The PHILCO Phorum
Tuning Eye Help - Printable Version

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RE: Tuning Eye Help - BrendaAnnD - 03-11-2014

That's the AGC action. Without an antenna, the AGC isn't in play, since all stations are weak. The radio runs in its 'full open' mode, to allow in the most signal. So, you don't see much, if any, action from the eye tube. Once you connect an antenna, the AGC starts working because of the stronger signal input. As it 'turns on', the AGC goes more negative and applies a DC voltage to the grids of one or more tubes, making them less sensitive to incoming signals. This negative DC voltage then causes your eye tube to begin to close.

RE: Tuning Eye Help - Jamie - 03-13-2014

Thanks Brenda!.. It's always good to learn new things about radios. I ended up disconnecting R22 and now the eye tube works exactly as needed. The set is almost finished now and I am very happy with it.

RE: Tuning Eye Help - Dan Walker - 04-01-2014

I have had the same type of problems with the tuning eye on
various radios and if is a bright green and does not move , I wait until I align the radio and then if it still does not close properly, I start with the troubleshooting.
Glad you got it going..

RE: Tuning Eye Help - Conelrad - 04-02-2014

Another thing to remember is the lower case "m" was also used to designate kilohms, just like the lower case "w" was used to designate Ohms.

That has fouled up many a schematic reader...

73DG

RE: Tuning Eye Help - Jamie - 04-02-2014

Thanks for that info. It doesn't take much to foul me up..

RE: Tuning Eye Help - Randy H. - 06-16-2014

One more possibility... Unless it's too late. Inside the tube socket cover there is usually a resistor. They OPEN UP, and the tuning eye just sits there. I don't remember the pin numbers, but it's there. It cost less than running another wire up from the chassis. I seem to remeber that the resistor sent amplified AGC voltage to the deflection plate in the tube.