciated.

[kf4rca]

From my CATV days, the sound carrier level should be 12 dB lower than the picture carrier level. The picture bandpass should roll off at 4.2 MHz. for a sound carrier at 4.5 MHz.
So, it all depends on the absolute levels of the signals involved.
On the transmitter end, the aural transmitter ERP should not exceed 22% of the visual carrier ERP.